Bulletin of the American Physical Society
53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 67, Number 7
Monday–Friday, May 30–June 3 2022; Orlando, Florida
Session N01: Poster Session II (4:00-6:00pm, EDT)Poster
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Room: Grand Ballroom C |
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N01.00001: ATOMIC, MOLECULAR, AND CHARGED PARTICLE COLLISIONS
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N01.00002: Progress on the Rubidium Spin Filter Karl J Ahrendsen, Ken Trantham, Dale Tupa, Timothy J Gay We report the most recent advances in the development of a novel source of spin-polarized electrons: the Rb Spin Filter [1]. Polarized electron beams are produced by driving an unpolarized beam of thermionically emitted electrons through a target cell containing a mixture of spin-polarized Rb vapor at 1/3 mTorr and N2 at 400 mTorr. The apparatus has been updated to incorporate a differential pumping region, as well as a target chamber for our continuing studies of asymmetries in the interaction between longitudinally spin-polarized electrons and chiral molecules[2]. Our improved system can regularly obtain electron polarizations between 15% and 25% at currents of up to 1 µA. We have collected preliminary data investigating the chiral asymmetry in secondary electron emission coefficients from both enantiomers of cysteine. |
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N01.00003: Theoretical study of the dissociative recombination and rovibrational excitation of CF+ in collisions with low-energy electrons Viatcheslav Kokoouline, MEHDI Ayouz, Joshua B Forer, Samantha Fonseca dos Santos, Ioan Schneider, Jeoffrey Boffelli, Oleksii Kulyk Preliminary results from the theoretical approach to model the dissociative recombination (DR) and ro-vibrational (de)excitation (R-(d)VE) of CF+ will be presented. The approach combines the MESA code (Molecular Electronic Structure Applications), the UK R-matrix method for fixed-nuclei electron-ion scattering, the vibronic frame transformation with outgoing-wave dissociative functions obtained using a complex absorbing potential and molecular quantum-defect theory. Comparison with previous calculation (from complex Kohn variational method and multichannel quantum defect theory) and experimental results (Test Storage Ring in Heidelberg) are shown. The study of CF+ is of relevance for astrochemistry and more specificly in diffuse interstellar media (ISM) as it regarded as a possible probe for molecular hydrogen column density. |
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N01.00004: Study of the dissociative resonances of NO2 in collisions with low-energy electrons Anthony Bonilha, MIKHAIL GUCHKOV, MEHDI Ayouz, Nicolas Douguet, Viatcheslav Kokoouline, Samantha Fonseca dos Santos We investigate the resonances leading to the dissociative electron attachment of NO2 using the complex Kohn variational method. In particular, we characterize and put in evidence the orbitals responsible for the fragmentation of NO2 as well as the resulting fragments angular distribution computed via the resonances amplitudes extracted from the S-matrix in the axial-recoil approximation. |
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N01.00005: Low-Energy Dissociative Recombination of CH+ Viatcheslav Kokoouline, MEHDI Ayouz, Joshua B Forer, Chris H Greene, Xianwu JIANG, Ioan Schneider Modelling the dissociative recombination (DR) of molecular ions becomes complicated when the direct and indirect DR mechanisms compete with each other. This typically occurs in ions with low-energy electronic resonances, e.g., open-shell molecular ions. We present a theoretical approach to model this process that combines three methods: (i) fixed-nuclei electron-ion scattering with the UK R-matrix method, (ii) rovibronic frame transformation with dissociative wave functions obtained with a complex absorbing potential, and (iii) molecular quantum-defect theory. We apply this approach to the CH+ ion. Past studies of the DR of CH+ have shown that the Rydberg series belonging to the two lowest excited states of the ion, a3Π and A1Π, and d-type partial waves of the incident electron have a significant impact on the DR cross section. We improve on our recent study of CH+, of which the results were only vibronically resolved, by performing a rovibronic frame transformation and present our rotationally resolved results compared against recent experimental data. |
