Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session V01: Poster Session III (4:00pm-6:00pm, PT)Poster
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Room: Exhibit Hall C |
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V01.00001: QUANTUM INFORMATION SCIENCE
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V01.00002: Dipolar Chiral Spin Liquids on stretched Kagome lattices Sabrina Chern, Francisco Machado, Michael P Zalatel, Norman Y Yao Modern AMO platforms enable us to directly prepare and investigate a new regime of complex quantum states, notably topological spin liquids. Usually arising as the ground states of highly frustrated systems, spin liquids offer an important landscape for studying how long-range entanglement leads to exotic emergent properties such as topologically protected degeneracy and fractionalized excitations. Recently, important landmark experiments studied the Z2 topological spin liquid; however, preparing other spin liquid phases remains challenging due to the difficulty of stabilizing these complex states. In this poster, we discuss how the combination of fine-tuned geometric control and long-range interactions in AMO systems can naturally stabilize a new type of spin liquid– the chiral spin liquid (CSL). Using large-scale tensor network calculations, we map out the phase diagram of dipolar interacting spins on a stretched (i.e. breathing) Kagome lattice. For intermediate breathings, spontaneous time-reversal symmetry breaking and chiral edge modes establish the presence of a robust CSL ground state. We complement our numerical study by developing a perturbative analysis starting from the large-breathing limit. The resulting effective model captures the qualitative features of the entire phase diagram and provides additional insights into the nature of the competing phases. We conclude by discussing paths to generating and probing the CSL state in the context of Rydberg atom and ultracold molecule tweezer array platforms. |
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V01.00003: Neutral Rydberg atom experiments at Los Alamos National Laboratory Leonardo de Melo, Eric J Meier, Hari P Lamsal, thomas M bersano, Andrew K Harter, Michael J Martin We present recent work on experiments for simulation of quantum magnetism, and enhanced sensing using entanglement via Rydberg interactions. The experiments are based on Rb-87 atoms, with the goal of enabling new capabilities through laser-dressing and creating highly entangled states. |
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V01.00004: Quasi-Floquet engineering of a dipolar many-body spin system in diamond Guanghui He, Bingtian Ye, Ruotian Gong, Zhongyuan Liu, Kater Murch, Norman Y Yao, Chong Zu Floquet (periodic) driving has recently emerged as a powerful technique for engineering quantum systems and realizing non-equilibrium phases of matter. Even richer phenomena can arise in "quasi-Floquet" settings, where a single time-translation symmetry is replaced by multiple time-translation symmetries. Here, we present our recent results on the observation of quasi-Floquet prethermalization in a strongly-interacting nitrogen-vacancy (NV) spin ensemble in diamond. In contrast to a single-frequency (Floquet) drive, we find that the existence of prethermalization is extremely sensitive to the smoothness of the applied field. Moreover, using quasi-Floquet engineering, we realize discrete time quasi-crystalline order which is fundamentally distinct from those realizable in periodically driven (Floquet) systems. Our results open the door to stabilizing and characterizing many-body phenomena in quasi-periodically driven systems. |
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V01.00005: Optimization with Programmable Cavity-Mediated Interactions Jonathan R Jeffrey, Avikar Periwal, Eric S Cooper, Philipp Kunkel, Monika H Schleier-Smith A broad range of optimization problems can be reduced to finding the ground state of interacting spin models. The ability to configure arbitrary couplings between constituent spins is critical for studying different problem instances in the same system. Our previous work [1] demonstrated cavity-mediated programmable interactions between atomic ensembles to engineer tunable couplings for the XY Hamiltonian. In this poster, we present potential schemes for finding approximate ground states of the classical XY Hamiltonian on our cavity platform, where the quantum quench dynamics of the cavity-mediated interactions amplify states that minimize the XY interaction energy. Additionally, we explore adiabatic approaches and generalize to the variational optimization of sequences that prepare low-temperature states for the XY model. We discuss how these approaches scale with system size and interaction graph complexity. Programmable interactions combined with local addressability provide new tools to study the role that complex structures of entanglement could play in efficiently approximating solutions to hard problems. |
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V01.00006: Geometrically frustrated Rb atom arrays in Rydberg states for quantum many-body simulation Fan Jia, Weikun Tian, Wen Jun Wee, An Qu, Prithvi Raj Datla, Jiacheng You, Huanqian Loh Spin-frustrated lattices is an interesting class of condensed matter systems to study, where exotic quantum phenomena such as the quantum spin liquid phase and spin glasses have been predicted to exist. With the recent development of programmable optical tweezer arrays, neutral atom arrays with long-range Rydberg interactions have become a powerful platform to simulate the quantum many-body physics in these systems. Here we introduce our quantum simulation platform using defect-free atom arrays with up to 225 Rb atoms rearranged into triangle-based frustrated geometries. We also report our progress on high-fidelity ground state preparation via optical pumping and Rydberg state excitation through two-photon transitions. The combination of large-scale atom arrays and high-fidelity Rydberg state preparation and detection paves the way for probing quantum many-body physics in large physical systems with frustrated geometries. |
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V01.00007: Robust qudit hamiltonian engineering with spherical 2(d-1)-designs Nathaniel T Leitao, Haoyang Gao, Leigh S Martin, Hengyun Zhou, Iris Cong, Mikhail D Lukin Reshaping a native interaction into a desired form via pulsed coherent control, so-called Hamiltonian engineering, is a ubiquitous technique in quantum science. In this work, we provide a group-theoretic classification for conditions a pulse-sequence must satisfy in order to transform a native qudit interaction into a one with a desired continuous symmetry, which can be one of the many continuous subgroups of $SU(d)$. We find that spherical $2(d-1)$-designs associated to suitably generalized Bloch spheres can be used to construct universal and experimentally robust pulse sequences required to engineer these symmetries. Our approach offers an efficient method for quantum simulation with global control, opening the door to near-term applications ranging from high-spin entanglement enhanced sensing to quantum simulation of non-abelian lattice gauge theories. |
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V01.00008: Simulating quantum Ising dynamics on Rydberg atom chain Xinhui Liang, Zongpei Yue, Yuxin Chao, Chenyuan Li, Meng Khoon Tey, Li You Neutral atom array trapped in programmable optical tweezers with tunable interactions emerges as a promising quantum simulation platform for various quantum phenomenon, such as quantum phase transition, Kibble-Zurek mechanism, quantum spin liquid, and quantum many-body scars, etc. We investigate the low energy excitation and the dynamics in one-dimensional Rydberg atom chain with tuned Hamiltonians. In the region near or away from the critical point, interesting properties of emergent quasiparticle can be benchmarked with analytical and numerical simulations. Our research shows potential advantage in simulating many body dynamics with neutral atom simulator. |
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V01.00009: Quantum metrology and simulation: squeezed matterwave interferometer and cavity-mediated momentum exchange interaction Chengyi Luo, Vanessa P Koh, Graham P Greve, Baochen Wu, Haoqing Zhang, John D Wilson, Anjun Chu, Murray J Holland, Ana Maria Rey, James K Thompson Collective cavity-QED systems have been powerful tools for generating large amounts entanglement involving the internal degrees of freedom of laser-cooled atomic ensembles. By coupling the internal states to the external degrees of freedom, we utimize the cavity-mediated interactions via internal states to generate entanglement between atoms of their momentum states. We then sucessfully inject the squeezed state into a matter-wave interferometer, and for the first time, achive a directly observed phase resolution below the standard quantum limit. By decoupling the internal state from the external states, the interaction between the matter-wave and the high finesse cavity can also induce a momentum exchange interaction where the atoms exchange their momentum states without involving the internal degrees of freedom. With the momentum exchange interaction, we obseve both the well-known one-axis twisting dynamics and the many-body energy gap that protect the coherence of the system. Through enginnering the interaction between matter-wave and cavity, our works could potentially find application in improving quantum sensing with matter-wave as well as providing a new platform for quantum simulation. |
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V01.00010: Quantum Simulation of 1D Lattices with Superconducting Circuits Kellen O'Brien The field of circuit QED has emerged as a rich platform for both quantum computation and quantum simulation. Lattices of coplanar waveguide (CPW) resonators realize artificial photonic materials in the tight-binding limit [1] capable of realizing non-Euclidean geometries [2] and unconventional unit cells [3]. Combined with strong qubit-photon interactions, these systems can be used to study dynamical phase transitions, many-body phenomena, and spin models in driven-dissipative systems. Here we present preliminary measurements from circuit QED lattice systems, including a quasi 1D lattice with gapped flat bands and linear band crossings coupled to transmon qubits. Probing these systems allows us to study photon mediated qubit-qubit interactions as a model for interacting spins in a material defined by the same band structure. |
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V01.00011: Maximizing entanglement entropy and minimizing thermal entropy with an optical tweezer array Adam L Shaw, Pascal Scholl, Ran Finkelstein, Joonhee Choi, Zhuo Chen, Daniel Mark, Richard Tsai, Soonwon Choi, Manuel Endres Here we discuss two new paradigms of studying quantum simulation with atom arrays. In the first, we use an array with as many as 60 Rydberg atoms to quantitatively compare the ability for classical and quantum devices to reproduce some idealized quantum dynamics. We find the cost of the classical simulation increases by orders-of-magnitude with incremental experimental improvements, and show the quantum experiment can outperform the classical computer in finite sampling from maximum entanglement entropy states. Next, we discuss a new approach to quantum simulation with optical tweezer arrays by exerting control over the motional pure state. We show results in cooling to the absolute ground state via a novel form of measurement based cooling, and work towards generating Bell states between the low-lying motional levels of atoms in adjacent optical tweezers. We discuss the potential for full control of the motional degree of freedom for atoms trapped in optical tweezers, including efforts to generate the states necessary for bosonic quantum error correction. |
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V01.00012: Towards Analog Quantum Simulation of Three-Body Hamiltonians with Ytterbium Trapped Ions Visal So, Abhishek Menon, Midhuna Duraisamy Suganthi, Roman Zhuravel, April Sheffield, Mingjian Zhu, Guido Pagano Trapped ion qubits provide a reliable platform for the analog simulation of quantum spin systems because of their high controllability, scalability, and long coherence times. The mapping of quantum field theories to spin models further enables us to study condensed matter, nuclear, and high energy physics with trapped ions. We will report our experimental progress towards an analog quantum simulator with a trapped Ytterbium ion chain, including the characterization of our trap performance and its stability. Here, we also propose the generalized Molmer-Sorensen scheme using higher order spin-phonon couplings to generate an effective three-body Hamiltonian with trapped ions, which would allow us to simulate the U(1) quantum link model. Furthermore, we will present our individual addressing setup using an arbitrary wave generator and a free-spaced acoustic optical-modulator for local optical pumping. This configuration will be used for spin state initialization, which is necessary to characterize the dynamics of the three-body Hamiltonian. |
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V01.00013: Cavity QED as a Platform for Simulating Dynamical Phases of Quenched Superconductors Eric Song, Dylan J Young, Anjun Chu, Diego E Barberena, David Wellnitz, Zhijing Niu, Vera M Schäfer, Ana Maria Rey, James K Thompson While equilibrium properties of physical systems are well described by statistical mechanics, out-of-equilibrium interacting systems exhibit rich phenomenology that is hard to capture with tools from equilibrium settings. Bardeen–Cooper–Schrieffer (BCS) theory is a tremendously successful theory in describing Type I superconductors, accurately modeling various superconductor properties, like the gap and critical temperature. However, experimental verification of long predicted dynamical phases for quenched superconductors remains elusive [1]. In this work, we experimentally demonstrate all three dynamical phases predicted for a quenched BCS superconductor using a strontium (88-Sr) cavity-QED system. We explore the dynamics of the superconducting gap by engineering the dispersion relation and the strength of interaction in the BCS Hamiltonian. We demonstrate how these dynamical phases are universal in different implementations of the Hamiltonian. We also show how this physics can be thought of as a form of gap protection for coherence for applications in quantum sensing and metrology. |
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V01.00014: Toward quantum simulation and networking using the quantum matter synthesizer Lauren S Weiss, Jonathan Trisnadi, Mingjiamei Zhang, Evan P Yamaguchi, Callum L Welsh, Chang Li, Hannes Bernien, Cheng Chin We describe a new quantum simulation and networking platform called the quantum matter synthesizer (QMS), which combines a stable optical lattice with a dynamically controlled tweezer array to prepare and configure individual neutral atoms in the Hubbard regime. In this update we discuss the QMS's cooling and site-resolved imaging, deterministic preparation of atom array, and our scheme to operate the QMS as a quantum network node that distributes entanglement via photons. |
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V01.00015: Realizing Site-Selective Spin-Spin Interactions via Multicolor Rydberg Dressing Xiaoling Wu, Fan Yang, Shuo Yang, Klaus Molmer, Thomas Pohl, Meng Khoon Tey, Li You Arrays of highly excited Rydberg atoms has emerged as a powerful quantum simulation platform. To date, it is still challenging to realize an individually programable spin-spin interaction, which is highly desirable for quantum simulation. Recently, we introduce an approach that makes it possible to implement fully controllable effective spin interactions. We show that Rydberg-dressing with multicolor laser fields opens up distinct interaction channels that enable complete site selective control of the induced interactions and favorable scaling with respect to decoherence. We apply this method to synthesize gauge fields for Rydberg excitations, where the effective magnetic fluxes can be tuned to an arbitrary pattern. |
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V01.00016: A phonon laser in the quantum regime Tanja Behrle, Thanh Long Nguyen, Florentin Reiter, David Baur, Brennan de Neeve, Martin Stadler, Matteo Marinelli, Francesco Lancellotti, Susanne F Yelin, Jonathan Home We demonstrate a trapped-ion system with two competing dissipation channels, implemented independently on two ion species co-trapped in a Paul trap. By controlling coherent spin-oscillator couplings and optical pumping rates we explore the phase diagram of this system, which exhibits a regime analogous to that of a (phonon) laser but operates close to the quantum ground state with an average phonon number of below ten. We demonstrate phase locking of the oscillator to an additional resonant drive, and also observe the phase diffusion of the resulting state under dissipation by reconstructing the quantum state from a measurement of the characteristic function. |
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V01.00017: Two-Photon Routing in Many-Emitter Chiral Waveguide Quantum Electrodynamics Tiberius Berndsen, Imran Mirza In this poster, we present a routing scheme to direct the transport of two photons in a multi-emitter chiral waveguide quantum electrodynamics ladder. At the level of single photons, this problem has been studied both for a single three-level atom case and for multiple two-level atoms (see for example, Phys. Rev. Research 2 (4), 043048, 2020; and Phys. Rev. A 94, 063817, 2016) and it is known that the routing probability drastically reduces in the presence of dissipation effects (such as spontaneous emission from the atoms). In this study, we utilize the interplay between the chiral photon emissions and the collective effects originating from the presence of a one-dimensional chain of two-level atoms to combat the environmental losses to sustain considerably large routing probabilities. Furthermore, with the presence of two photons, we also investigate how the phenomena of bunching and antibunching can help us in the routing process. Since realistic quantum networks must be able to handle vast amounts of information. Therefore studying the problem of two photons and which parameters can be controlled to increase the likelihood of routing is important in developing more reliable long-distance quantum communication protocols. |
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V01.00018: Optimal trajectory unraveling for classical simulation of noisy quantum dynamics Zhuo Chen, Yimu Bao, Soonwon Choi Simulating noisy many-body quantum dynamics in realistic quantum devices using trajectory unraveling is limited by the growth of quantum entanglement. In generic systems, it is previously shown that entanglement in the steady state of trajectories undergoes a phase transition from a volume- to an area-law scaling when increasing the noise rate, allowing for efficient classical simulation only above the critical noise rate. In this work, we introduce an optimal unraveling basis that minimizes the average entanglement entropy in trajectories, reduces the critical noise rate, and therefore extends the regime for efficient classical simulation. We first demonstrate our method in the numerical simulation of noisy Haar random circuits. We then provide an analytical understanding of the optimal basis by mapping the random circuit to an effective classical spin model. Furthermore, we simulate the trajectories of noisy Hamiltonian dynamics and show that the optimal unraveling basis significantly extended the regime of efficient simulation using matrix product states. |
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V01.00019: The emergence of time under interaction of system and environment Sebastian Gemsheim, Jan-Michael Rost The nature of time has fascinated not only physicist for many centuries, but even today no conclusive answer exists about its origin. Is it fundamental or emergent? |