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N01.00006: Double-differential cross section for single ionization of Fullerene by proton projectile Esam Ali, Ibrahim Hamammu, Hari Chaluvadi, Himadri Chakraborty, Chuangang Ning, Don H Madison We calculate 3DW-EIS (3 body distorted wave - Eikonal initial state) doubly differential cross sections (DDCS) for single ionization of the C60 fullerene by 75 KeV proton impact. The DDCS is differential in the ejected electron energy and the projectile scattering angle and integrated over the ejected electron angles. The purpose of our study is to look for resonances in outer shell ionization of fullerene and to investigate the importance of the interaction between the scattered proton with ejected electron on the DDCS resonance scattering as a function of ejected electron energy. |
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N01.00007: Triple differential cross section for THF electron-impact ionization Esam Ali, Ibrahim Hamammu, Jiaqi Zhou, Shaokui Jia, Xiaorui Xue, Himadri Chakraborty, Xueguang Ren, Alexander Dorn, Don H Madison We report a combined experimental and theoretical study of triple differential cross sections for intermediate-energy 250 eV electron-impact ionization of THF (C4H8O), for the highest occupied molecular orbitals (HOMO)[1-2]. The theoretical cross sections were calculated within a molecular 3-body distorted wave (M3DW) framework employing a proper orientation average and the results are compared with experiment for three different planes for the ejected electron, and in each plane, two different scattering angles of 6⁰ and 10⁰ and three different ejected electron energies of 10, 15, and 20 eV. We fully assess the ability of the theoretical model to reproduce the experimental data in terms of angular distribution and intensity. |
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N01.00008: Dynamics of dissociative electron attachment to model peptides Daniel S Slaughter, Guglielmo G Panelli, Ali Moradmand, Brandon J Griffin, Kyle J Swanson, Thorsten Weber, C W McCurdy, Dipayan Chakraborty, Sylwia Ptasinska, Thomas N Rescigno, Joshua B Williams Consider formamide, methylated formamides, and acetamide as prototypical molecules for the study of electron-capture-induced peptide bond breaking in protein or amino acid chains. The fundamental dynamics of dissociative electron attachment to simple amides is investigated by measuring the kinetic energy and angular distributions of anion fragments, using a momentum imaging reaction microscope. Transient anions are formed by electron attachment to molecules in an effusive beam, with a probability that is highly-dependent on the initial orientation of the target molecule[1]. In some cases, the experimental results reveal highly structured fragment angular distributions, offering direct insight into the symmetry of the resonances. At the lowest electron attachment energies in the experiments on formamide, the fragments dissociate with low kinetic energy, and the angular distributions have much broader structures[2]. These measurements are analyzed and informed by ab initio electron scattering calculations for two Feshbach resonances, indicating O-C-N opening dynamics for the lowest energy resonance. |
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N01.00009: COLD ATOMS, IONS, MOLECULES, AND PLASMAS
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N01.00010: Two Dimensional Synthetic Lattices of Laser-Coupled Atomic Momentum States Sai Naga Manoj Paladugu, Xiye Hu, Shraddha Agrawal, Bryce Gadway The one-dimensional Momentum Space Lattices (MSLs) offering spectroscopic control over lattice Hamiltonian terms have proven to be a versatile platform for studying lattice physics, quantum simulation, and topological materials. In this poster, I discuss our effort to implement the MSLs in two dimensions using a 39K Bose-Einstein Condensate. Comparing to our previous implementation of 1D MSLs using 87Rb BECs, the 39K BEC with its accessible magnetic Feshbach resonance will allow precise tuning of atomic interactions in the MSL. This 2D MSL will enable the engineering of exotic lattice structures and flat-band materials, as well as the exploration of new phenomena in topological, disordered, and frustrated systems. |
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N01.00011: From matter-wave quantum emitters to polariton physics in an optical lattice Alfonso Lanuza, Youngshin Kim, Joonhyuk Kwon, Hongyi Huang, Dominik Schneble We present an overview of our group's recent work with a flexible, well-controlled platform for studies of radiative phenomena with matter waves. Starting from experiments to observe spontaneous emission into vacuum [1], we have explored the decay of matter-wave quantum emitters coupled to a tunable analog of a photonic crystal [2]. A theoretical analysis including multiband effects in an array of emitters achieves very good agreement with the full set of our data and allows us to extract a polaritonic band structure [3]. We have recently probed the presence of such matter-wave quasi-particles and studied their transport and interaction properties [4] which provides opportunities for studies of exciton-polariton physics. |