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V01.00020: Hierarchical equations of motion model for phonon and photon correlations Ben S Humphries, Dale Green, Magnus O Borgh, Garth A Jones The hierarchical equations of motion (HEOM), constructed through Feynman and Vernon path integrals, are used to model the dynamics of quantum systems within a statistical ensemble representing the condensed phase. We show that second-order, two-time correlation functions for phonons and photons emitted from a vibronic molecule in a thermal bath produce signatures relating to exchange with the environment and discuss how these arise from the hierarchical equations of motion. Additionally, we discuss the physical justification for the fundamental steps involved in deriving the HEOM and highlight the profound impact on the system memory effects that changes in the spectral density, or bilinear system-environment coupling, can have. |
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V01.00021: How much time do transmitted photons spend as atomic excitations? Theory and experimental progress Kyle Thompson, Kehui Li, Daniela Angulo Murcillo, Vida-Michelle Nixon, Josiah J Sinclair, Amal V S, Andy Jiao, Howard M Wiseman, Aephraim M Steinberg When a single photon traverses a cloud of 2-level atoms on resonance, how much time does it spend as an atomic excitation, as measured by weakly probing the atoms? It turns out that the answer, on average, is simply the spontaneous lifetime multiplied by the probability of the photon being scattered into a side-mode. A tempting inference from this is that photons that are scattered spend, on average, one atomic lifetime as atomic excitations, and photons that are transmitted through the medium spend no time at all. Our previous experimental work (PRX Quantum 3, 010314) shows that this inference is incorrect, and that transmitted photons can indeed spend time as atomic excitations. However, a complete theoretical treatment of the open-system dynamics for such a system has never, to our knowledge, been carried out. We examine this problem using the weak-value formalism and find that transmitted photons in general spend a non-zero amount of time as atomic excitations, and that this time can even be negative. We also determine the corresponding time for scattered photons, which turns out to be related to the "Wigner time" associated with elastic scattering. Progress towards an experimental test of this theory using cold 85Rb atoms will also be presented. This work provides new insight into the complex and surprising histories of photons travelling through absorptive media. |
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V01.00022: Quantum synchronization in spin systems driven by classical coupling fields Balakrishnan Viswanathan, Shan Zhong, Alberto M Marino, Doerte Blume Classical synchronization plays a key role in many areas in the physical sciences and beyond, including in medicine and the social sciences. Several extensions of synchronization to the quantum domain have been considered in the literature, aiming to identify, among other things, whether the quantum nature of the system enhances or inhibits synchronization. We report our progress on a joint theory-experiment project, which aims to quantify quantum synchronization in a spin system, realized using the hyperfine states of alkali atoms in a magneto-optical trap. Even though spin systems have no direct classical analog, the transition to the classical regime can be studied by increasing the number of spin states, i.e., by working with hyperfine manifolds with larger total spin F. We present a theoretical characterization of the system as well as our experimental design. |
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V01.00023: Progress Towards a Novel Hybrid Rydberg-Atom-Microwave-Cavity Quantum System Joshua D Doucette, Juan C Bohorquez, Maxwell Freeman, Mark Saffman, Ravikumar Chinnarasu, Robert McDermott, Shravan Patel Hybrid quantum systems, composed of Rydberg atoms inside microwave cavities, are promising platforms for quantum information science, with applications in hybrid quantum computing architectures and microwave-to-optical photon transduction. We present progress in the development of a novel hybrid atom-cavity system where single neutral cesium atoms will be placed inside of a bulk microwave cavity, with a resonance at 5-10 GHz. The resonator is built to concentrate the field-mode at large distances from internal surfaces, enabling strong Rydberg-atom-cavity coupling while reducing the effects of uncontrolled surface dc electric fields. The atom cooling and trapping will be performed using a grating MOT chip, and the atom transport into the cavity will be done with an optical conveyor belt. This configuration will reduce the system complexity and improve stability. We also present experimental progress demonstrating a novel, Doppler-insensitive, Rydberg excitation scheme, 6S1/2 → 5D5/2 → 52P3/2, with Rydberg Rabi oscillations produced inside of a 77 K cryostat. |
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V01.00024: Towards a quantum network test-bed over deployed fiber with trapped ions Justin Phillips, Ryan Tollefsen, Bingran You, Elia Perego, Erhan Saglamyurek, Inder Monga, Hartmut Haeffner Quantum networking applications rely on the ability to establish entanglement between distant nodes. Recent experiments have succeeded in establishing photon-mediated entanglement between matter qubits over distances ranging from one to hundreds of meters, using solid-state platforms, cold neutral atoms, and trapped-ion systems. Here, we propose to demonstrate high-fidelity and high-rate remote entanglement between two trapped-ion quantum nodes separated by an absolute distance of roughly one kilometer and connected by a five-kilometer telecom band optical fiber. Our node technology will rely on generating ion-photon entangled pairs via a cavity-mediated Raman process in a near concentric cavity regime with singly ionized calcium ions. We will use a novel surface-trap architecture, to be produced in-house, designed for maximal optical access to the ion and shuttling along the trap axis for multiplexing. The emitted photons will be converted to telecom wavelengths (1550 nm) via a highly efficient quantum frequency conversion process, and subsequently will be transmitted over deployed fibers between Lawrence Berkeley National Laboratory and the campus of University of California, Berkeley. This link will serve as a testbed for protocols which require high-fidelity, high-rate remote entanglement of quantum processors such as quantum teleportation and distributed quantum computing over kilometer-scale distances. |
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V01.00025: Building a hybrid quantum system between a trapped ion and solid state donor qubit via path-erasure measurement-based heralded entanglement Carl Thomas, Alexander Kato, Vasilis Niaouris, Jennifer F Lilieholm, Boris Blinov, Kai-Mei C Fu We present progress on generating remote entanglement between a qubit encoded in the hyperfine ground state of 171Yb+ and another qubit implemented via the spin of a donor bound electron in ZnO. Such a system would allow a hybrid quantum device to leverage long ion coherence time with fast solid state gate times. The schema makes use of the close optical transitions accessible in both qubits to implement photonic transduction of the quantum state. By synchronizing excitation pulses and engineering the frequency and waveform of the emitted photons, measurement-based heralded entanglement can be generated by path erasure of the photon source. Our presentation will focus on recent work towards Yb photon shaping and high efficiency coupling of ion light to a single mode fiber. |
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V01.00026: An apparatus for millimeter-wave-mediated quantum gates between Rydberg atoms Michelle Wu, Tony Zhang, Nolan Peard, Lin Xin, Sam R Cohen, Kevin K Multani, Emilio A Nanni, Amir H Safavi-Naeini, Paul B Welander, Monika H Schleier-Smith Rydberg atom arrays have become a leading platform for quantum computing and simulation. However, the power-law decay of the interaction strength in Rydberg systems poses a limitation to efficient generation of long-range entanglement, as compared to the non-local interactions achievable between trapped ions or cold atoms in optical cavities. We propose to trap Rydberg atoms in a millimeter (mm)-wave Fabry-Perot cavity to enable high-fidelity non-local entangling gates. Coupling a transition between circular Rydberg states to a cavity mode will enable atoms to interact with each other regardless of their locations, by emitting and reabsorbing photons to and from the cavity mode. We are developing a high-finesse superconducting cavity with optical access for atom trapping and single-atom detection in a cryogenic apparatus. This new platform will enable entangling gates between atom pairs separated by mm-scale distances, as well as scalable preparation of many-body entangled states. The platform also offers opportunities in quantum simulation, with the interplay of local dipolar and global cavity-mediated interactions raising prospects for accessing novel strongly correlated states. |
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V01.00027: Progress towards coupling an electron-on-neon quantum memory to a superconducting qubit Kaiwen Zheng, Xinyi Zhao, Kater Murch A single electron charge qubit can be defined by electrostatic gating of an electron trapped in vacuum above the surface of solid neon at millikelvin temperatures. Recent experiments have demonstrated coherent control and dispersive measurement of the charge qubit using a superconducting microwave resonator. We present our recent progress toward a coherent interface between a superconducting transmon qubit and the electron-on-neon charge qubit. We utilize a shared resonator bus to mediate interactions through virtual microwave photons. Our progress is a first step toward the realization of a long-lived quantum memory based on the spin states of the electron that interfaces with the circuit quantum electrodynamics architecture. |
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V01.00028: COLD ATOMS, IONS, MOLECULES, AND PLASMAS
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V01.00029: Low-phase-noise laser system for the STIRAP transfer of Ultracold 6Li40K molecules Victor Andre Avalos Pinillos, Xiaoyu Nie, Canming He, Anbang Yang, Kai Dieckmann Ultracold rovibrational ground state molecules have proved to be a versatile platform to perform quantum stimulation, quantum information, quantum chemistry and metrology. A stablished method to create them consists in performing stimulated Raman adiabatic passage (STIRAP) on Feshbach molecules. To perform STIRAP, we prepared a low phase-noise laser setup capable of maintaining coherence between the two Raman optical beams required, which are commonly referred as stokes and pump. First, we designed long (20cm) external-cavity-diode-lasers for both optical beams, this is known to reduce the achievable stabilized laser linewidth which is associated to the phase noise. Secondly, a dual wavelength optical high-finesse cavity (HFC) was constructed to stablish longer coherence lengths for the Raman lasers when both of them are stabilized to it. When frequency locking the lasers to the HFC, linewidths were measured at 300Hz for pump and 500Hz for stokes. The phase noise measurement was performed on each Raman laser, by using the transmission of the HFC as a noise filtered reference to produce a beatnote with the laser diode beam. The phase noise of the beat was measured using a balanced photodiode in order to reduce the amplitude noise. The HFC linewidth puts a lower limit on the frequency of the measurable phase noise (10kHz for pump and 40kHz for stokes) and the balanced photodiode floor noise puts the upper limit at 10MHz. The result of the phase noise measurement shows an improvement of one order of magnitude on the power ratio of sidebands over carrier frequency. The comparison was made to previously used short (2cm) external-cavity-diode-lasers. We calculated the expected STIRAP efficiency dependant on pulse duration and Rabi frequency of the lasers. With the improvements we could stablish a theoretical workable area where STIRAP efficiency surpassed the 90 percent mark. |
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V01.00030: Rydberg atom three-body recombination rates as a function of electron magnetization in ultracold neutral plasmas Ryan Baker, Bridget O'Mara, Jacob L Roberts Rydberg atom formation via three-body recombination in ultracold neutral plasmas is interesting both from the perspective of studying processes in cold plasmas and because the main limitation on the coldest achievable electron temperatures comes from heating from three-body recombination. Other plasma systems such as those associated with antihydrogen formation are strongly impacted by three-body recombination as well. Recombination rates are predicted to decrease substantially as a function of magnetic field in the plasma. Ultracold neutral plasmas are comparatively easy to magnetize as comparatively low laboratory magnetic fields and so are excellent systems to conduct studies of magnetization effects on Rydberg formation rates. We describe our techniques for measuring these rates experimentally as well as report observations and simulation results relevant to our measurements. |
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V01.00031: Indication of a phase transition in time during the relaxation of an open quantum system Julian Feß, Ling-Na Wu, Artur Widera, André Eckardt, Alexander Schnell, Jens Nettersheim, Sabrina Burgardt, Silvia Hiebel Phase transitions correspond to the singular behavior of physical systems in response to continuous control parameters like temperature or external fields. Near continuous phase transitions, associated with the divergence of a correlation length, universal power-law scaling behavior with critical exponents independent of microscopic system details is found. |
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V01.00032: Few-body systems interacting near the unitarity regime Michael D Higgins, Chris H Greene There have been many studies over the years on few-body systems interacting near the unitarity limit. Notable studies have been extensively researched for systems of bosons, particularly to understand the Efimov effect for three-interacting bosons near s-wave unitarity and its implications for N-boson systems. There have been other interesting systems consisting of interacting fermions like in the BEC-BCS corssover problem and in the study of polaron physics. In our previous work, three and four equal-mass systems in various angular momentum and spin states for different s-wave and p-wave interactions were studied to investigate universal physics when the interactions are tuned near the unitary limit, i.e. when the scattering length or scattering volume approaches infinity [Phys. Rev. A 106, 023304 (2022)]. In this current work, we expand on the previous study using the adiabatic hyperspherical treatment, focusing on N-body systems for N>3 in search of universal physics near the unitarity regime, considering both N=4 and N=5. An interesting system to look at is an impurity embedded in a sea of fermions, which will aid in our understanding of Bose-polaron physics. Furthermore, through a comprehensive analysis of the hyperspherical potential curves for these different systems, information about the long-range dependence can provide insight into various threshold-law behaviors that govern many low-energy processes such as N-body recombination. |
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V01.00033: Light induced atomic desorption of strontium atoms Hari P Lamsal, Eric J Meier, Leonardo de Melo, Thomas M Bersano, Andrew K Harter, Malcolm G Boshier, Michael J Martin Light induced atomic desorption (LIAD) has been proved useful as a source of atoms at relatively low temperature (room temperature) and has been used in various applications, such as magneto-optical trapping and Bose-Einstein condensation in microelectronic chips. We report on our exploration of using LIAD to produce strontium atoms for cold atom experiments. We have tested the following two LIAD methods. First, we coat various substrates including sapphire and borosilicate glass with strontium atoms using atomic dispensers. We then use LIAD to liberate atoms from the coated surface. And second, we put strontium oxide powder inside a glass cell under vacuum and directly focus the laser light into the sample to liberate atoms. We report on the properties of the liberated atoms and comment on the feasibility of LIAD as an atomic source for cold atom experiments. |
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V01.00034: Experiments with the Grating MOTs of Strontium Sara Ahanchi, Peter K Elgee, Ananya Sitaram, Stephen P Eckel, Nikolai N Klimov, Gretchen K Campbell, Daniel S Barker We report realization of a strontium grating magneto-optical trap (MOT) operating on the narrow, 1S0 → 3P1 transition and implementation of sawtooth wave adiabatic passage (SWAP). Grating MOTs, which use a nanofabricated diffraction grating to greatly simplify the MOT optical layout, are a platform that can realize quantum technologies outside the laboratory. Cold-alkaline earth atoms are a central component of many quantum devices, such as clock atom interferometers and optical clocks. The 1S0 → 3P1 transition grating MOT traps as many as 3×106 88Sr atoms and cools them to an average temperature of 3.7 μK. Using SWAP, we can roughly double the transfer efficiency from the first stage of cooling, a 1S0 → 1P1 transition grating MOT, to the 1S0 → 3P1 MOT. Despite being able to capture on the order of 3×106 87Sr atoms in the 1S0 → 1P1 MOT, we have been unable to observe trapping in the 1S0 → 3P1 grating MOT. We present rate equation and optical Bloch equation simulations of the 1S0 → 3P1 grating MOT, which suggest that grating MOTs of 87Sr will be extremely difficult to realize because traditional "stirring" schemes are ineffective. Our results show that chip-scale quantum devices using bosonic strontium are within reach on the grating MOT platform. |
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V01.00035: Measurement of the trap parameters of 133Cs cold atoms in a magneto-optical trap by external periodic perturbation Jaeuk Baek, Min-hwan Lee, Geol Moon We report the trap parameters of 133Cs cold atoms in a magneto-optical trap (MOT). We realized the forced damped harmonic oscillations of 133Cs cold atoms by the periodic intensity modulation of the lasers counter-propagating along anti-Helmholtz coil axis. The trap parameters such as trap frequency, damping coefficient, and driving force were measured by the resonance curve, which is obtained through the vibrational amplitude of 133Cs cold atoms according to modulation frequency of the laser intensity modulation. The experimental results were consistent with our theoretical model, which considers all the possible transition lines used to trap 133Cs atom. |
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V01.00036: Optimizing atom transfer in a double magneto-optical trap system with machine learning Thomas M Bersano, Ceren Uzun, Michael McKerns, Michael J Martin, Malcolm G Boshier A push beam is a common tool for transferring atoms from a vapor chamber magneto-optical trap (MOT) to an ultra-high vacuum MOT (UHV-MOT) in ultracold atomic experiments. Many of these experiments leave the push beam on continuously during UHV-MOT loading, but there is documented evidence that, for a narrow set of parameters, pulsing the push beam during loading results in increased atom capture at the UHV-MOT. Additionally, while the performance of continuous loading is explained by atomic two-level models, pulsing introduces time-dependent behavior which is non-trivial to account for when optimizing loading in the double-MOT system. For these reasons, we choose to improve the performance of our 39K double MOT with a machine learning (ML) algorithm which efficiently scans the full parameter space by using a combination of online optimization and offline modeling of the apparatus response. Future plans include further ML-optimization of cooling steps on the road to quantum degeneracy while optimizing for appropriate figures of merit (e.g. atom number, temperature). |