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N01.00012: Quantum Computing with Circular Rydberg Atoms Yiyi Li, Sam R. Cohen, Jeff D Thompson Neutral-atoms in a optical tweezer arrays have become a leading platform for quantum computing and simulation. They combine attractive features such as large system size, long coherence time, and strong interactions. However, the fidelity of two-qubit gates based on interaction between Rydberg states is fundamentally limited by the finite lifetime of the laser-accessible low angular momentum Rydberg states. Circular Rydberg states with the maximal angular momentum (m=l-1) have longer lifetimes, but they are difficult to access from ground state due to the large momentum mismatch. To sidestep this challenge, we propose an alternative quantum computing approach by encoding qubits in different circular Rydberg states [1], building on a related proposal for quantum simulation [2]. |
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N01.00013: Towards Optical Lattice for 1D Ultracold Strontium Bose Gas Chuanyu Wang Development of a two-dimensional (2D) optical lattice to be used to create a 1D microtrap array for studies of 1D quantum gases is described. A 1064 nm fiber amplified laser system is used to create two orthogonal pairs of standing waves that together form a 2D lattice. By delivering 4W of power to each arm of the lattice and focusing the beams to a beam radius of ~300 microns at the location of the atoms, we can create a 2D lattice with a maximum trap depth around 70 photon recoils. This allows preparation of 1D atoms sample with a range of different average interaction energies thereby providing a rich yet simple system to study. Initial studies with our Rydberg molecule spectroscopy system will focus on probing the correlation function of 1D quantum gases with different interaction strengths. |
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N01.00014: Universal Kardar-Parisi-Zhang dynamics in integrable spin chains Bingtian Ye, Francisco Machado, Jack Kemp, Ross Hutson, Jun Ye, Norman Y Yao Recent advances in the control and manipulation of ultracold atoms in optical lattices have opened the door to studying SU(N)-symmetric spin models. This offers the tantalizing opportunity to study the dynamics of a wide variety of one dimensional integrable models where the interplay between integrability and symmetry leads to anomalous transport. Leveraging a novel numerical technique, termed density matrix truncation, we show that transport in these systems can be superdiffusive, and moreover fall into the Kardar–Parisi–Zhang (KPZ) universality class. This combines and generalizes previous theoretical and experimental results to SU(N) symmetric models, as well as to other non-Abelian symmetric models, their periodically driven counterparts, and supersymmetric analogues. By exploiting optical pumping, we discuss how to experimentally generate the spatially inhomogeneous, near infinite-temperature initial state required to study this novel KPZ transport. Moreover, we demonstrate how such transport can be identified from the spatial profile of polarization using current state-of-the-art single-shot detection with single-site spatial resolution. |
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N01.00015: P-wave Efimov physics creates a universal trimer in three fermion systems Yu-Hsin Chen, Chris H Greene Efimov physics at the p-wave unitary limit for three equal mass fermions interacting via Lennard-Jones potentials is predicted to modify the long-range interaction potential energy in multiple symmetries, but without producing a true Efimov effect. This analysis treats the orbital angular momenta and parities, $L^{\Pi} = 0^{+}, 1^{+}, 1^{-}, and 2^{-}$, for either three spin-polarized fermions or two spin-up and one spin-down fermion. Our results for the long-range interaction predicts that either one or two novel p-wave unitary channels emerge at unitarity, in multiple scenarios where the two-body p-wave scattering volume diverges for either a single-component or a two-component fermionic trimer. The new type of p-wave universal trimer can be formed in some specific symmetries i.e. $L^{\Pi} = 1^{+} or 1^{-}$. |
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N01.00016: Multichannel nature of Efimov physics with ultracold 7Li atoms Jose P D'Incao, Yaakov Yudkin, Paul S Julienne, Lev Khaykovich We present our current understanding of various aspects of Efimov physics originating from the complex multichannel hyperfine structure and overlap of Feshbach resonances for 7Li atoms. This further help us to explain puzzling experimental observations with ultracold gases. We have characterized the energies of Efimov states and corresponding interference and resonance scattering phenomena associated to them as a function of an external magnetic field. Our results also indicate that Efimov states in the 7Li system can have a unique mixed hyperfine character which strongly affect their near-threshold behavior for repulsive interatomic interactions. [1] Y. Yudkin, R. Elbaz, L. Khaykovich, arXiv:2004.02723. |
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N01.00017: Progress towards evaporation and sideband cooling of laser cooled CaF molecules Loic Anderegg, Sean Burchesky, Yicheng Bao, Scarlett Yu, Derick Gonzalez-Acevedo, Eunmi Chae, Kang-Kuen Ni, Wolfgang Ketterle, John M Doyle The wide-ranging scientific applications of ultracold molecules have inspired significant efforts in cooling and controlling molecules in the single quantum state level. Many potential applications are still hampered by the finite temperatures experimentally achieved. As temperatures are reduced further, motional decoherence rates are suppressed and fidelities increase, opening new opportunities for quantum simulations and computation. One of the most successful cooling methods for atomic species, evaporative cooling, requires a high elastic rate and large ratio of elastic to inelastic collisions. While this ratio is typically low for most molecules, using microwaves, we engineer a repulsive barrier between molecules, shielding inelastic loss and increasing the rate of elastic collisions. Using optically trapped CaF molecules, we demonstrate that the elastic rate can be increased while the inelastic loss is suppressed to reach a ratio of 50. By adiabatically lowering the trap depth to force evaporation of the hottest molecules, we were able to observe a drop in temperature of the sample when shielding was enabled compared to a control sample without shielding. Future improvements in initial density and number would allow for more effective evaporation.Evaporative cooling is useful for bulk samples, but to use molecules in single optical tweezer arrays requires single particle cooling. To this end we report progress towards sideband cooling of CaF molecules to the ground motional state of an optical tweezer. |
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N01.00018: Optical cycling of thallium fluoride Nathan Clayburn, Ikram Gabiyev, Olivier O Grasdijk, Jakob Kastelic, Oskari Timgren, David DeMille, Larry R Hunter Investigations of optical cycling of the B3Π1(ν′ = 0) ← X1Σ+(ν = 0) transition of thallium fluoride are reported. These investigations are motivated by the promise TlF holds for a measurement of the nuclear electric-dipole moment. With the goal of discovering a robust optical cycling scheme we measure UV fluorescence from the laser excitation of a cryogenic molecular beam and compare those results to theoretical predictions. A simple theoretical model which considers only rotational branching fails to agree with experiment as polarization and hyperfine dark states of the ground state are found to dramatically reduce photon cycling rates compared to those of a simple two-level system. More complete quantum mechanical trajectory simulations are reported which better capture the reality of the experiment and the effects of these dark states. |
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N01.00019: Towards Rearrangeable Tweezer Arrays of Laser-Cooled CaF Molecules Connor Holland, Yukai Lu, Lawrence W Cheuk Programmable arrays of polar molecules could be a powerful new platform to simulate lattice spin Hamiltonians and to explore quantum information processing with molecular qubits. In particular, rearrangeable optical tweezer arrays of laser-cooled molecules offer high detection fidelities and local control. In this poster, we present our recent progress towards realizing a rearrangeable optical tweezer array of laser-cooled CaF molecules. We describe several new techniques, including dynamical optical trap compression to enhance molecular densities, a method to characterize our high-resolution imaging system in-situ, and an imaging technique that offers nearly background-free detection with high fidelity. We also report on loading of single molecules into large 1D arrays and coherent rotational state control. |