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V01.00037: Identifying laser cooling schemes for molecules with non-diagonal Franck-Condon Factors Niccolò Bigagli, Anna Dawid, Daniel W Savin, Sebastian Will Due to their rich internal structure and complex interactions, ultracold neutral and ionic molecules offer exciting prospects to advance quantum chemistry, sensing, simulation, and information. In recent years, ultracold neutral molecules have been prepared via assembly from ultracold atoms (e.g., KRb, NaCs) or via direct laser cooling of molecules with highly diagonal Franck-Condon factors (e.g., SrF, CaF, YO). Much less explored are ultracold ionic molecules (e.g., N2+, CaH+, HCO+, N2H+). They are typically cooled via sympathetic cooling with atomic ions, but this approach limits research to experiments that are unaffected by the presence of atomic ions in the trap. |
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V01.00038: Laser-cooled ion crystals in the Fermilab IOTA storage ring: a feasibility study Boris Blinov, Sergei Nagaitsev, Timur V Shaftan, Thomas Olson, Jonathan Jarvis, Andreas Adelmann, Philipp Windischhofer We study the feasibility of storing and laser-cooling millions of ions in the Fermilab IOTA ring to form a 1-dimensional Coulomb crystal as a pathway to a large-scale quantum simulation and computation technology. We are developing the full suite of capabilities and techniques to create and study these crystals, as well as to prepare, manipulate and read out quantum states of the ion qubits. We describe our conceptual design of this system as well as the technology and physics challenges that such a system can address, once completed. We focus on ion cooling simulations, diagnostics and modeling for these conceptual studies. |
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V01.00039: Progress towards a high data rate grating magneto-optical trap Roger Ding, Adrian S Orozco, Peter D Schwindt, Jongmin Lee Light-pulse atom interferometers (LPAIs) are of high importance for advanced inertial sensing applications due to their exquisite sensitivity and potential for long-term stability but moving from a laboratory setting to real-world environments remains difficult. Cold-atom LPAI accelerometers interrogate free-falling atoms with a sensitivity σg∝1/T2 for interrogation time T. Therefore, the best sensitivity is achieved by maximizing T but this also means the LPAI is susceptible to motion occurring on timescales ≤T. One solution is to trade sensitivity for data rate to reduce the detrimental effects of relative motion between the freefalling atoms and the interrogation lasers. Building upon previous work that demonstrated a proof-of-concept grating magneto-optical trap (GMOT) LPAI accelerometer [1], we present work towards achieving high cycle rate (≥100 Hz) GMOT operation with the goal of mitigating detrimental effects of relative motion in a simple and compact package. |
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V01.00040: Progress Towards Laser Cooled Polyatomic Molecules for Beyond-Standard-Model Physics Searches Alexander J Frenett, Zack Lasner, Hiromitsu Sawaoka, Abdullah Nasir, Takashi Sakamoto, Annika Lunstad, Mingda Li, Tasuku Ono, Hana Lampson, John M Doyle Recent work in molecular laser cooling has extended the technique to polyatomic species. Until this point, however, full 3D laser cooling has been limited to light molecules, which have limited use in probes of fundamental physics. In this poster, we report progress towards cooling and trapping SrOH molecules for probes of the electron permanent electric dipole moment and ultralight dark matter. We present high-resolution robvibrational spectroscopy identifying the dominant vibrational leakage channels in the laser cooling process. We also report progress towards transverse cooling a beam of SrOH and full 3D cooling and trapping of the species. Finally, we discuss the planned steps towards creating an ultracold sample suitable for precision measurements. |
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V01.00041: Repetitive nondestructive readout of nuclear spin qubits in a 171Yb atom array Xiye Hu, William Huie, Neville Chen, Lintao Li, Zhubing Jia, Calvin Sun, Jacob Covey Neutral atom arrays have seen increasing attention and development as a platform for quantum |
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V01.00042: Operating a Quantum Gas Research Facility on the ISS James M Kohel, Robert J Thompson, Jason R Williams, David C Aveline, Ethan R Elliott, James M Kellogg, Kelly L Perry, Leo Y Cheng, Walker L Dula, Irena Li, Leah E Phillips, Sarah K Rees, Gregory Y Shin, Oscar Yang, Kamal Oudrhiri, Shahram Javidnia NASA's Cold Atom Laboratory (CAL) is a multi-user quantum gas research facility for the study of ultracold gases in the microgravity environment of the International Space Station. We present an overview of the first five years of operation on orbit, including efforts to optimize remote operations in orbit and how our experiences guide development of follow-on missions. |
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V01.00043: Progress towards harnessing Rydberg-atom synthetic dimensions in arrays of single atoms. Brent F Kruzel, Soumya K Kanungo, F B Dunning, Tom C Killian Rydberg-atom synthetic dimensions1 have potential for exploring new physics by realizing higher-dimensional synthetic lattices, and non-trivial spatial and band-structure topologies. In such systems, tunneling along the synthetic dimension is set by the millimeter-wave (~ 20 GHz) coupling of synthetic lattice sites, i.e., Rydberg levels. By using atoms trapped in closely-spaced optical tweezers with long-range dipolar interactions, it should be possible to realize many-body systems with localized interactions in synthetic space. Here, we present progress towards construction of an experimental apparatus optimized for application of millimeter-waves (10-50 GHz), charged-particle detection methods, and optical tweezers. A finite element analysis of the millimeter-wave propagation is used to guide design and minimize interference patterns and resonances inside the vacuum chamber, which can create challenges for engineering synthetic dimensions with specified tunneling rates.. |
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V01.00044: Investigation of Buffer-Gas cooled AlCl for laser cooling and trapping Li-Ren Liu, Chen Wang, John R Daniel, Madhav Dhital, Boerge Hemmerling Ultracold molecules provide an ideal testbed for fundamental physics. The unique and complex energy structures can enhance the sensitivity for precision measurements and can enable the exploration of new physics, such as searches for the electron electric dipole moment, the control of ultracold chemical reactions, and new quantum information processing platforms. However, the complex transitions of molecules also make them more difficult to be cooled and trapped. Aluminum monochloride (AlCl) has a highly diagonal Frank-Condon factor of 99.88%, making it an excellent candidate for laser cooling. In our experiment, AlCl is generated via laser ablation on KCl:Al target in a cryogenic buffer-gas beam cell. Here, we report on our progress towards slowing a beam of AlCl with custom-build high-power UV laser systems at 261 nm and on survey spectroscopy of other diatomic species, which are potentially interesting for laser cooling. |
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V01.00045: Progress towards pulse sequence engineering for large momentum transfer in hot helium beam Xiaoyang Liu, Harold J Metcalf The strength of optical forces on atoms derives from the rate of exchange of momentum between light and atoms. In previous research, we describe the use of periodic Adiabatic Rapid Passage (ARP) sequences to increase both the excitation and emission rates, and thereby strengthen the optical force to FARP » Frad Ξ hkγ/2. In the recent progress we compared adiabatic sequential pulse with the diabetic sequential pulse designed from floquet atom optics [1] and shortcut to adiabaticity[2] when applied in hot atomic beam source and investigate of the connection between two pulse design methods. |
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V01.00046: Progress on four-wave mixing in mercury for lyman-alpha cooling of hydrogen Tharon D Morrison Precision hydrogen spectroscopy is important for determining the proton size, fundamental constants, and testing matter-antimatter symmetry. Slowing or trapping hydrogen atoms and beams will provide significant reductions in observed linewidths and systematic uncertainties for hydrogen's narrowest transitions. We report on progress of a CW Lyman-alpha system using four-wave mixing in mercury and discuss ways it can be future utilized to laser cool hydrogen by aid of magnetic guides. |
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V01.00047: Improving matter-wave lensing with multiple Gaussian lenses Harshil Neeraj, David C Spierings, Joseph McGowan, Nicholas Mantella, Aephraim M Steinberg Matter-wave lensing, also known as delta-kick cooling (DKC), is a common technique used to prepare narrow momentum distributions by applying an optical "lens" to collimate a cloud of atoms while preserving phase-space density. DKC works by using free expansion to allow the position and momentum of atoms to get correlated before using a linear force from a harmonic potential to cancel that momentum and bring the atoms to a near rest. DKC has been used to achieve record-low temperatures in the pico-Kelvin range, resulting in long coherence lengths. The cooling performance in DKC is limited by the ratio of the final and initial sizes of the cloud and the harmonic nature of the kicking potential. One common implementation of DKC in cold-atom experiments involves using red-detuned Gaussian laser beams to apply an attractive, approximate harmonic potential. Often, the non-harmonic part of the potential limits the final size of the cloud after free expansion, which has to be chosen such that the atoms stay near the potential minima. Recently, it has been shown that using an additional repulsive potential can speed up DKC [Phys. Rev. Research 3, 033261 (2021)]. Here, we present results that show how to improve the cooling performance of delta-kick cooling with Gaussian beams. We show that a combination of Gaussian attractive and repulsive potential kicks can be used to extend the region over which the cloud of atoms sees a linear force, resulting in lower final temperatures. This work also extends the close analogy between DKC and optics, where multiple matter-wave lenses can be used to cancel aberrations, much the same way as aberrations are compensated for with a combination of optical lenses. |
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V01.00048: A Dynamic Locking System for Bose-Einstein Condensation and Four-wave Mixing Experiments Hio Giap Ooi, Sankalp Prajapati, Sam Manley, Sean M Smith, John E Furneaux, Arne Schwettmann A spin-exchange exchange collision in an F=1 spinor Bose-Einstein Condensate (BEC) converts pairs of atoms with magnetic quantum numbers mF = 0 into entangled pairs with mF = +1 and mF = -1. In order to perform a below shot-noise measurement of the spin populations in our sodium spinor BEC, we plan to image the gas using entangled twin-beams of light. The entangled beams are generated via a nonlinear four-wave mixing (FWM) process. To study spin dynamics with such a low noise measurement, it is important to ensure that the lasers used for both the BEC and the FWM are locked to their respective wavelengths appropriately. The laser used for laser cooling and trapping is locked on the sodium D2 line, whereas the FWM process is implemented on the D1 line. Therefore, a dynamic laser locking system for BEC and FWM experiments is necessary. Our locking system will allow the laser to be locked on or in-between the sodium lines, by adjusting the RF driving frequency of an acousto-optic modulator set up in a double-passing configuration within several hundred MHz. In this poster, we present the design and apparatus for our dynamic laser locking system for both the spinor BEC and FWM systems. |
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V01.00049: Low Noise Bipolar Current Source to Precisely Control Magnetic Fields in Ultra-cold Atoms Experiments Sankalp V Prajapati, Hio Giap Ooi, Sam Manley, John E Furneaux, Arne Schwettmann Ultra-cold atom experiments often require a precise control over magnetic fields to provide a quantization axis and split the magnetic sublevels. A stable quadratic Zeeman effect is especially important in our experiments with sodium spinor Bose-Einstein condensates. It provides a sensitive knob that allows us to control entanglement generation via spin-exchange collisions. To better control the linear and quadratic Zeeman effects, we have constructed a low noise bipolar current source for three pairs of Helmholtz coils which create a uniform magnetic field at the center of the vacuum chamber. This analog-controlled current driver circuit can source or sink up to 8 A. This will allow us to tune and stabilize the magnetic field to an arbitrary value, which will result in a more precise control of spin-exchange collisions. In this poster, we provide an insight into the design of this current driver circuit. |
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V01.00050: Point Source Atom Interferometry with Sr-88 Sharika Saraf, Kefeng Jiang This poster will describe our experimental apparatus for point source atom interferometry using Sr-88 atoms. Point source atom interferometry can be used to map information about the wavefront profile of a beam onto a spatial interference pattern in an atomic cloud. It can thus be used to mitigate systematic errors such as wavefront aberrations in precision measurement experiments. Our apparatus starts with an atom source with an inbuilt Zeeman slower and 2D MOT, which directs cooled atoms into a 3D MOT. This MOT uses light at 461 nm and targets the 1S0 - 1P1 transition. Repumper beams at 707 nm and 679 nm reduce leakage. The apparatus also includes a high power, on resonance fluorescence beam and a push beam. The atoms then see counter-propagating interferometry beams at 689 nm. An FPGA-based pulsing system with computer control performs fast and precise timing on the magnetic field, camera exposure, laser beams, and their AOM drivers. The magnetic field can be rapidly shut off with the help of our switching circuit. We will present initial atom interferometry results from this apparatus. |
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V01.00051: Progress towards Programmable Strontium Atom Arrays Ximo Sun, Aaron Holman, Weijun Yuan, Chun-Wei Liu, Kevin Wang, Xiaoyan Huang, Nanfang Yu, Bojeong Seo, Sebastian Will We report on the realization of a programmable atom array created by holographic metasurfaces. We trap bosonic 88-strontium in a variety of geometries using metasurfaces: flat optical devices that are highly integrable and withstand high optical powers. Using a "sorting beam" generated with programmable crossed AODs, we are working towards unity filled arrays in non-periodic patterns. We additionally explore a new magic wavelength of 520 nm for strontium's intercombination line. Leveraging the favorable power handling of metasurface we are exploring the possibility of large-scale high quality arrays with thousands of traps, which is highly desirable for the use of atomic arrays in optical tweezer clocks and for scalable quantum simulation devices. In particular, the setup is geared towards creating highly entangled many-body quantum states that display subradiance. |
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V01.00052: Optical Deceleration and Magnetic Trapping of Atomic Hydrogen William L Tavis, Ryan Bullis, Samuel F Cooper, Scott Johnson, Josh Cisneros, Dylan C Yost Precision spectroscopy of atomic hydrogen allows for the determination of fundamental constants and provides tests of bound-state quantum electrodynamics. The leading sources of uncertainty in hydrogen beam experiments can usually be traced back to velocity-dependent effects. To address these challenges, we will describe a method to load atoms from a cryogenic hydrogen beam into a magnetic trap which is itself at room temperature. This technique will rely on the optical dipole force provided by an accelerating optical lattice. After loading, we aim to perform spectroscopy at velocities roughly an order of magnitude lower than the mean velocity of the atomic beam. |
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V01.00053: Atom-trap trace analysis of 41Ca/Ca down to the 10-17 level Tian Xia, Tong-Yan Xia, Wei-Wei Sun, Sven Ebser, Wei jiang, Guo-Min Yang, Hui-Min Zhu, Yun-Chong Fu, Fang Huang, Guo-Dong Ming, Zheng-Tian Lu The cosmogenic isotope 41Ca with a half-life of 99,000 years can in principle serve as tracer for environmental processes at an age scale beyond the reach of 14C. With accelerator mass spectrometry, the ratio of 41Ca/Ca has been measured down to the 10-15 level in natural samples. A wide range of potential applications, such as burial dating of bones and exposure dating of rocks, require measuring even smaller 41Ca/Ca ratios in the range of 10-16 to 10-15. Here we achieved this by employing the atom trap trace analysis method in which individual 41Ca atoms are selectively captured in a magneto-optical trap and counted by detecting their fluorescence. We realized a precision of 12% on the 41Ca/Ca ratio at the level of 10-16 and achieved a detection limit at the level of 10-17, which is below the distribution of natural abundances. We verified the accuracy of the 41Ca/Ca results through a series of measurements of reference samples, and performed demonstration analyses on bone, rock and seawater samples. Our table-top method has the potential to explore the suitability of 41Ca as tracer. |
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V01.00054: An ultracold indium apparatus Xianquan Yu, Jinchao Mo, Tiangao Lu, Ting You Tan, Travis L Nicholson Despite the remarkable progress made by ultracold physics in the past few decades, most atomic species have not been cooled to quantum degeneracy. Our work is the first to explore an atom (indium) in main-group III of the Periodic Table at ultracold temperatures. |
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V01.00055: Topological band structure engineering of a one-dimensional optical lattice system with resonant shaking Dalmin Bae, Myeonghyeon Kim, Jun Y Park, Jin Hyoun Kang, Yong-il Shin Floquet engineering is a novel way to generate new properties out of a system. We study the topological band structure of a resonantly shaken one-dimensional optical lattice system, where the lattice potential is periodically modulated to couple the two lowest bloch bands. In a two-band approximation, we numerically show that degenerate edge states appear under a certain driving condition and the corresponding topological phase is protected by the chiral symmetry of the periodically driven system. The system's micromotion is characterized with oscillating Zak phases which are quantized only when the chiral symmetry condition is explicitly satisfied. We also describe the topological charge pumping effect, slowly modulating the driving parameters around a critical point, and investigate its adiabaticity with increasing modulation frequency. Finally, we discuss the experimental feasibility of realizing a flat band in the shaken lattice system. |
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V01.00056: Towards Ultracold Fermions in Optical Kagome Lattices Shao-wen Chang, Malte Nils Schwarz, Rowan Duim, Charles D Brown, Ryan Everly, Dan M Stamper-Kurn We report our progress towards incorporating 40K, a fermionic isotope of potassium, into our optical kagome lattice experiment. Due to the highly frustrated nature of the kagome lattice, there is a macroscopic degeneracy in the s-orbital manifold, which results in strong enhancement of interaction effect. This platform is therefore ideal for studying strongly interacting manybody phenomena, such as superfluidity and flat band ferromagnetism. We describe the necessary instrument upgrades on the previous 87Rb machine, as well as several additional capabilities planned for the new experiment. |
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V01.00057: Semiclassical Dynamics of Rydberg Electron in a Ponderomotive Optical Lattice Bineet K Dash, Alisher Duspayev, Georg A Raithel While semiclassical limits of quantum mechanical systems are well-defined in systems with a classically regular counterpart, the quantum behavior of classically chaotic systems remains a topic of investigation. In the past decades, manifestations of chaotic behavior have been demonstrated in model Hamiltonians like dynamical billiards, as well as in physical systems such as the quantum kicked rotor, the diamagnetic hydrogen atom, and Rydberg atoms in strong fields. Here, we numerically investigate the onset of chaos in the semiclassical dynamics of a Rydberg electron subjected to a strong sinusoidal trapping potential implemented via a one-dimensional, GHz-deep ponderomotive optical lattice. In this poster, we will introduce the physical system of interest and present numerical results on classical phase-space dynamics. The system is characterized by electronic energy, z-angular momentum, lattice period and lattice depth. For sufficiently deep lattices, and for appropriate Rydberg states and aspect ratios of atom size to lattice period, the time evolution under the nonlinear optical-lattice potential is found to give rise to ergodicity and exponential divergence of neighboring trajectories. The significance of the results in the corresponding quantum problem will be discussed. |
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V01.00058: Progress toward building a quantum gas microscope for ytterbium atoms at KRISS Jeong Ho Han, Haejun Jung, Yunheung Song, Jae Hoon Lee, Jae-yoon Choi, Jongchul Mun We report on the ongoing development of a quantum gas microscope apparatus for ytterbium atoms at KRISS. To detect individual atoms at a single-site resolution, we adopt the deep potential method, which does not require any cooling mechanism during the imaging process. The evaporatively cooled ytterbium atoms are repeatedly prepared in a single layer of an accordion lattice and adiabatically loaded in a 2D optical lattice. We illuminate the atoms using the laser detuned from the resonance, while the atoms are kept pinned in the lattice. The fluorescence emitted from the atoms is collected through a high NA imaging system, which is designed to have a long working distance. We expect an immediate extension to fermionic ytterbium isotopes and aim to explore rich physics such as SU(N) Fermi-Hubbard model and the Kondo problem in the near future. |
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V01.00059: Realization of One-dimensional Anyons with Arbitrary Statistical Phases Yanfei Li, Joyce Kwan, Perrin C Segura, Sooshin Kim, Brice Bakkali-Hassani, Markus Greiner Anyons are indistinguishable particles whose many-body wavefunction acquires a phase between 0 and π when exchanging their positions. We realize a one-dimensional Anyon-Hubbard model (AHM) with ultracold Rubidium 87 atoms in a tilted optical lattice.To engineer the desired Hamiltonian, we use a novel three-tone lattice amplitude modulation technique that allows us to continuously tune the exchange statistical phase of two particles. This Floquet driving technique effectively realizes a Bose-Hubbard model with an occupation-dependent hopping phase that maps onto the AHM. As a benchmark, signatures of anyonic statistics are observed in interferometric two-particle quantum walks. We prepare two particles sitting on adjacent sites and allow them to expand in a chain under the Floquet Hamiltonian. From density correlation functions, we observe slower density expansion and manifestation of pairing for non-zero statistical phases, even in the absence of on-site interactions. We also demonstrate the ability to vary the on-site interaction strength by detuning the modulation frequencies. For non-zero interaction energy, we observe asymmetric density transport which suggests broken inversion symmetry in the AHM. Our technique paves a way to study fractional statistics and explore statistically induced phase transitions. |
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V01.00060: Origin of directed atomic propagation in driven dissipative optical lattices: Prospects for precisely controlled ratcheting with quasiperiodic driving fields Stone Oliver, Daniel Wingert, Krishna Pandey, Grant Brown, Chanakya Pandya, Samir Bali Atoms confined in a three-dimensional dissipative optical lattice oscillate inside potential wells, and occasionally hop to adjacent wells, thereby diffusing in all directions. Illumination by a weak probe beam modulates the lattice, yielding propagating atomic density waves that travel perpendicular to the direction of travel of the probe. Experimental and theoretical investigations have revealed that if the probe propagates along a lattice symmetry axis, this directed motion of the atoms originates from a resonance between the intrawell atomic oscillation frequency and the modulation frequency. On the other hand, if the probe does not propagate along the symmetry axis, this results in a spatial quasiperiodic driving of the lattice. In this case, the propagating atomic density modes originate from a velocity matching between the atomic density wave and a propagating modulation wave created by the off-axis probe. Further exploration of quasiperiodic driving, for example in the time domain, may yield directed atomic propagation in highly controlled, arbitrary directions. |
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V01.00061: Simulations and theory of power spectral density functions for time dependent and anharmonic Langevin oscillators AbdAlGhaffar Amer, Francis J Robicheaux The power spectral densities (PSDs) of trapped nanoparticles is conventionally compared to those of a simple harmonic Langevin oscillator (SHLO) assuming that the particle is oscillating in the harmonic regime. We show numerically that for a particle in a Paul trap that is oscillating in the stable region of the Mathieu equation, its PSDs can deviate significantly from those of the SHLO. We derive analytic expressions for the PSDs and show that they are in agreement with the numerical PSDs obtained by simulating the motion for a sufficiently long period of time in comparison to the damping time. We also derive analytic expressions for the PSDs of multiple cases of perturbation to a SHLO and show that they agree with the numerically obtained PSDs even when the resulting PSD strongly deviates from that for a SHLO. We consider a linearly drifting or an oscillating frequency that could be a result of experimental configuration. We also consider the case of a particle oscillating in a slightly anharmonic regime. Our results show that a modified version of the PSD which was utilized in cite{Barker} changes less than the conventional PSD under the above mentioned perturbations to the SHLO. |
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V01.00062: Non-commuting dynamics in light-ion-interactions in an ion trap system Oana Bazavan, Sebastian Saner, Donovan Webb, Gabriel Araneda, David M Lucas, Raghavendra Srinivas, Chris J Ballance Laser-driven interactions are ubiquitous in trapped-ion systems for quantum computing or simulation. As the laser power is increased to strengthen the interaction, non-commuting terms that could originally be ignored start having a significant effect on the dynamics. Here we present two methods to mitigate the effect of those terms. |
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V01.00063: Collisional Re-ordering of Ionic Crystals Brant B Bowers, Sara Mouradian, Zengli Ba We advance a computational model for temperature and pressure dependent collisions between background gas and a three-ion linear ionic crystal in a vacuum chamber. We consider ion loss and chain reordering from the perspective of error minimization in quantum computing. This model can be used to extract the required temperature (or pressure) to achieve a given error rate in a linear ion trap with a given set of radial and axial frequencies. For example, a three-ion crystal in a trap with radial frequency 4MHz and axial frequency 0.4MHz at 300K needs to be pumped to a pressure of ~3.2*10^-12 torr in order to maintain an ion order lifetime of 1 hour. Ongoing improvements to this model based on the partial pressures of each element or molecule present in the vacuum chamber will improve our predictive abilities. This model will subsequently be extended to address arbitrary ion chain lengths, collisionally induced heating, the impact of micromotion, and site-selective cooling. We also hope to examine the impact of non-equilibrium gas dynamics in the proximity of surfaces (such as outgassing from the trap itself). The ultimate goal of this project is to create a computational model of collisional dynamics in linear ion traps that matches the observed phenomena including the anomalous scaling of re-ordering with longer ionic crystals. |
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V01.00064: Towards Ca+-assisted manipulation of Mg+ ions in a surface-electrode Paul trap Alejandra L Collopy, Hannah M Knaack, Laurent J Stephenson, Christina M Bowers, Andrew C Wilson, Dietrich Leibfried, Daniel H Slichter We discuss progress towards implementing mixed-species operation of Ca+-Mg+ ion crystals in a surface-electrode radio-frequency trap. The trap has been used to demonstrate universal laser-free control of single and multiple Mg+ ions using trap-integrated current-carrying electrodes [1]. Doppler cooling for Mg+ is performed with 280 nm ultraviolet light which can cause significant trap charging and thus rapid drifts in the ions' motional frequencies. By introducing a `helper' Ca+ ion, quantum logic techniques based on rf and microwave magnetic field gradients can be used for sympathetic cooling, as well as state preparation and readout, of a co-trapped `data' Mg+ ion using the ions' shared motional modes [2], without requiring 280 nm light. By removing the need for lasers addressing the Mg+ ion (apart from a photoionization beam), trap charging effects can be significantly reduced and decoherence of the `data' ion from light that is used to manipulate the Ca+ ion will be minimal. We have been adding features to our Ca+ ion toolkit at our operating magnetic field of 212.8 G while working towards multi-ion crystal cooling and internal state manipulation. |
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V01.00065: Progress towards a quantum network of 40Ca+ ions trapped in a surface-electrode trap with an integrated fiber-based optical cavity Katie David, Margie Bruff, Jules M Stuart, Lindsay Sonderhouse, Andrew C Wilson, Daniel H Slichter, Dietrich Leibfried Although there has been significant progress towards creating useful quantum computers, no practical way to generate the remote entanglement that is required to share quantum information has been demonstrated. Entanglement shared over a quantum network could enable increased quantum computational power, bolster communication security, and enhance the performance of quantum sensors. One quantum networking framework utilizes nodes comprised of trapped ions as local memory qubits, interconnected with telecom-wavelength photonic flying qubits. Trapped ions are a favorable stationary qubit due to their long coherence times, precise controllability, and easily configurable interactions, while telecom-wavelength photons make ideal non-stationary qubits because of their low optical fiber transmission losses. Here we report on our progress to more efficiently and robustly combine telecom-wavelength photonic qubits with trapped ion qubits by trapping 40Ca+ ions in a fiber Fabry-Perot optical cavity that is integrated into a surface-electrode trap. In this way, we hope to create high-fidelity, high-rate entanglement between ions and difference frequency generated 1550 nm wavelength photons for long-distance entanglement distribution. |
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V01.00066: Towards simulation of coherent and dissipative processes using metastable states in Ytterbium ions Midhuna Duraisamy Suganthi, Visal So, Mingjian Zhu, Abhishek Menon, April Sheffield, Roman Zhuravel, Guido Pagano Trapped ions offer a platform for quantum simulation of spin and spin-boson models with high control over the Hamiltonian parameters. In particular, Ytterbium ions feature several metastable atomic states that can be used for multiple purposes ranging from sympathetic cooling to coherent manipulations. This project focusses on using the S1/2 to D3/2 quadrupole transition in two ways: the first one is to implement σzσz spin-spin interactions on clock states of Yb+ ions[1]. We discuss a setup wherein a spatial light modulator is used to generate beam shaped arrays that can couple to axial modes of motion with beams orthogonal to the trap axis[2]. Combining this scheme with σxσx and σyσy Molmer-Sorensen gates will enable us to simulate the Heisenberg-XYZ model. The second goal is to use the D3/2 state for resolved sideband cooling of motional modes. By trapping ions of different species, we can sympathetically cool the collective motional states by addressing just one ion species while coherently manipulating the others. The Hamiltonian of such a system can be mapped onto a driven two-level system interacting with an engineered bath[3]. To address this narrow transition, we need to ensure that the linewidth of the laser is reduced to at least a few kHz. Therefore, we discuss the laser locking setup to an Ultra-Low Expansion (ULE) cavity, its stabilization and characterization of the quadrupole transition in Yb+ ions. |
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V01.00067: Investigation of sympathetic cooling for an ion trap quantum computer with 9Be+ and 40Ca+ Markus Duwe, Ludwig Krinner, Sascha Agne, Christian Ospelkaus One important source of finite infidelities in trapped-ion quantum logic gatesis due to the heating of motional modes [1]. One possibility to reduce this error source is the use of additional, ancillary ions to cool the logic ions prior to gate operations [2]. The logic ions can then be cooled indirectly via the Coloumb interaction while preserving the internal quantum states. We examine the choice of 9Be+ as logic ions along with 40Ca+ as ancilla ion for the QVLS Q1 project. Due to the unfavorable mass ratio, the coupling of the normal modes is vanishingly small and therefore the interaction between the ions reduced. We study the expected cooling rates and discuss possibilities, such as parametric coupling [3], to achieve cooling times that are sufficient for quantum computing. Other choices of logic- and ancilla ions are discussed. |
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V01.00068: Pulsed excitation and shelving schemes for 138Ba+ ion-photon entanglement generation Isabella Goetting, Mikhail Shalaev, Jameson O'Reilly, George Toh, Sagnik Saha, Tingguang Li, Christopher R Monroe The scaling of trapped ions in a single ion trap zone is hampered by spectral crowding, the increased susceptibility to background gas collisions, and complicated optical addressing setups. To avoid these problems, we envision connecting smaller trapped-ion quantum computers through optical links of single photons, allowing for quantum entanglement of separated ion chains. We use 138Ba+ as a communication ion because it has a relatively long-wavelength S1/2 to P1/2 transition and is therefore the most amenable to integrated photonic technologies. The main limitation in this solution is the entanglement generation rate, which previously was limited by optical pumping to the D3/2 state, so our goal is to increase this rate by exciting directly from the S state. We present details about a new single-photon generation scheme using a pulsed laser source at 493 nm for the S to P transition in 138Ba+ and an electron-shelving detection scheme using the narrow 1762 nm transition from S1/2 to D5/2. |
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V01.00069: Building a Stylus Trap and Deep Parabolic Mirror to Study and Control Quantum Jumps Jane Gunnell, Carl Thomas, Boris Blinov We present a method for studying quantum jumps in trapped barium ions using a "stylus" trap and deep parabolic mirror. This novel design minimizes the solid angle blocked by the trap structure allowing ~95% of the photons from the ion to hit the surrounding mirror. The trapped ion will sit at the focus of the mirror, and a lens will focus the collimated fluorescence onto avalanche photodiodes. This experimental design results in a total single photon detection efficiency of about 65%. |
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V01.00070: A long chain trapped-ion systems with in situ mid-circuit measurement Lewis Hahn, Sainath Motlakunta, Nikhil Kotibhaskar, Anthony Vogliano, Chung-You Shih, Jingwen Zhu, Kazi Islam, Yu-Ting Chen Trapped-ion system is a promising platform for quantum information processing (QIP). Previous research has demonstrated QIP of long-range spin physics with a long chain of ions (~50), however performing in-situ mid-circuit measurement was previously challenging for the field. Here we show the developments of our segmented blade trapped-ion system for a long ion chain. To achieve low neighbouring crosstalk while performing in-situ mid-circuit measurements, we will implement two, NA=0.5 imaging systems with photon time-tagged detection, paired with an aberration corrected addressing beam. Careful optical engineering and custom home-made compact optics breadboards will provide long term stability of our system. Through optimized vacuum engineering and extensive outgassing tests, low background collision rates will be achieved by reaching vacuum pressures that are projected to be an order of magnitude lower than current room-temperature trapped-ion QIP devices. This device will allow us to perform a wide range of QIP experiments, like measurement-based quantum simulations of spin Hamiltonian’s and hybrid digital-analog quantum algorithms. |
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V01.00071: Expanding the set of native ion-ion interaction graphs for quantum simulation Ilyoung Jung, Frank G Schroer IV, Antonis Kyprianidis, Alexander Rasmusson, Philip Richerme Trapped-ion quantum simulators generate pair-wise interactions by using spin-dependent optical dipole forces to couple to the motional modes of the ion crystal. While it is common for trapped-ion quantum simulations to host fully-connected interactions which decay algebraically with distance, such interactions are not a fundamental limitation of trapped-ion simulations. Here, we show a suite of achievable interaction graphs in both 1D and 2D which may be generated either by selective coupling to specific vibrational modes or by arranging the ions to be equally-spaced along the trap axis. To this end, we investigate a monolithic trap design that allows for a much more expansive set of 1D and 2D interaction graphs compared to traditional ion-trap quantum simulation approaches. |
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V01.00072: stability of trapped ions in paul trap with rotating bias field Urban Kobal, Will Jefferies, Matt Grau We investigated the motion and stability of ions in a radiofrequency trap with rotational bias field. Beginning with the extensively studied stability diagram for the Paul trap given by solutions to the Mathieu equation, we look for regions of instability created by the resonant electric field term. Additionally, we examine the effect of the bias field on laser-cooling in the trap. We also report on the design of an ion trap optimized for precision measurements of nuclear CP-violation in molecular ions. |
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V01.00073: Towards single site addressing of ions in a Penning trap Jennifer F Lilieholm, Bryce B Bullock, Allison L Carter, Anthony M Polloreno, Ana Maria Rey, John J Bollinger We describe recent experimental progress towards single site addressing of single plane arrays of several hundred ions generated in a Penning trap. Penning traps utilize a combination of static electric and magnetic fields to confine ions, however this induces an overall rotation of the crystal that makes individual addressing of the ions challenging (rotation frequency ~180 kHz). We are implementing a deformable mirror (DM) to generate wavefront deformations in a laser beam whose waist is large compared to the ion crystal radius. This altered beam is interfered with another co-propagating beam, resulting in the generation of an AC Stark shift intensity pattern. Setting the difference frequency of the two beams to multiples of the rotation frequency allows the creation of programable AC Stark shifts that are stationary in the rotating frame of the ion crystal and can thus target single ions with a fine enough control over the DM surface [1]. |