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N01.00020: Improving molecule trap loading rate from a Cryogenic Buffer Gas Beam Thomas K Langin, Varun Jorapur, Qian Wang, Geoffrey Zheng, David DeMille Most experiments that employ direct laser cooling of molecules use cryogenic buffer gas beams (CBGBs) formed by ablating a precursor target in the presence of 4\,K helium. This provides a high flux of slow and rotationally cold molecules. Although CBGBs generate $\sim$ 10$^{12}$ molecules per ablation, only $\sim 10^{4}$ are typically captured in downstream magneto-optical traps (MOTs). Here we report numerical simulations of methods that promise to significantly increase the captured fraction of molecules. Our simulations show that transverse cooling, applied simultaneously with longitudinal slowing, can increase the capture fraction by a factor of 20 by reducing the molecular beam divergence. We also find that the shallow velocity cut-off in `white-light' slowing (a typical slowing scheme in molecule cooling experiments) causes a substantial number of molecules to never reach the MOT on account of being decelerated too quickly. We show that, by adding a 'push' beam co-propagating with the molecules, previously over-slowed molecules can be captured. Simulations indicate that combining these gains with improvements to the white-light slower could increase the capture fraction by a factor of $\gtrsim 100$. |
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N01.00021: Rovibrational optical cooling of Rb2 in a supersonic beam Manuel A Lefran Torres, David Rodriguez Fernandez, Marcos R Cardoso, Luis Gustavo Marcassa In this work, we propose to optically cool the rotation and the vibration of Rb2 molecules in a supersonic beam by applying a spectrally shaped broadband light source, which consists of several multimode diodes, in the range of 680 - 730 nm. Optical transitions from X1Σg+ ground state to the B1Πu excited potential can be driven by such source. The shaped spectrum is such that the X1Σg+(vx = 0, Jx = 0) and X1Σg+(vx = 0, Jx = 1) ground states will be a dark states. The molecules will be observed by photoionization technique, through transitions from the X1Σg+(vx, Jx) to B1Πu(vB, JB) potential using a CW diode laser, and then photoionized by a 532 nm pulsed laser. Such technique will allow us to resolve the rotational distribution of the X1Σg+(vx = 0). Theoretical simulations indicate that we should be able to perform the rovibrational cooling with this arrangement of lasers. |
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N01.00022: Ion-Rydberg molecules observed by a high-resolution ion microscope Robert Loew, Nicolas Zuber, Viraatt Anasuri, Moritz Berngruber, Yiquan Zou, Florian Meinert, Tilman Pfau Our ion microscope provides a highly tunable magnification, ranging from 200 to over 1500, a spatial resolution better than 200nm and a depth of field of more than 70µm. These properties and the excellent electric field compensation enable the observation of ion-Rydberg-interaction in cold bulk quantum gases [1]. |
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N01.00023: Site-resolved measurements of real and momentum space correlations of ultracold molecules in an optical lattice Ravin Raj, Lysander Christakis, Jason S Rosenberg, Sungjae Chi, Zoe Yan, Waseem S Bakr Ultracold molecules are prime candidates for the quantum simulation of many-body physics, owing to their long-range interactions and rich set of long-lived internal states. Here, we present our approach to prepare ultracold NaRb molecules from the Feshbach association of dual-species 2D condensates loaded into an optical lattice, before coherently transferring them to the molecular ground state via STIRAP. These are dissociated back into atoms and imaged using a quantum gas microscope for the site-resolved detection of the molecules. This enables us to probe multi-point correlations between the molecules that emerge due to either quantum statistics or interactions. We use this technique to make the first observation of the Hanbury Brown and Twiss effect with molecules by detecting their spatial bunching after a long-time of flight [1]. Additionally, starting from NaRb molecules in the absolute ground state, we excite microwave transitions to prepare superpositions with the first excited rotational molecular state, thereby turning on strong dipolar interactions. We measure long many-body limited rotational coherence times and use the microscope to study the dynamics of molecule pair correlations in the 2D quantum XY spin model. |
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N01.00024: Modeling laser cooling and molecular structure in BaF Marian Rockenhäuser, Felix Kogel, Ralf Albrecht, Einius Pultinevicius, Tim Langen Cold molecular gases are promising candidates for studies of cold chemistry, precision tests of fundamental symmetries and quantum simulation. Motivated by our experiments on barium monofluoride (BaF), we report here on the simulation of laser cooling for this species, using multi-level rate equations and optical Bloch equations. We present efficient Doppler, sub-Doppler and coherent cooling schemes for both bosonic and fermionic isotopologues of this species. In addition, we discuss the analysis of experimental spectra of the lowest vibrational transitions relevant for laser cooling of BaF. |