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V01.00074: Design and Characterization of a Monolithic Three-Dimensional Ion Trap Henry Luo, Michael Straus, Norbert M Linke Trapped ions are a leading platform of quantum computation and quantum simulation. Innovations in ion trap architecture in recent years have led to the scaling up, and improved performances of trapped ion quantum devices. A three-dimensional (3D) ion trap benefits from deep and symmetric trapping potentials, low heating rates, and good shielding from stray electric fields. In this work, we present a novel monolithic 3D ion trap microfabricated from a single piece of fused silica, developed in collaboration with Translume Inc and Rice University. The segmented blades are precisely machined to produce a homogeneous trapping potential along the center axis of the trap. We characterize the trap performance. We also discuss the applications of the trap and future upgrades to the trap design. |
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V01.00075: Control over phonons shared between three trapped ions in a two-dimensional microtrap array Nathan K Lysne, Justin F Niedermeyer, Andrew C Wilson, Daniel H Slichter, Dietrich Leibfried Two-dimensional arrays of ions trapped in individually addressable microtraps are promising systems for simulation. In such arrays, a single motional excitation in the array can be understood either as site-localized phonons with beamsplitter-like interactions or as shared non-local normal modes. By coherently controlling these excitations, one may be able to generate multipartite entangled states of the ions as well as study of many-body phenomena such as spin frustration and bosons evolving in synthetic magnetic fields. To realize a minimal such two-dimensional array, we have developed a surface-electrode ‘triangle trap.’ Operated at cryogenic temperatures, this device creates a triangular array of individual trapping sites spaced 30 µm apart with sufficient degrees of freedom to independently control the motional mode frequencies and orientations of an ion trapped in each potential. In this poster, we first discuss how we control the internal and motional states of individual 9Be+ ions in the array. We will then share recent results on coherent operations between adjacent ions in the array, including a demonstration of over 100 exchanges of a single phonon between ions achieved by tuning motional mode frequencies into resonance through control over individual site curvatures. Finally, we extend this control over the full array, demonstrating hybridization into shared motional modes as well as controlled reintroduction of a single phonon after cooling to the approximate motional ground state. |
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V01.00076: Quantum Logic of Molecular States through Electric-field Gradients on a Cryogenic Ion Trap Grant D Mitts, Clayton Z Ho, Hao Wu, Eric R Hudson The rich state space of dipolar molecular ions in the microwave (MW) regime offers an intriguing laser-free platform to realize universal quantum gates. It was recently shown (PhysRevA. 2021, 104, 042605) that phonon-mediated quantum gates can be achieved by applying quadrupole microwave electric fields gradients via the electrodes of an ion trap, so called electric field gradient gates (EGGs). In order to suppress the chemical reaction due to background gas and reduce the blackbody radiation (BBR) for better rovibrational quantum state control, we have developed a cryogenic Paul trap with <30 nm displacement due to vibration at the ion trap. We have succeeded in cotrapping HCl+ with Ca+ in an ion chain. Moreover, we have applied sideband cooling and been able to cool all the motional modes less than 0.1 phonon. Finally, we will discuss how to use this new platform to pursue EGGs. |
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V01.00077: Experimental method for evaluating two-qubit gate infidelity due to noise Elia Perego, Nicole S Greene, Hartmut Haeffner The ability to entangle two qubits with high-fidelity gates is fundamental for realizing quantum computing systems. However, these gates are performed in environments where the experimental parameters not only can suffer from static offsets, but also change over time. The detrimental effect of time-varying noise on the coherence can be quantitatively described with the filter function formalism, although it cannot effectively capture the gate infidelity for noise frequencies lower than the inverse of the gate time [1]. |
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V01.00078: Towards all-electronic control of trapped ion qubits Raghavendra Srinivas, Clemens M Löschnauer, Maciej Malinowski, Amy C Hughes, Rustin Nourshargh, Marius A Weber, Vlad Negnevitsky, David T Allcock, Steven A King, Clemens Matthiesen, Thomas P Harty, Chris J Ballance We outline progress towards all-electronic control of trapped ion qubits at Oxford Ionics. In particular, we present a new technique we developed to control ions in separate interaction regions of a multi-zone trap. We use an electric field, which can be localized to each zone, in combination with a spin-dependent gradient to perform single-qubit rotations. Both the phase and amplitude of the rotation can be controlled using the electric field. We demonstrate this interaction on a single ion using both laser-based and magnetic field gradients in a surface-electrode ion trap, and measure the localization of the electric field. |
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V01.00079: Towards a 16-qubit trapped barium ion testbed. Hawking Tan We present our progress towards trapping and manipulating Ba-133 ions on a surface trap. The [KI1] vacuum chamber (4E-11 mbar) provides high NA optical access from multiple directions for fluorescence collection and optical manipulation in a Phoenix surface trap fabricated by Sandia National Laboratories. Visible wavelength atomic transitions in Ba+ offer unique possibilities to adapt waveguide optics for modularity and scalability. We demonstrate a single-qubit optical addressing scheme with independent amplitude, frequency, and phase control and low (~1E-4) relative intensity crosstalk at the location of neighboring qubits. This scheme leverages laser-written waveguides, fiber modulators, and microlens arrays. We also present results from our effort to create efficient laser-ablated atomic sources for radioactive Ba-133 ions. |
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V01.00080: Advances in the control and manipulation of 133Ba+ Qubits Samuel Vizvary, Zachary J Wall, Matthew Boguslawski, Wesley C Campbell, Eric R Hudson We present advances in trapped ion quantum computing by utilizing state mixing at non-zero magnetic fields to achieve "magic conditions," which result in a significant increase in qubit coherence time when exposed to high power lasers. Our study of the 133Ba+ trapped ion qubit highlights its exceptional qubit state preparation and measurement (SPAM) fidelity and its unique features, including optical and long-lived metastable qubit states. Our results demonstrate new capabilities for manipulation between qubit states and progress towards implementing single and two qubit gates, offering potential for practical applications in quantum computing. |
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V01.00081: Towards precision spectroscopy on single trapped molecular ions Fabian Wolf, Maximilian J Zawierucha, Till Rehmert, Piet O Schmidt We are currently setting up an experimental apparatus for the investigation of molecular ions. The main goal of the experiment is precision spectroscopy on a vibrational overtone transition of a single molecular ion to probe for new physics effects such as a possible variation of fundamental constants. For this purpose, we are implementing quantum logic spectroscopy that was already successfully used for the aluminum optical clock [1] and the first clock based on highly charged ion [2]. We plan to implement a modified version of the classical quantum logic spectroscopy by using optical forces from bichromatic Raman interactions on the molecular ion, that allow to entangle the internal state of the molecule with the motional state [3]. The motional state is shared between the molecule and a co-trapped atomic ion and can therefore be used as a bus to transfer information from one ion to the other. Detection of the motional excitation on the atomic ion will allow us to infer the molecules internal state [4]. |
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V01.00082: Compact acousto-optic deflector individual addressing system for trapped-ion quantum computers Jiyong Yu, Ke Sun, Jungsang Kim Abstract body |
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V01.00083: Trapped O2+ Reactions with C3H4 Isomers Chase Zagorec-Marks, Olivia Krohn, Trevor Kieft, Heather J Lewandowski Cold ion-neutral reactions within laser-cooled trapped ion ensembles are a powerful model system for studying the fundamental dynamics of chemistry present in the Interstellar Medium (ISM). Laser-cooled ions allow us to sympathetically cool molecular ions thereby translationally cooling the reactants to temperatures similar to the ISM. Time-of-flight mass spectroscopy enables us to monitor the temporal evolution of reactions and measure product branching ratios. Recently we investigated the reaction between the O2+ cation and the C3H4 isomers, propyne (HC3H3) and allene (H2C3H2). Measurements show significant differences in the reaction dynamics and kinetics of these two reactions. These measurements are supported through the use of isotopologue substitution and quantum chemistry calculations. This work builds on previous isomer-specific reaction studies and contributes to the knowledge of ion-molecule reactions relevant to the ISM. |
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V01.00084: Towards the Creation of Degenerate Fermionic/Bosonic NaK Molecular Gases with Long-range Dipolar Interactions Jaeryeong Chang, Sungjun Lee, Yoonsoo Kim, Younghoon Lim, Jee Woo Park Ultracold quantum gases are an ideal testbed for simulating complex many-body quantum behavior. Especially, the creation of degenerate gases of dipolar molecules will give access to novel quantum phases of matter such as exotic superfluids and quantum crystals, and will also realize quantum computing platforms based on molecular qubits. |
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V01.00085: Strongly correlated 2D ensembles of bosonic polar molecules Lysander Christakis, Jason S Rosenberg, Ravin Raj, Zoe Z Yan, Youssef A Alaoui, Waseem S Bakr Ultracold molecules are a promising candidate for the quantum simulation of many-body physics. Equipped with long-range interactions and a plethora of long-lived internal states, they can be prepared, controlled and probed using quantum gas microscopy techniques. In recent work, we demonstrated the site-resolved measurement of correlations between ultracold NaRb molecules in a 2D optical lattice [1]. Prepared in an out-of-equilibrium state, the molecules naturally realize the 2D quantum XY model with long-range interactions. The growth of spatial correlations in the thermalization process was read out using a site-resolved Ramsey interferometric technique. Through Floquet engineering using periodic microwave pulse sequences, we also simulated the correlation dynamics of a spin-anisotropic Heisenberg model. We now plan to further cool the molecules through forced evaporation in a bulk trap. Reactive collisional losses between the molecules are heavily suppressed by van der Waals interactions, which are carefully tuned using an external DC electric field. Near a rotational Forster resonance, we demonstrate one-body loss limited molecule lifetimes of several seconds in a bulk trap. Evaporation of the shielded molecules will enable the preparation and study of strongly correlated phases in the extended Bose-Hubbard model. |
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V01.00086: The effects of nonadiabatic physics in long-range Rydberg molecules Matthew T Eiles, Frederic Hummel, Neethu Abraham, Peter Schmelcher
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V01.00087: Creation of an Ultracold Gas of Ground State Dipolar 6Li40K Molecules Xiaoyu Nie, Canming He, Victor Andre Avalos Pinillos, Sunil Kumar, Sofia Botsi, Anbang Yang, Kai Dieckmann Creation of dipolar molecules in the ro-vibrational ground state is a long-standing scientific goal and has been achieved. Such molecules are promising platforms for precision measurement, quantum simulations of many-body systems, and quantum bit manipulation based on the dipole-dipole interaction. Ultracold 6Li40K molecules in the deeply-bound ro-vibronic states possess a large electric dipole moment (3.6 Debye). This makes them a suitable candidate for exhibiting strong effects of the long-range and anisotropic nature of the dipole-dipole interactions. |
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V01.00088: Chaotic scattering and microwave loss suppression in the NaRb system Zhaopeng Shi We report two recent results on atom-molecule and molecule-molecule collisions in the ^{23}Na^{87}Rb system. In the former case, we observe in total over 100 Feshbach resonances between ^{87}Rb atoms and ground-state ^{23}Na^{87}Rb molecules. A preliminary statistical analysis reveals that the chaotic distribution of these resonances. In the latter case, we use microwave dressing to suppress the loss induced by the complex formation and achieve a two-body loss rate coefficient of 9 * 10^{-13} cm^3s^{-1}. We also observe enhanced elastic collision rates as high as 2 * 10^{-9} cm^3s^{-1}. The large elastic to inelastic ratio should allow efficient evaporative cooling toward NaRb samples with higher phase space densities. |
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V01.00089: Progress towards a 3D MOT of CaH molecules Qi Sun, Jinyu Dai, Issac Pope, Debayan Mitra, Tanya Zelevinsky Direct laser cooling and trapping of molecules has enabled new possibilities in the fields of precision measurement, quantum information processing, and ultracold chemistry. Calcium monohydride (CaH) is a promising candidate for producing a dilute cloud of hydrogen atoms for spectroscopy and other applications. In order to slow the molecules down to the MOT capture velocity, it is important to achieve efficient optical cycling and dark state repumping. However, a nonradiative decay pathway, predissociation, could limit the ability to do so in a number of molecular species including CaH. Here we describe measurements of the predissociation rate of the B state in CaH, and demonstrate that predissociation does not limit our ability to make a 3D MOT. We also report our progress on direct laser slowing and trapping of CaH. This work validates a technique we developed to characterize molecular predissociation and provides insights on extending laser cooling techniques to other molecules that suffer from predissociation. |
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V01.00090: Towards quantum degeneracy in a 88Sr19F molecular gas Qian Wang, Thomas K Langin, Varun Jorapur, Geoffrey Zheng, David P DeMille Despite the recent progress in direct cooling and trapping of molecules, the phase-space density of these systems is still low compared to atomic systems. This is due in large part to inefficient slowing, low magneto-optical trap (MOT) capture velocity, and sub-Doppler heating in the traditional red-detuned MOT. Such heating is a result of molecules’ type-II transition, where the excited state total angular momentum is less than or equal to the ground state angular momentum. Here, we present new methods to mitigate these issues. |
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V01.00091: Collisional Studies of NaCs Molecules Weijun Yuan, Niccolò Bigagli, Claire Warner, Siwei Zhang, Ian C Stevenson, Sebastian Will Obtaining a detailed understanding of loss processes in ultracold molecular gases is a key frontier of the field and a direct link to quantum chemistry. So far, experimental findings have been ambiguous. Some experiments show strong evidence that molecules are lost when long-lived four-body collisional complexes are excited by trap light, while other experiments do not. Newly available ultracold NaCs molecules offer a valuable data point in this fast-evolving field. First, we report on an efficient STIRAP pathway to the molecular ground state. Next, we study the collisional properties of NaCs molecules. Using a modulated dipole trap with dark times of up to 1.5 ms, we do not see evidence for the excitation of complexes via trapping light. Further enhancing the detection sensitivity, we have implemented an approach to study NaCs molecules in the absence of trapping light for longer periods of time. These measurements exclude (NaCs)2 complex lifetimes below 100 ms. Finally, we measure the temperature dependence of the two-body loss rate of NaCs molecules and observe loss rates larger than the universal relation. We thus speculate that the RRKM theory of collisional complex lifetimes may not apply to the case of NaCs. |
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V01.00092: Microwave Dressing of NaCs Molecules Siwei Zhang, Niccolò Bigagli, Claire Warner, Weijun Yuan, Ian C Stevenson, Sebastian Will We report on studies of microwave-dressed ultracold sodium-cesium (NaCs) molecules. Using a phased antenna array, we dress the NaCs molecules with strong and circularly polarized microwave fields. We present the design of the array, with which we achieve up to 46 MHz Rabi coupling between the lowest two rotational states, and 4 degree polarization ellipticity. We demonstrate that, under the dressing field, the properties of the molecules fundamentally change. The inelastic loss is reduced by a factor of 200. The elastic cross-section increases because of the dipolar nature of the collisions. The optical ac polarizability of molecules changes. This change creates a magic transition between the two dressed states, even though no such magic transition exists in the bare molecule. These studies demonstrate that dressed molecules are fundamentally different from undressed ones, and encourage further investigations of this kind. |
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V01.00093: STRUCTURE AND PROPERTIES OF ATOMS, IONS, AND MOLECULES
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V01.00094: Effects of Magnetic Fields on Photoexcitation of 86Sr ultralong-range Rydberg Molecular Dimers Chuanyu Wang, Yi Lu, Soumya K Kanungo, Tom C Killian, F B Dunning In this poster we present an experimental study of the effects of magnetic fields of up to 5 Gauss on photoexcitation of ultralong-range Rydberg molecular dimers in an ultracold atomic gas of 86Sr for low principal quantum numbers (n~30) and excitation to triplet Rydberg states 5sns 3S1. Transitions to individual molecular rotational states are resolved. The excitation rates for different angular momentum states vary dramatically as a function of the applied field, suggesting a Rydberg atom or molecular spin interaction with the magnetic field that has not been observed before. Such variation is not observed in 84Sr. Rydberg molecules are photoexcited through 2-photon excitation using 689nm and 320nm lasers that are stabilized by locking them to a high-finesse optical cavity. |
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V01.00095: COLD ATOMS, IONS, MOLECULES, AND PLASMAS
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V01.00096: A Reconfigurable Optical Tweezer Array of CaF Molecules: Progress towards Full Quantum Control Samuel J Li, Connor M Holland, Yukai Lu, Lawrence W Cheuk In this poster, we report on progress towards fully controlling laser-cooled CaF molecules in an optical tweezer array. Specifically, we present work on initializing the internal state and spatial configuration of the molecules. With relevance to simulating interacting quantum systems and quantum information processing, we also report on observing coherent interactions between individual molecules, and the on-demand entanglement of molecules into Bell pairs. Looking ahead towards using molecular tweezer arrays as a competitive platform for quantum science, we discuss factors that limit the achieved state preparation and entanglement fidelities, and the pathways towards higher fidelities. |