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N01.00025: Optical cavity for Rubidium molecule experiments David Rodriguez Fernandez, Manuel A Lefran Torres, Marcos R Cardoso, Luis Gustavo Marcassa We have constructed a medium finesse optical cavity for laser stabilization at 680 nm, which will be used for experiments involving rubidium molecules. The cavity is based on an ultra-low expansion glass spacer (ULE) placed inside a vacuum chamber, which is maintained at 10-7 Torr by a 2 l/s ionic pump. The spacer temperature is stabilized with a precision of 0.01 K by in vacuum TEC elements. Variable sidebands are created by using a computer-controlled radiofrequency synthesizer and an electro-optical modulator (EOM), which allow us to lock the laser to molecular transitions of interest by using the PDH technique. By performing iodine laser spectroscopy, we can determine the temperature for the minimum of the coefficient of temperature expansion. With this design, we expect to achieve a frequency drive of only 1 MHz per day, which will guarantee an improvement in the quality of our measurement at a relatively low cost. |
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N01.00026: Dipolar molecules finally truly under control! Andreas Schindewolf, Roman Bause, Xing-Yan Chen, Marcel Duda, Tijs Karman, Immanuel Bloch, Xin-Yu Luo Ultracold polar molecules offer strong electric dipole moments and a rich internal structure, which makes them ideal building blocks to explore exotic quantum matter, to implement novel quantum information schemes, or to test fundamental symmetries of nature. However, until recently, collisional loss at short range, even for nominally nonreactive molecules, has strongly limited the use of interacting molecules and prevented evaporation of the molecules to the quantum degenerate regime. We now demonstrate that coupling rotational states with a blue-detuned circularly polarized microwave can not only shield the molecules from reaching the lossy regime at short range, but simultaneously provides strong tunable dipolar interactions. We make use of this so called 'microwave shielding' to evaporate fermionic NaK molecules reaching a record low temperature of 21 nK, corresponding to 0.36 times the Fermi temperature. |
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N01.00027: Towards a Universal Optical Trap for Molecules Ashwin Singh, Lothar Maisenbacher, Jeremy Axelrod, Cristian D Panda, Holger Muller We propose a novel approach to optically trapping a wide class of chemical species at cryogenic temperatures, particularly small, closed-shell molecules. The trapping mechanism is insensitive to a molecule's internal state, energy level structure, permanent dipole moment, and magnetic properties. In this "universal" trap, molecules will be thermalized in a helium buffer gas at 1.5 K and trapped optically in a deep dipole trap operating at 1064 nm, which is far red-detuned from any molecular resonances. The ∼10 K trap depth will be produced by a tightly focused buildup cavity capable of reaching intensities of hundreds of GW/cm2 [1]. Here, we theoretically investigate the trapping and loading dynamics, as well as the one- and two-body loss rates, and conclude that, as a lower bound, molecules can be trapped for over a second at densities of order 1010 cm-3. We show that photo-ionization and photo-dissociation are negligibly small for a large number of candidate molecules. We also report on our progress towards experimentally demonstrating this novel trap. Our trap will open new possibilities in molecular spectroscopy, studies of cold chemical reactions, and precision measurement, amongst other fields of physics. |
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N01.00028: Optimization of Pulsed-Laser Ablation Production of Aluminum Monochloride for Laser Cooling and Trapping Chen Wang, Taylor Lewis, John R Daniel, Madhav Dhital, Chris Bardeen, Boerge Hemmerling Ultracold dipolar molecules provide opportunities for a variety of areas of fundamental research and novel technology, including precision measurements of fundamental constants, searching for new physics, such as the electron electric dipole moment, quantum simulation of many-body systems, quantum information processing and controlled chemical reactions. In recent years, magneto-optical trapping (MOT) of several species of molecules has been demonstrated. Ab-initio calculations and high resolution spectroscopy show that aluminum monochloride (AlCl) has highly diagonal Frank-Condon factors of 99.88%[1], which make it an excellent candidate for laser cooling and trapping. In addition to good photon scattering properties, it is paramount for any application to create high densities of the molecule of interest in the gas phase. |