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V01.00097: Progress towards magneto-association of ultracold LiCs molecules in optical tweezers Saumitra S Phatak, David Peana, Karl Blodgett Ultracold molecules have the potential to serve as qubits, owing to their high fidelity, strong interactions and long coherence times. By harnessing the control of a tweezer array with both atoms and molecules, we aim to create a versatile platform for many-body Hamiltonian engineering. In our lab, we trap and cool single Lithium and Cesium atoms to below the Doppler limit. Our goal is to form a tweezer array of these ultracold Li and Cs atoms and cool them even further to nanokelvin temperatures. We will then combine these atoms into LiCs molecules through magneto-association, which will be used for quantum computing, simulation, and chemistry applications. This poster presents an overview of our lab's recent progress. |
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V01.00098: Towards fermionic open-shell RbSr molecules Premjith Thekkeppatt, Digvijay Digvijay, Simon Lepleux, Junyu He, Klaasjan van Druten, Florian Schreck Ultracold dipolar molecules are a promising platform for quantum simulation, precision measurement and quantum chemistry. Ultracold molecules produced so far are closed-shell molecules, which limits their range of applications. Our goal is to produce ultracold fermionic RbSr molecules, which are dipolar open-shell molecules, in order to extend the range of possibilities. |
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V01.00099: PRECISION MEASUREMENT
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V01.00100: A Compact Optical Fiber Magnetometer for Irradiated Environments Joshua B Abney, Michal Cwik, Joel M Hensley Circuit components exposed to high intensity, pulsed X-ray radiation experience internal and external Electromagnetic Pulse (EMP) effects that create large currents that cause damage to individual components. These currents generate magnetic fields within the device and knowledge of these magnetic fields is important to validate models of a particular component’s response to EMP effects. Presently, these fields are measured with small induction coils that are limited by electromagnetic interference susceptibility, finite size constraints, and proximity within a test object. The Compact Optical Fiber for Extreme Environments (COFFEE) system describes a low profile sensor that measures magnetic fields based on the Faraday effect in a small section of rare earth ion doped fiber. The system will be capable of capturing the transient magnetic field effects on the relevant nanosecond timescales while the optical fiber based sensor will be more robust to EMI and X-ray radiation than traditional induction coils. Initial results with the magnetometer and progress towards the complete system will be discussed. |
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V01.00101: Dual tone RF dressing in Rydberg EIT for electric field sensing Maitreyi Jayaseelan, Andrew P Rotunno, Kaleb Campbell, Nikunjkumar Prajapati, Samuel Berweger, Alexandra B Artusio-Glimpse, Matthew T Simons, Christopher L Holloway Over the last decade, Rydberg electromagnetically-induced transparency (EIT) has been shown to be a versatile tool for sensitive electrometry in the radio frequency (RF) regime. These sensors have used the Rabi frequency-dependent Autler--Townes splitting of Rydberg energy levels driven by a single frequency RF field to characterize electric fields through their amplitude, phase, polarization, and more. Here we examine Rydberg EIT spectra in a configuration where the Rydberg atoms are dressed with a dual tone RF field. When the two RF frequencies are close to, but detuned from, a Rydberg resonance, the spectra reflect the more complex atomic response to the dual-field interaction than that observed with a single frequency RF dressing field. For instance, we can observe spectra where the separation between the peaks is controlled by detunings of the RF fields and is independent of the Rabi frequencies. We characterize the dual-tone dressed system through the Floquet quasi-energies and modes as we vary the frequencies and powers of the two RF fields independently. We discuss potential applications of the system, including the possibility of detecting the frequency and power of an unknown RF field and implications for Rydberg sensors in cluttered RF environments. |
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V01.00102: High-precision measurements of atomic structure in lead and other multi-valence atomic systems Protik K Majumder, John Lacy, Russell Blakey, Abby Kinney, Charles Yang Recently, we used a Faraday rotation spectroscopy technique with microradian precision to complete the first ever direct measurement of the forbidden electric quadrupole (E2) transition in Pb at 939 nm. Comparing its transition amplitude to the magnetic dipole (M1) transition, we found excellent agreement with the theoretical value predicted from new ab initio calculations in Pb1. Since then, we have developed our apparatus to perform Faraday spectroscopy in the blue and near-UV which compare quantum-mechanical linestrengths between transitions starting from the ground state and those originating from low-lying thermally-excited states. Currently we are completing precision measurements of the 368 nm (6p2) 3P1 - (6p7s)3P0 and the 406 nm (6p2) 3P2 - (6p7s)3P1 E1 transition amplitudes using samples in quartz vapor cells at precisely controlled temperatures. We again use the ground-state M1 transition for normalization/comparison, noting that the E1 transitions originate from states whose small Boltzmann population almost exactly compensate for the intrinsic E1/M1 linestrength differences. In parallel work, and following up on previous work with thallium and indium2, we are also pursuing new measurements of lead polarizability using our high-flux atomic beam apparatus, high-voltage field plates, and a transverse Faraday rotation spectroscopy arrangement. We plan to extend both sets of measurements in Pb to other multi-valence atomic systems such as thallium and barium, providing further new benchmark tests of state-of-the-art atomic structure calculations. Current results will be presented. |
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V01.00103: Precision spectroscopy of the 2S-6P transition in atomic hydrogen and deuterium Lothar Maisenbacher, Vitaly Wirthl, Arthur Matveev, Alexey Grinin, Derya O Taray, Omer Amit, Randolf Pohl, Thomas Udem, Theodor Hansch Both atomic hydrogen and deuterium can be used to determine physical constants and to test bound-state quantum electrodynamics (QED) to very high precision. By combining at least two transition frequency measurements in each isotope, the proton and deuteron radius, along with the Rydberg constant, can be determined independently [1]. This is particularly interesting because, while recent hydrogen measurements [2] have agreed with the results from muonic hydrogen, no recent deuterium measurements are available and a discrepancy with muonic deuterium persists [3]. |
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V01.00104: Anthropic constraint on transient variations of fundamental constants Hoang Bao Tran Tan, Sergey A Varganov, Vsevolod Dergachev, Andrei P Derevianko The anthropic principle implies that life can emerge and be sustained only in a narrow range of values of fundamental constants. Here we show that anthropic arguments can set powerful constraints on transient variations of the fine-structure constant α over the past 4 billion years since the appearance of lifeforms on Earth. We argue that the passage through Earth of a macroscopic dark matter clump with a value of α inside differing substantially from its nominal value would make Earth uninhabitable. We demonstrate that in the regime of extreme variation of α, the periodic table of elements is truncated, water fails to serve as a universal solvent, and protons become unstable. Thereby, the anthropic principle constrains the likelihood of such encounters on a 4-billion-year timescale. This enables us to improve existing astrophysical bounds on certain dark matter model couplings by several orders of magnitude. |
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V01.00105: High-precision study of E1 transition amplitudes for single-valence atoms and ions Benjamin Roberts, Carter Fairhall, Jacinda Ginges Motivated by recent measurements of several properties of alkali metal atoms and alkali-like ions, we perform a detailed study of electric dipole (E1) transition amplitudes in K, Ca+, Rb, Sr+, Cs, Ba+, Fr, and Ra+, which are of interest for studies of atomic parity violation, electric dipole moments, polarisabilities, the development of atomic clocks, and for testing atomic structure theory. Using the all-orders correlation potential method, we perform high-precision calculations of E1 transition amplitudes between the lowest s, p, and d states of the above systems. We perform a robust error analysis, and compare our calculations to 43 amplitudes which have high-precision experimental determinations. We find excellent agreement, with accuracies at the level of 0.1% or better. |
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V01.00106: Progress on the Measurement of the Electric Dipole Moment of 171Yb Atoms Yang A Yang, Shao-Zheng A Wang, Tao A Zheng, Tian Xia, Zheng-Tian Lu The permanent electric dipole moments (EDMs) originatesoriginate from the sources of CP-violation. We present an experimental search for the EDM of the 171Yb (I=1/2) atom with atoms held in an optical dipole trap (ODT), and a coherent spin precession time of up to hundreds of seconds. By enabling a cycling transition that is simultaneously spin-selective and spin-preserving, a quantum non-demolition measurement allows spin detection near the shot-noise limit. A systematic effect due to parity mixing induced by a static E field is observed and is suppressed by averaging between measurements with ODTs in opposite directions. Our result places a limit of |dYb-171|< 1.5x10-26 e cm (95% C.L.). We describe and discuss several experimental upgrades, such as enhanced electric field strength, and suppressed magnetic field noise. Together, these upgrades are projected to increase the statistical sensitivity of the experiment by one order of magnitude. |
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V01.00107: Dark Matter Searches via Isotope Shift Spectroscopy with Trapped Ca+ Ions S. Charles Doret, Timothy Chang, Bless Bah Awazi, Renee DePencier Pinero, Sonya Dutton We present our latest results searching for new physics beyond the Standard Model via precision isotope shift spectroscopy on the 42S1/2→ 32D3/2 (732 nm) and 42S1/2→ 32D5/2 (729 nm) electric quadrupole transitions in Ca+. By making measurements amongst several isotopes on multiple transitions and generating a `King Plot' it is possible to reveal contributions to the isotope shifts which do not appear at first-order in the Standard Model. Violations of `King's Linearity' thus might indicate the signature of electron-neutron couplings arising from intermediate-mass gauge bosons in the dark sector, or provide an avenue into measuring higher-order effects arising within the Standard Model, such as nuclear polarizabilities, which have previously been inaccessible to experiment. Our ongoing experiments co-trap two isotopes and simultaneously excite both ions using frequency sidebands on a single laser, dramatically reducing systematic uncertainties from many sources such as laser frequency drift and magnetic field instabilities that have limited other related experiments. Present work on the 42S1/2→ 32D3/2 transition has reached few-Hz (part-per-billion) precision, a new level of sensitivity for tests of King's Linearity. |
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V01.00108: DESIRE - Dark energy search using atom interferometry in the Einstein Elevator Baptist Piest, Charles Garcion, Sukhjovan Gill, Magdalena Misslisch, Alexander Heidt, Ioannis Papadakis, Vladimir Schkolnik, Cheng-wey Chiow, Nan Yu, Ernst Rasel Light pulse atom interferometry is a promising tool to search for new microscopic forces on the dynamics of neutral atoms. The accuracy of such measurements scales with the square of the time between the atom interferometer laser pulses. On typical groundbased devices, it is therefore limited by the amount of available freefall time which is usually constrained by the size of the apparatus. One possibility to overcome this limitation is to use Bose-Einstein condensates (BECs) with ultralow expansion rates in microgravity. |
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V01.00109: A single strontium ion optical frequency reference for realizing accurate time Roger C Brown, Ladan Arissian, Thomas P Heavner, Guilherme de Andrade Garcia, Dave R Leibrandt, Jeffrey A Sherman Continuously running maser and cesium beam clock ensembles form the basis for most international time scales. On week to month averaging intervals, frequency drift in these devices must be corrected in order to maintain an accurate interval for the SI second. This is typically achieved via comparison with a primary or secondary frequency standard, eg. a Cs or Rb fountain. Here we present progress towards a secondary frequency standard based on the singly-forbidden, S_{1/2} -> D_{5/2}, optical transition in a RF-trapped strontium ion. In particular, we report a novel spherical Paul trap design compatible with low systematic uncertainty, progress on miniature Sr ovens, and a titanium UHV chamber design. This clock architecture can improve upon the accuracy and stability of a microwave fountain with less complexity than quantum-logic-interrogated ion and optical lattice clocks. |
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V01.00110: A common-mode approach for minimizing motion-induced frequency shifts in optical ion clocks Mark H Lide, Christian Sanner Reaching utmost accuracy with optical atomic clocks requires precise control over the motional degrees of freedom of the spectroscopically probed atoms. Especially for clocks based on trapped ions, the motional heating during the spectroscopic interrogation can lead to significant clock errors due to motion-induced Doppler shifts and Stark shifts. The cancelation of probe-light induced frequency shifts indirectly also depends on the ion's motional state. For the case of the 467 nm electric octupole clock transition in singly-charged ytterbium we analyze the combined effect of these shift mechanisms and describe new ways to characterize and minimize them. |
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V01.00111: Common-mode noise suppression of vector magnetometry using electromagnetically induced transparency Isaac Fan, Ying-Ju Wang, Yang Li, Mario Maldonado, Eugeniy E Mikhailov, Irina B Novikova, Jamie McKelvy, Andrey B Matsko, John E Kitching Warm vapor quantum sensors have shown sensitivity comparable to SQUIDs in measuring scalar magnetic field. Scalar sensors can be adapted to include measurement of magnetic field orientation but usually at the cost of scalar accuracy. Magnetometry using two-photon electromagnetically induced transparency resonances can provide both scalar accuracy and vector information but the limits to such measurements are not currently well-understood. Here we present a novel measurement scheme in multi-resonance EIT spectroscopy where the common-mode shifts of the resonance spectrum can be significantly suppressed by repeatedly probing the frequency difference between a pair of symmetrical resonances. Operating at the earth-like magnetic field strength of 50 μΤ, a <=200 pT/rtHz magnetometer sensitivity at 1 mHz and 10 pT/rfHz at 0.1 Hz has been achieved. |
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V01.00112: Frequency response of an open loop Bell-Bloom type atomic magnetometer in an Earth-scale magnetic field Sangkyung Lee, Minwoo M Kim, Ji Hoon Yoon, Sin Hyuk Yim, Taek Jeong We demonstrate a portable Bell-Bloom type atomic magnetometer for measuring an earth-scale magnetic field and investigate its frequency response in both theoretically and experimentally. The frequency response of an open loop atomic magnetometer is inversely proportional to the square root of the Lorentzian function with a width of the transverse relaxation rate when the amplitude of an magnetic field noise is very small. We discuss open loop frequency responses of the magnetometer in the presense of a strong AC magnetic field or a strong white magnetic field noise. |
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V01.00113: Angular momentum alignment-based magneto-optical signals for the detection of two orthogonal magnetic field components in atomic Cs. Arturs Mozers, Laima Busaite, Dace Osite, Antons Nikolajevs, Florian Gahbauer, Marcis Auzinsh We present a compact magnetometer that is sensitive along two orthogonal magnetic field components using two beams from the same laser source. We implement a pump-probe geometry from LeGal et al [1] where a linearly polarized (Ep) pump beam creates atomic alignment that interacts with the magnetic field (Bz) and the state of the system is probed by a linearly polarized (Es1) probe beam. The compactness of the method stems from the fact the required angle between the pump (kp) and probe (ks) beams is 35.3 degrees which in turn means that the light from both beams can enter the vapour cell from the same optical port. When an external magnetic field (Bz) is applied in a direction perpendicular both to Ep and Es1 the initially aligned state starts to precess around Bz. Because Es1 lies in the x-y plane and makes a π/4 angle with respect to the y-axis, the probe beam yields a dispersive dependence of the absorption on the transverse magnetic field component Bz. For the system to be senstive to magnetic field along x-axis (Bx) we rotate the polarization of the probe beam around ks until the Es1 lies in the z-y plane. We implement this rotation of the plane of polarization experimentally by the use of an electro-optic modulator. This enables us to detect two orthogonal components of the external magnetic field from a single experiment. |
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V01.00114: Optimization of a Single Beam All-optical Magnetometer using a microfabricated 87Rb Vapor Cell JiHoon Yoon, Sangkyung Lee, Sin H YIM, Taek Jeong, Hyun-Gue Hong, Sang E Park, Jongcheol Park We demonstrate a current-modulated single laser beam Bell-Bloom magnetometer measruing Earth-scale magnetic fields where a microfabricated gas cell with inner dimensions of 3 mm * 3 mm * 2 mm filled with a 87Rb vapor and nitrogen is applied. A current-modulated single laser beam drives the spin precession of 87Rb and the resulting spin precession induces the polarization rotation of the laser beam. By using balanced detection of the polarization-rotated laser beam, the spin precession can be observed. We investigate sensitivities of the magnetometer by varying detuning, averaged intensity, modulation depth, and polarization of the single laser beam in order to optimize the magnetometer. |
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V01.00115: Yb Atom Interferometers within an Optical Lattice: Multi-path Stuckelberg and Magic Depth Interferometry Tahiyat Rahman, Emmett Hough, Anna Wirth-Singh, Andrew Ivanov, Daniel Gochnauer, Charles Skinner, Subhadeep Gupta We report on multi-path Stuckelberg (MPS) interferometry in an ultracold atom system. Our atomic source is a BEC of {^174}Yb which is loaded into an optical lattice made from two counter-propagating laser beams with tunable frequency sweep suitable for an atom interferometer (AI) in a vertical fountain geometry [1]. The frequency sweep drives Bloch oscillations (BOs) of atomic momentum wherein the avoided crossing corresponding to each BO process is effectively a beam splitter where a Landau-Zener tunneling event between adjacent bands can occur, forming an in-lattice AI with 2^(N-1) paths where N is the number of BOs. We use MPS AIs to characterize BO phase shifts for precision interferometry [2]. We plan to extend in-lattice interferometry by pairing with operation at “magic depths”, where the average band energy is first-order insensitive to lattice depth fluctuations from intensity noise of the lattice beams [3]. Such magic-trapped atom interferometry can be applied towards precision gravimetry and equivalence principle tests. |
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V01.00116: Lattice atom interferometer in an optical cavity Cristian D Panda, Miguel Ceja, Andrew Reynoso, Matthew Tao, Holger Müller In quantum metrology and quantum information processing, a coherent nonclassical state must be manipulated before unwanted interactions with the environment lead to decoherence. In atom interferometry, the nonclassical state is a spatial superposition, where each atom coexists in multiple locations at once as a collection of phase-coherent partial wavepackets. These states enable precise measurements in fundamental physics and inertial sensing. However, atom interferometers usually use atomic fountains, where the available free-fall time sets a hard time limit on the interrogation of the quantum state. We instead realize atom interferometry with a coherent spatial superposition state held by an optical lattice for longer than 1 minute, which is more than 25 times longer than any atomic fountain interferometer. This performance was made possible by recent advances in the understanding and control of coherence-limiting mechanisms. An order of magnitude increase in sensitivity enables near-term applications such as gravimetry measurements, searches for fifth forces, or fundamental probes into the non-classical nature of gravity. |
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V01.00117: Optimizing a guided atom interferometer using machine learning Ceren Uzun, Michael McKerns, Katarzyna Krzyzanowska, Saurabh Pandey, Michael J Martin, Malcolm G Boshier Atom interferometers that are based on Bose-Einstein condensates (BEC) are useful in sensing rotations. We realize our Sagnac atom interferometer by splitting, reflecting, and recombining the condensate with a sequence of standing-wave Bragg pulses inside a waveguide that is transversely translated. Two important factors impacting the performance of such a device are a delta-kick cooling (DKC) procedure and the precise timing between the reflection pulses (mirror-mirror timing). These factors control the collimation of the wave-packets during the interferometer interrogation cycle and the overlap of the wave-packets at recombination, respectively. Manual optimization of the experimental parameters related to these factors is often time-consuming and challenging because the parameters are not independent. Moreover, recent studies have demonstrated that many machine learning (ML) schemes may significantly outperform manual tuning efforts in complex cold atom experiments and they do so in much shorter times. We demonstrate a guided atom interferometer implemented into an automated learning scheme which can be called as a subroutine. Our ML workflow is designed to minimize the number of calls to the experiment for faster optimization. We are applying ML optimization to the various stages of BEC generation as well as the DKC and mirror-mirror timing parameters of our guided atom interferometer. |
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V01.00118: Optically-addressable organic molecules for precision tests of fundamental constant variation Zack Lasner, Benjamin Augenbraun, John M Doyle We identify a set of organic molecules as promising candidates for the measurement of variations in the proton-to-electron mass ratio, μ. Since rotational and vibrational energies of molecules are inherently sensitive to μ, oscillations in μ induced by certain dark matter models would cause oscillation in the resonance frequency of rovibrational transitions. One candidate molecule, glyoxal (C2H2O2), is discussed in detail. The near-degenerate symmetric and antisymmetric O-C stretching vibrational states serve as "science states" that can be probed with low-power and low-frequency microwave radiation in a Ramsey measurement. With a vapor pressure of >250 Torr at 25 C, purified glyoxal can be seeded with high flux into a cryogenic molecular beam source for large statistical sensitivity. The science states can be populated using quantum cascade lasers, and convenient optical transitions at visible wavelengths enable efficient, state-selective laser-induced fluorescence readout. Due to its high degree of symmetry and closed-shell electronic structure, glyoxal is robust against systematic errors associated with electromagnetic fields. Extensions of the proposed method can satisfy additional experimental criteria with the suitable choice of an alternative molecule. For example, benzonitrile-d5 possesses a large molecular dipole moment, which makes it suitable for electrostatic focusing or deceleration which may further increase statistical sensitivity. |
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V01.00119: ULTRAFAST AND STRONG FIELD PHYSICS
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V01.00120: Ultrafast nonadiabatic relaxation of C60 with decoherence: DFT versus extended tight-binding model Matthew Wholey, Ruma De, Mohamed El-Amine Madjet, Esam Ali, Himadri Chakraborty Nonadiabatic relaxation of photoabsorbed fullerene materials are relevant in electron transport and cooling processes. In this work, we use an approach of electron-phonon coupled nonadiabatic molecular dynamics (NAMD) [1] to simulate the relaxation of molecular C60. The methodology relies on a combination of the fewest-switch surface hopping approach and Kohn−Sham single-particle description in density functional theory (DFT) [2]. In this scheme, when nuclear wavefunctions for different electronic states sufficiently separate, the quantum mechanical coherence between the components of electronic wavepackets should cease to exit creating a decoherence condition [3], the effect of which is not clearly known for C60. We will present the results of the femtosecond evolution of various excited and intermediate states by including this decoherence effect. We will further compare the results of PBE exchange-correlation functional in DFT with rather inexpensive extended tight-binding model (xTB) [4]. The success of the xTB approach will provide a cheaper option to study fullerene-based larger systems. [1] M. Madjet et al., Phys. Rev. Lett. 126, 183002, (2021); [2] A V. Akimov and O.V Prezhdo, J. Chem. Theory Comput. 9, 11 (2013); [3] J. Kang and L.-W. Wang, Phys. Rev. B 99, 224303 (2019); [4] C. Bannwarth et al., Comp. Mol. Sc. 11, 1493 (2021). |
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V01.00121: Mass-selected Ion-molecule Cluster Beam Apparatus for Ultrafast Photofragmentation Studies Xiaojun Wang, Mahmudul Hasan, Yibo Wang, Lin Fan, Daniel S Slaughter, Martin Centurion We describe an apparatus to study the fragmentation of iodide-molecule clusters triggered by laser excitation and transfer of an electron from the iodide to the neutral molecule. The instrument captures both charged and neutral fragments. The apparatus comprises a source to generate the ion-molecule clusters, a time-of-flight (TOF) spectrometer and a mass filter to select the desired anions, and a detection chamber where the laser excites the clusters and the fragment anions and neutrals are captured. The apparatus performance is tested by measuring the photofragments: I-, CF3I- and neutrals from photoexcitation of ion-molecule cluster CF3I·I- using 266 nm UV laser.The experimental results are compared with recent experiments and calculations, with particular attention to the dynamics of the photoexcitation. |
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V01.00122: Development of a soft-x-ray attosecond transient absorption spectroscopy system with a mid-infrared laser driver Michael McDonnell, Islam S Shalaby, Nisnat Chakraborty, Dipayan Biswas, James K Wood, Brandon Friend, Colin Murphy, Arvinder S Sandhu We will present the capabilities of a new soft-x-ray transient absorption spectroscopy system developed in our lab. The soft-x-ray generation occurs through high harmonic generation process, pumped by various MIR laser pulses. First, we used 1 micron wavelength driver followed by a hollow core fiber and chirped mirrors to produce broadband IR pulse that generates attosecond x-ray pulses in the range from 10-100 eV. Our second approach relies on the application of an OPCPA with tunable laser pulses from 1.5 to 3.4 micron, which provides access to 100-600 eV x-rays. An angular streaking detector characterizes the x-ray pulse duration. The transient absorption spectrometer forms the main diagnostic technique to be used for experiments geared to monitor the charge migration in molecules. We will present the first results obtained from using this system. |
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V01.00123: Theoretical study of the effects of autoionizing resonances in XUV pump – IR probe photoelectron spectrum of N2 Hung V Hoang, Pengju Zhang, Hans Jakob Wörner, Anh-Thu Le We provide detailed theoretical investigation of the effects of autoionizing resonances on XUV pump -- IR probe photoelectron spectrum of N2 by solving the coupled-channel time-dependent Schrodinger equation for coupled electron-nuclear dynamics. N2 is first excited by ~14.15 eV extreme-ultraviolet (XUV) photons to valence b’1Σu+ state. It is then probed by the absorption of two or three near-infrared (NIR) photons (800 nm). The coherent superposition of the wave packet on the valence b’1Σu+ state manifests in the beat frequency of the photoelectron spectrum of N2+. Our simulations agree well with the experimental data. In addition, two autoionizing Rydberg states converging to the excited A2Πu and B2Σu N2+ cores are accessed by the resonant absorption of NIR photons via phases and amplitudes of the oscillations of the photoelectron spectrum. This work shows the capability of time-resolved photoelectron spectroscopy as a powerful tool for characterizing the properties of such resonances. |
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V01.00124: Ultrafast relaxation of photoexcited C60: a comparison among DFT models Ruma De, Esam Ali, Mohamed El-Amine Madjet, Himadri Chakraborty Studies of the relaxation dynamics of photoexcited electrons in fullerene materials have applications in organic photovoltaics and medical photothermal therapy. In this work, we use an approach of electron-phonon coupled nonadiabatic molecular dynamics [1], based on density functional theory (DFT) [2-3], to simulate such relaxation process in C60. The methodology relies on a combination of the fewest-switch surface hopping approach and Kohn−Sham single-particle description [2]. We calculate the femtosecond evolution of the population of initial excited states and of various intermediate states. A comparison of results obtained using the PBE, PBE0, and B3LYP exchange-correlation functional, will be presented. The population lifetimes are found to reflect the structure of unoccupied band which may inspire experiments in laser two-photon schemes. [1] M. Madjet et al., Phys. Rev. Lett. 126, 183002, (2021); [2] A V. Akimov and O.V Prezhdo, J. Chem. Theory Comput. 9, 11 (2013); [3] M. Madjet et al. J. Phys. Chem. Lett 8, 18 (2017). |
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V01.00125: Two-photon excitations of the water molecule studied by time-resolved ion momentum spectroscopy John Searles, Anbu S Venkatachalam, Zane D Phelps, Huynh Van Sa V Lam, Itzik Ben-Itzhak, Daniel Rolles, Artem Rudenko, Eric Wells, Herschel A Rabitz, Artur F Izmaylov, Jacob Levitt Photoexcitation and photodissociation dynamics of the water molecule have been extensively studied both experimentally and theoretically, strongly motivated by atmospheric and biological importance of this system. While most of these studies focused on the dynamics induced by a single vacuum-ultraviolet photon, the same range of excited states can be populated by two-photon absorption. Since the latter process can be efficiently driven by wavelength-tunable femtosecond ultraviolet (UV) sources, it significantly facilitates time-domain measurements. In this work, we explore the dynamics induced by two-photon excitation of water in a femtosecond UV pump / near-infrared (NIR) probe experiment. Here, the NIR probe pulse ionizes the UV-excited neutral molecule, and the time evolution of the system is mapped by measuring the yields and kinetic energy distributions of the resulting ionic fragments as a function of UV-NIR delay. We analyze the wavelength dependence of two-photon excitations in 240-250 nm range and compare the results for H2O and D2O molecules. |
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V01.00126: Imaging rehybridization dynamics into the pericyclic minimum of an electrocyclic reaction in real-time Yusong Liu, David M Sanchez, Jie Yang, Martin Centurion, Pedro Nunes, Todd J Martinez, Thomas J Wolf We investigate structural dynamics of wavepacket relaxation along pericyclic transition states with a combination of ultrafast electron diffraction (UED) and ab-initio multiple spawning (AIMS) simulation. We focused this study on alpha-terpinene (αTP, C10H16), which is a derivative of 1,3-Cyclohexidiene (CHD, C6H8) by the addition of two substituents, a methyl group and an isopropyl group (replacing the relevant hydrogen atoms). We took the advantage that αTP does not qualitatively alter the photochemical dynamics in comparison of CHD, but the carbons in the substituent groups act as “reporter” atoms in adding signatures of carbon-carbon bond distance to the time-dependent pair distribution functions (PDFs), which were missing in our previous study of CHD. We observed real-time signatures of the structural evolution towards the pericyclic minimum in both measurements and simulations. Detailed analyses from the simulated wavepacket revealed the signatures to be due to the hybridization change from sp3 to sp2 configurations largely happening in the excited state prior to bond dissociation to the ring-opening which takes place directly after the internal conversion to the ground state. Our combined experimental and theoretical approaches highlighted the real-time structural dynamics leading to overlap of the conjugated π-system with the σ-bond prior to its dissociation. |
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V01.00127: Photofragmentation of CD3+ driven by intense ultrashort laser pulses* Naoki Iwamoto, Chandan Bagdia, Travis Severt, Tiana A Townsend, Kevin D Carnes, ITZHAK BENITZHAK We investigate photofragmentation processes of CD3+ by focusing intense ultrashort laser pulses‡ onto a fast (keV) CD3+ ion beam target. The use of an ion beam as a target allows for the direct position-and-time measurement of all ionic and neutral fragments, which we then use to calculate their 3-D momenta. Comparing the relative probabilities (branching ratios) of different photodissociation and photoionization processes is one of our main goals. However, contributions from a contaminant ion beam must be determined and subtracted. Also, the kinetic energy release (KER) and angular distributions of these processes are determined. It is worth noting that dissociation of CD32+ involves both charge-symmetric (CD2+ + D+), i.e., deprotonation, and charge-asymmetric dissociation (CD22+ + D), i.e., hydrogen elimination. |
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V01.00128: Fragmentation of CD4+ induced by intense ultrashort laser pulses* Chandan Bagdia, Naoki Iwamoto, Travis Severt, Kevin D Carnes, ITZHAK BENITZHAK The fragmentation of CD4+ molecular ions is investigated by focusing intense ultrashort laser pulses‡ onto fast (keV) CD4+ ion beam targets. A coincidence three-dimensional momentum imaging technique allows us to measure the laser induced charged and neutral fragments. One of our goals is to study the competition between different CD4+ dissociation processes, specifically hydrogen elimination (CD3+ + D), deprotonation (CD3 + D+), and the hydrogen-molecule elimination (CD2+ + D2). In addition, we observe a very weak molecular hydrogen ion elimination (CD4+ → CD2 + D2+). Curiously, some branching ratios show strong wavelength dependences. We will also discuss the kinetic energy release (KER) and angular distributions of these breakup processes, as well as other two- and three-body breakup channels following the ionization of CD4+. |
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V01.00129: Time-resolved Coulomb explosion imaging of UV-excited diiodomethane Anbu S Venkatachalam, Huynh Van Sa Lam, Artem Rudenko, Daniel Rolles The dynamics in halogenated methanes after UV excitation are of significant interest in the study of light-induced dynamics in gas-phase molecules. Upon UV excitation, diiodomethane (CH2I2) can follow multiple pathways resulting in direct C-I bond cleavage and fragment rotation, isomerization, molecular iodine formation, etc.,. We employ time-resolved strong-field Coulomb explosion imaging to directly probe the different pathways. UV light at different wavelengths produced by an optical parametric amplifier (OPA) excites the gas-phase CH2I2 molecules, which are probed by a strong ultrafast near-infrared (NIR) pulse. The resulting ions are detected in coincidence using a velocity map imaging spectrometer. Contributions of the different pathways and end products are inferred from the delay-dependent KER spectra, angular distributions, and energy sharing between different ionic fragments. |
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V01.00130: Using High Harmonic Generation Spectra to Study Returning Electronic Wavepackets Exposed to a Strong Laser Field Pavan N Muddukrishna, Abraham C Garibay, Eric Mullins, Sajed Hosseini-Zavareh, Kenneth J Schafer, Louis F DiMauro, Cosmin Blaga When an atom or molecule is exposed to a strong laser field, ionization occurs via absorption of one or more photons. Once ionized, the electron, caught in an oscillating field, may be driven back to the ionic core and either recombine with the parent ion, elastically re-scatter off it, or inelastically re-scatter. This elastic re-scattering phenomena has lead to the observation of an enhancement within the Above Threshold Ionization (ATI) spectra of noble gases at very specific field intensities along the laser polarization. Many theories have been provided over the last three decades, but the cause of this enhancement is still not very well understood. Understanding the behavior of the evolving electronic wavepacket within the recombination channel could provide key insights to the development of the enhancement. Here, we present a time-energy Fourier analysis of calculated High Harmonic Generation (HHG) spectra. We show clear cycle to cycle HHG yield increases at specific laser intensities. |
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V01.00131: Distinguishing Molecular Structures using Laser-induced Coulomb Explosion Imaging Huynh Van Sa V Lam, Anbu S Venkatachalam, Surjendu Bhattacharyya, Keyu Chen, Vinod Kumarappan, Artem Rudenko, Daniel Rolles Recently, Coulomb explosion imaging (CEI) with both XFELs and near-infrared (NIR) femtosecond lasers was shown to be a powerful method to obtain detailed structural information of gas-phase molecules with ten or more atoms. This suggests that time-resolved CEI could be used to follow the structural dynamics of molecules in chemical reactions such as ring opening. A ring-opening reaction can lead to a variety of final products, some of which are non-planar and have low symmetry (e.g., chain structures and smaller rings with higher ring strain). In this work, we investigate the static CEI patterns of a series of molecules that resemble the structures of "open-ring" and "closed-ring" products formed in a UV-induced ring-opening reaction. These patterns can be used as reference images to help identify the photoproducts in time-resolved CEI experiments. The experimental data are compared with CEI patterns produced from classical Coulomb explosion simulations to shed light on different aspects of the problem and to discuss the potential of distinguishing different products in ring-opening reactions using this method. |