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N01.00029: Towards a quantum simulator using ultracold dipolar NaCs molecules in a fully controlled electric field Yu Wang, Conner P Williams, Fang Fang, Jessie T Zhang, Lewis R Picard, Yichao Yu, Kang-Kuen Ni Polar molecules trapped in a 3D optical lattice assembled by optical tweezer arrays offer a compelling path towards quantum simulation due to the intrinsic field-tunable interactions and rich internal degrees of freedom of ultracold polar molecules. The dipolar interaction between molecules is long-range and of the order kHz in optical lattices, and can be controlled through DC electric fields and AC microwave fields. Building upon our first-generation molecular assembly experiment, which demonstrated the ability to fully control the rovibrational and hyperfine degrees of freedom of the molecule, we are constructing a new-generation setup to extend the molecular assembly to a much larger array with longer coherence times. We will implement an in-vacuum electrode system, capable of providing the large, stable, and homogeneous electric fields necessary to control the interactions, while also allowing high-resolution optical detection and addressing. We have designed an eight-rod electrode system in a squeezed octagon configuration based on finite-element simulation. Tests with a stable high voltage source will be performed to demonstrate that this electrode system can fully saturate the dipole moment of NaCs molecules while satisfying our homogeneity requirements. These ingredients enable a powerful quantum simulation architecture for the emulation of quantum magnetism. |
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N01.00030: Towards Microwave Shielding of NaCs Ground State Molecules Claire Warner, Niccolò Bigagli, Aden Z Lam, Weijun Yuan, Siwei Zhang, Ian C Stevenson, Sebastian Will We report on microwave studies of ultracold ground state sodium-cesium (NaCs) molecules. We show spectroscopic data on microwave transitions to the first rotationally excited state and model our system with a Hamiltonian that allows us to assign quantum numbers and transition strengths. We observe fast Rabi oscillations between the ground and first rotationally excited states. We are working towards strong coupling with circularly polarized microwave radiation to enable microwave shielding against two-body losses. For NaCs, this may allow direct evaporation to a molecular Bose-Einstein condensate. |
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N01.00031: Low-Phase-Noise High-Power Diode Laser Systems for the STIRAP transfer of Ultracold 6Li40K Molecules Anbang Yang, Xiaoyu Nie, Victor A Avalos Pinilos, Canming He, Sunil Kumar, Sofia Botsi, Kai Dieckmann 6Li40K molecules in their rovibrational ground state possess a relatively large permanent electric dipole moment of 3.6 Debye, which makes them good candidates for studying quantum many-body physics and quantum chemistry. Two sub-kHz linewidth external cavity diode laser (ECDL) systems have been built to transfer weakly-bound 6Li40K molecules to their ground state using Stimulated Raman Adiabatic Passage (STIRAP). Excessive residual laser phase-noise and scattering from unwanted intermediate levels have been identified as the two major contributions for the low transfer efficiency in our experiment. The cavity length of the ECDLs are extended from 3 cm to 20 cm to narrow the free-running laser linewidth. This leads to a reduction of integrated phase-noise from 200 mrad to 48 mrad in 10 MHz bandwidth. To suppress the scattering from unwanted states, a large single-photon detuning should be used in upcoming experiments. Tapered amplifiers have been integrated in the ECDL systems for achieving higher Rabi frequencies while preserving the low phase-noise of the long-cavity ECDLs. |
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N01.00032: Optical tweezer array of fully quantum-state-controlled polar molecules Jessie T Zhang, Lewis R Picard, Gabriel E Patenotte, Conner P Williams, Kenneth Wang, Kang-Kuen Ni Ultracold polar molecules, compared to their atomic counterparts, possess rich internal structures and exhibit long-range dipole-dipole interactions that render them useful for many applications such as quantum simulation of matter, quantum computation and precision measurements. At the heart of many of these proposals is the ability to trap and control ultracold molecules at the individual particle level. Recently, we have demonstrated this capability, assembling single rovibrational ground state NaCs molecules in optical tweezers starting from single ultracold atoms. This bottom-up approach utilizes laser cooling and trapping techniques of ultracold atoms and has enabled us to achieve full quantum state control, including all the internal and external degrees of freedom, on individually trapped molecules in an array. Furthermore, we have characterized the rotational transition of the ground state molecules, which is important for many exciting possibilities that can harness the rich properties of ultracold molecules. |