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V01.00132: Angular Streaking of Auger-Meitner Electrons from Partially Coherent Photoions Jun Wang, Philip H Bucksbaum, Taran Driver, Agostino Marinelli, James P Cryan Ultrafast x-ray pulses can ionize molecules into partially entangled pairs of photoelectrons and core-excited ions, especially when the electron wavepackets from different continua overlap. The subsequent Auger-Meitner (AM) emission from the partially coherent cation is investigated with the angular streaking technique. An additional circularly polarized infrared laser pulse allows us to measure the temporal profile of the AM decay which characterizes the coherence of the intermediate cation. We present a model for angular streaking of this AM decay, where different intermediate electron/photoion pairs interfere in the same final dication state. Within the strong field approximation, a two-continuum model is employed and the resulting modulation of the AM current is shown. Correlation between the photo- and AM electrons is manifested by modeling of the two-electron joint momentum distribution. This provides a framework for the description of probing coherent electronic properties in molecules using angular streaking. |
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V01.00133: TRPES Investigation of Methylated Cyclopentadiene with UV Pump and XUV Probe Zane D Phelps, Lisa Huang, Tristan Fehl, Dennis Meyer, Fabiano Lever, Stefan Duesterer, Artem Rudenko, Martin Centurion, Adam Kirrander, Peter M Weber, Markus Guehr, Daniel Rolles We have applied time-resolved photoelectron spectroscopy (TRPES) using two UV-pump wavelengths (266 nm and 252 nm) along with a 30-eV XUV probe to study the ultrafast dynamics and possible ring conversion of methylated cyclopentadiene (CPD). Using an XUV pulse as the probe provides access to the molecular dynamics beyond the Frank-Condon region. Our preliminary analysis shows different de-excitation timescales for tetramethyl-CPD and pentamethyl-CPD as well as a dependence on the excitation wavelength. |
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V01.00134: high-resolution x-ray stimulated Raman spectroscopy using stochastic pulses kai li, Linda Young, Alexander Magunia, Christian Ott, Gilles Doumy, Thomas Pfeifer, Rubensson Jan-Erik, Michael Meyer, Tommaso Mazza, Marc Rebholz The X-ray free-electron lasers (XFELs) generate high-intensity x-ray pulses, which enable x-ray nonlinear spectroscopies. The extension of nonlinear spectroscopies to the x-ray domain promises the observation of electronic dynamics in their natural timescale with atomic spatial resolution. Stimulated x-ray Raman spectroscopy is an especially powerful tool, which works in a propagation mode and combines large signal enhancement through stimulated emission with ultrahigh energy resolution that overcomes the core-hole lifetime broadening. We present high-resolution stimulated Raman spectroscopy realized using stochastic XFEL pulses and correlation techniques. A covariance map between the transmitted incident SASE pulse and the stimulated Raman scattering produces a high-resolution x-ray Raman spectrum. This promising tool could be applied to study ultrafast electronic and molecular dynamics such as charge transfer in complex systems. |
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V01.00135: Time-Resolved Dynamics on the Giant Plasmon Resonance of C60 Debadarshini Mishra, Aaron C LaForge, Razib Obaid, Shashank Pathak, Florian Trost, Hannes Lindenblatt We will present the time-resolved ionization and fragmentation dynamics of C60 using intense, ultrashort radiation from the FLASH free-electron laser tuned above, on, and below the giant plasmon resonance around 20 eV. The ion dynamics were probed using a one-color XUV pump-probe technique in combination with a reaction microscope. We performed a systematic study of the time-dependent kinetic energies of the atomic and molecular ionic fragments as a function of photon energy and pulse intensity. Comparison with simulations for C+ and C2+ reveal that their measured kinetic energy distributions are characteristic of neutral fragments, i.e., C and C2. This suggests that our experiment provides information on the dynamics of neutral light fragments which typically remain unobserved. |
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V01.00136: Attosecond Science at the Linac Coherent Light Source James P Cryan The study of ultrafast electronic phenomena requires light pulses that can access the timscale of electronic motion, which typically in the range of few- to sub-femtosecond. Free Electron Lasers (FELs), are a powerful source of short wavelength radiation, which is useful for probing quantum systems with atomic site-specificity. With recent technical developments, FELs are now able to produce pulses with durations reaching below one femtosecond. I will present the recent scientific developments achieved using the Linac Coherent Light Source (LCLS) to probe electronic motion on this extreme timescale. This includes pump/probe spectroscopy, X-ray wave mixing, and streaking experiments making use of an additional laser field. |
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V01.00137: Time-Domain Ghost Imaging for Improved Laser/X-ray Pump-Probe Temporal Resolution Kurtis D Borne, Felix Allum, Xinxin Cheng, Ruaridh Forbes, James M Glownia, Martin Graßl, Alice Green, Andrei Kamalov, Xiang Li, Ming Fu Lin, Yusong Liu, Razib Obaid, Adam M Summers, Jun Wang, Daniel Rolles, Thomas Wolf, James P Cryan, Taran Driver We demonstrate the application of time-domain ghost imaging to improve temporal resolution in laser/x-ray pump-probe experiments conducted at free-electron lasers (FELs). In the case where a 'slow' detector, is used to record the data, the time-resolution of traditional pump-probe measurements is limited by laser/x-ray timing jitter in the detector integration window. In this context, ‘slow’ refers to detectors that are unable to readout at the full repetition rate of the FEL, and thus average over multiple FEL pulses, such is the case for large area detectors at next generation FEL facilities. We demonstrate that by correlating single-shot measurements of the laser/x-ray timing (e.g. using an x-ray/laser cross-correlator) with averaged detector values, we can reconstruct the time-dependent signal from optical-pump -- XFEL-probe measurements with temporal resolution that is no longer limited by the laser/x-ray timing jitter. Our method is especially relevant for the next generation of high repetition rate FELS. An exemplary case for time-resolved near-edge x-ray absorption spectroscopy is shown, and further applications are discussed. |
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V01.00138: Theoretical Calculations of the Resonant Double Core-Excitation and Autoionization Decay of N2 Adam E Fouda, Gilbert Grell, Sergey I Bokarev, Phay J Ho, Eetu Pelimanni, Linda Young, James P Cryan, Iyas Ismail, Dimitris Koulentianos, Tommaso Mazza, Michael Meyer, Maria Novella N Piancastelli, Ralph Püttner, Marc Simon, Gilles Doumy Here we present theoretical calculations supporting the experimental observation of a molecular resonant double-core excitation process in N2. This process was driven by a single few femtosecond soft X-ray Free Electron Laser (XFEL) pulse sequentially that excites two core level electrons to the same unoccupied molecular orbital. Multiconfigurational electronic structure calculations of X-ray absorption near-edge structure show a photon energy tuned to the 1sσ → 1π*g resonance requires a minimum bandwidth around 2 eV to drive the double core-excitation and that the second core-excitation energy is lowered in energy with respect to the ground state value. High-level Auger-decay calculations of the single and double core-excited states, explicitly considering the wavefunction of the ejected electron, validate the signatures of the formation and decay of neutral two-site double core hole states are observed in the experiment. The excitation process should be general, enabling the production of exotic neutral multi-core hole states with high site- and orbital-selectivity, providing a resonant X-ray pump/probe scheme and being of general interest for XFEL measurements performed in resonant conditions. |
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V01.00139: Electric field-resolved nonlinear optical measurements in hexagonal boron nitride Yuyan Zhong, Francis F Walz, Siddhant Pandey, Sumukh Vaidya, Xingyu Gao, Tongcang Li, Niranjan Shivaram We present measurements of the femtosecond electric field emitted from a third-order nonlinear optical interaction in hexagonal boron nitride (hBN). Using a sensitive interferometric technique known as TADPOLE, we measure the complete femtosecond electric field of the weak nonlinear signal generated using a degenerate four wave mixing (DFWM) scheme. In this scheme, three femtosecond pulses of the same wavelength (800 nm) interact with free-standing multi-layer hBN mounted on a 200-micron diameter aperture from which a nonlinear signal pulse is emitted. Two of the pulses are time delayed with respect to the third which allows us to extract dynamical information about the nonlinear interaction. The measurement of the temporal phase of the emitted signal electric field offers detailed information not available in typical nonlinear optical measurements. |
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V01.00140: Optical control of the XUV absorption spectra for spin-orbit states in Argon ion Nisnat Chakraborty, Islam S Shalaby, Michael McDonnell, Sergio Yanez-Pagans, Dipayan Biswas, James K Wood, Arvinder S Sandhu The coherent evolution of the electron-hole evolution in ionic systems is of high interest in attosecond community. We conducted multi-pulse attosecond transient absorption spectroscopy to study the impact of laser dressing on the evolution of the transition dipole in Argon ion. Ionic states are prepared using a multi-photon ionization by the infrared (IR) pump pulse, which are subsequently excited with a delayed extreme ultraviolet (XUV) pulse, leading to transitions from the two spin-orbit split ionization thresholds to the doublet of 4d spin-orbit split states around 23.85 eV. The transient XUV photoabsorption spectra show 100fs quantum beats around the region where the XUV and the ionizing beam overlap temporally. To study the role of laser fields in time-dependent evolution of the transition dipole, we use a second dressing IR pulse, which is two orders of magnitude weaker in intensity than the pump IR pulse. The dressing pulse is fixed in delay and arrives 250 fs after the pump pulse. We observe that two main absorption lines between lowest ionic states and 4d doublet merge into one and split again, thereafter splits again into two as the action of dressing IR pulse ceases, hence demonstrating an efficient ultrafast optical switching technique with moderately strong laser fields. |
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V01.00141: Theoretical study of two photon ionization of atomic argon in pump-probe spectrometry. Miguel Alarcon, Chris H Greene, Alexander C Plunkett, James K Wood, Dipayan Biswas, Arvinder S Sandhu In an experimental poster presented in parallel to this theoretical study, an exploration of two-photon ionization using pump-probe spectroscopy in atomic argon exhibits oscillations with the time delay of the probe. These experimental observations show two relevant features. First, there is a significant phase difference between the signal corresponding to the ionization leaving the core on each spin-orbit split state. Second, the angular distribution of the electrons has a higher degree of asymmetry than what a two-photon process would suggest. We propose a theoretical model based on multichannel quantum defect theory that describes this process. We used MQDT to incorporate the full complexity of the bound states involved in the process in the calculation. Since the process is outside the limits of perturbation theory, we perform time propagation of the quantum state on a Hilbert space composed of the most relevant states of the atom based on the bandwidth of the two pulses. By exploiting the linearity of the Schrödinger equation, we managed to obtain an efficient way of generating the observed spectrograms achieving a high degree of match between the predicted signal and the experimental observation. We replicate the relative yield of ionization between each ionic state and the phase difference between the two peaks. To describe the high degree of asymmetry we included the atomic states required to sustain four-photon processes. These processes seem to be strongly driven due to the strong coupling of nearly resonant transitions, but the theory underestimates the effects, yielding a lower degree of asymmetry. Further study is required to determine the driving force behind this feature. |
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V01.00142: Time-resolved Coulomb Explosion Imaging of the Ultrafast Ring-opening Reaction of Furan Enliang Wang, Surjendu Bhattacharyya, Keyu Chen, Kurtis D Borne, Farzaneh Ziaee, Shashank Pathak, Xiangjun Chen, Rebecca Boll, Till Jahnke, Daniel Rolles, Artem Rudenko The ultrafast molecular dynamics of gas-phase furan were investigated by time-resolved Coulomb explosion imaging (CEI). The ultrafast nonadiabatic transitions leading to ring opening were initiated by ultraviolet (200 nm) excitation. The transient molecular geometries were probed by CEI induced by near-infrared laser pulses and visualized as Newton plots. These Newton plots displayed clearly changing structures as a function of pump-probe delay. Molecular dynamics simulations revealed that the ring-opening reaction led to an isomer with a carbon-chain structure that is responsible for the observed changes in the Newton plot. |
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V01.00143: Cavity-enhanced transient absorption spectroscopy of 2-thiouracil Rudolf Popper, Myles C Silfies, Susanne Ullrich, Thomas K Allison The ultrafast dynamics of 2-thiouracil after excitation by UV light, and their comparison to those of uracil, have garnered significant interest recently in the context of understanding the photostability of nucleobases. However, previous gas-phase time-resolved photoelectron spectroscopy (TRPES) and solution-phase transient absorption spectroscopy (TAS) experiments have reported very different excited-state dynamics [1]. The competition between relaxation pathways involving internal conversion and intersystem crossing impedes theoretical treatments of 2-thiouracil. TAS is an excellent probe for studying intersystem crossing due to the unique spectral profiles of the triplet states, but previous TAS studies have been restricted to the solvated molecule. |
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V01.00144: Observing Early Ultrafast Dynamics in the Strong-Field Ionization of Liquid Water Aaron M Ghrist, Mathew Britton, Ruaridh Forbes, Andrew J Howard, David J Hoffman, Jake D Koralek, Philip H Bucksbaum Ionization from strong-field light is a well-established tool for studying the ultrafast dynamics of molecules, but so far has been largely dominated by gas-phase studies. Field-ionization in solution-phase systems follows the same physical principle of a binding potential being distorted to form a free electron, which can either recombine with the ionized molecule or cluster as in high-harmonic generation, or be sufficiently separated from the ion to remain unbounded. In a dipolar medium such as liquid water, these unbounded electrons form solvated electrons that on the picosecond timescale exhibit polaron oscillations, but the mechanism for the femtosecond (fs) behavior of these systems is not well understood. In particular, the underlying molecular physics of the initial charge formation below 100-fs have been experimentally elusive due to a lack of sufficient time resolution. Here we present a table-top study of the radiolysis of water that emphasizes these ultrafast dynamics. |
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V01.00145: Photoelectron and transient absorption spectroscopy on molecular Rydberg states of carbon dioxide Dipayan Biswas, James K Wood, Alexander C Plunkett, Sergio Yanez-Pagans, Islam S Shalaby, Arvinder S Sandhu We have used time-resolved differential pump-probe photoelectron spectroscopy to study the competition between autoionization and predissociation dynamics in the Rydberg states of carbon dioxide. An attosecond XUV pulse excites the ground state of the molecule to two overlapping neutral Rydberg series, namely Tanaka-Ogawa and Henning series, converging to A and B continua, respectively. These states, if unperturbed, can undergo spontaneous autoionization and predissociation, where the former depends on the principal quantum number and later depends on the vibrational states and curve crossings. The presence of a conical intersection between these two series makes this system very interesting for the investigation of non-adiabatic dynamics. In our experiment, a time-delayed near infrared probe pulse ionizes the Rydberg states and we study the energy and angular distribution of the photoelectrons emitted. We observe a discrepancy between the photoelectron spectra and the results from transient absorption spectroscopy, as the photoelectron spectra do not contain the expected contributions from the Henning series. We extract previously unknown autoionization and dissociation lifetimes of the Tanaka-Ogawa Rydberg states. These lifetimes show interesting behavior with variation of the probe intensity and frequency which indicates light-induced effects alter the electron dynamics. |
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V01.00146: STRUCTURE AND PROPERTIES OF ATOMS, IONS, AND MOLECULES
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V01.00147: The Role of an Atom in the Expansion of the Universe Hassan Gholibeigian, Zeinab Gholibeigian Every fundamental particle involved in an atom contains an information quantum potential (IQP) that receives its necessary information and processes it to use the result (consciousness) for its next dynamic motion. An atom, like a human and everything else, consists of two quantum fields corresponding to two different boundary surfaces. The first quantum field consists of the fundamental particles of the atomic body. Quantum states (qubits) of the involved elementary particles changes/increase as they communicate with each other. The second quantum field contains the IQPs of the fundamental particles of the atom as a hologram, which we propose as the quantum mind/psyche/soul of the atom. The boundary surface of the hologram is not physical, but an imaginary mathematical shell. Each quantum state of the fundamental particles involved in the hologram is placed as a code on its surface within a Planck plane. Parallel to this coding, the coded information and concepts are transferred to the edge of the universe and coded on the hologram of the universe. Therefore, the hologram of the universe is continuously expanding as the boundary surfaces of all the holograms of atoms increase, parallel to the expansion of the universe by dark energy. |
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V01.00148: ULTRAFAST AND STRONG FIELD PHYSICS
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V01.00149: Excited atoms density buildup in long-wavelength filamentation in atmospheric pressure gases* Suyash Bajpai, Dmitri A Romanov, Robert J Levis When free electrons are driven by the strong oscillating electric field of a femtosecond laser pulse, the amplitude of their oscillations (the ponderomotive radius) scales as the square of the laser carrier wavelengths. For a long-wavelength (~4 microns) laser pulse interacting with a gas at atmospheric pressure, the ponderomotive radius is comparable with the interatomic spacing. In this situation, the driven electrons collide effectively with the neighboring neutral atoms, and this allows the electrons to gain energy via inverse Bremsstrahlung on neighboring atoms. Moreover, these collisions can either ionize the neighbor atoms or promote them to an excited state, leading to a considerable build-up of the excited-atom density. Such a buildup of excited atoms leads to a number of transient optical effects in the wake of the laser pulse, especially to the hallmark effect of Rabi sideband generation. Addressing the case of atmospheric-pressure argon, we investigate the production of excited atoms and ions, as well as the control of these processes by the shape of the long-wavelength femtosecond laser pulse. We further obtain the characteristic patterns of Rabi sideband emission from the filament wake channels. |
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