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N01.00033: Two-Photon Pathway to NaCs Ground State Molecules Siwei Zhang, Niccolò Bigagli, Aden Z Lam, Claire Warner, Weijun Yuan, Ian C Stevenson, Sebastian Will We report on the creation of an ultracold ensemble of ground state sodium-cesium (NaCs) molecules. To identify intermediate states suitable for stimulated Raman adiabatic passage (STIRAP), we study bound-to-bound transitions starting from Feshbach molecules [1]. Continuously covering a spectrum of 14 THz, we group lines based on internal structure and observe lines with exceptionally large linewidths greater than 1 GHz. We assign quantum numbers to these intermediate states. We perform detailed one- and two-photon studies on the B1Π and c3Σ+ lines and identify a bridge to the X1Σ+ ground state. Using this pathway, we observe 70% transfer efficiency to the rovibrational ground state. |
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N01.00034: Spectroscopy and coherent control of Rydberg-Rydberg transitions with a modulated optical lattice Ryan J Cardman, Georg A Raithel We discuss recent experimental progress involving the use of a 1064-nm, intensity-modulated optical lattice to drive Doppler-free Rydberg-Rydberg transitions with spatial selectivity at the order of the lattice period. Permitted by the A●A-term of the minimal coupling Hamiltonian, this drive provides a first-order coupling between two Rydberg states that is free of the usual l-selection rules. We discuss lattice-modulation spectroscopy of Rydberg nS1/2-nP1/2 transitions that inhibit on-resonant excitation due to a rotary-echo-like effect from the Rydberg-atom trajectory within the ponderomotive potential, while permitting excitations at vibrational sidebands. We further drive the nS1/2-(n+1)S1/2 transition by simultaneous application of a lattice modulation and a microwave field. In this case, the net transition amplitude is a coherent sum of both the A●A and the A●p interactions in the minimal coupling Hamiltonian. Experimental and numerical data are provided for both discussions. |
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N01.00035: Quantum dynamics of ultracold Li + CaF → LiF+ Ca chemical reaction Humberto da Silva, Masato Morita, Qian Yao, Hua Guo, Brian K Kendrick, Balakrishnan Naduvalath Calcium monofluoride is a prominent candidate for cold collision experiments due in part to its favorable Franck-Condon properties for laser cooling and magneto-optical trapping. |
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N01.00036: Design and Applications of a Zeeman-Sisyphus Decelerator Alexander J Frenett, Hiromitsu Sawaoka, Benjamin Augenbraun, Abdullah Nasir, Christian Hallas, Nathaniel B Vilas, Zack Lasner, John M Doyle Over the past decade, radiative slowing methods have been successfully applied to diatomic and, recently, triatomic molecules with highly diagonal Frank-Condon factors. Alternative slowing methods are needed for molecules that are less favorable for scattering the ~10,000 photons required for radiative slowing. Here, we provide the technical details of a superconducting-magnet-based Zeeman-Sisyphus decelerator that requires fewer than 10 photon scatters to slow molecules to velocities suitable for loading a MOT, magnetic, or electric trap. We describe the design considerations, apparatus construction, and application of the slower to both CaOH and YbOH molecular beams. We also discuss the generalizability of this slowing method to increasingly complex molecular species. |
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N01.00037: Towards laser-cooling and trapping of SrOH to probe ultralight dark matter Annika Lunstad, Zack Lasner, John M Doyle If dark matter is an ultralight scalar particle, it can coherently oscillate at its Compton frequency and induce a corresponding oscillation in the value of the proton-to-electron mass ratio, $\mu$. Since molecular rotational and vibrational energies depend on $\mu$, precise measurements of rovibrational spectra over time would reveal this signature of dark matter as a time-dependent resonance frequency. We anticipate that precision microwave spectroscopy of a trapped sample of SrOH molecules will provide ~$10^{-17}$ fractional sensitivity to changes in $\mu$ due to an accidental near-degeneracy between vibrational states. We report on high-resolution vibrational branching ratio measurements enabling the design of a laser-cooling scheme with over 10,000 photon scatters before loss to an unaddressed vibrational state–more than enough to form a MOT and load an optical trap. Only 8 lasers are required for this scheme, fewer than for any other known polyatomic molecule cooling cycle. We describe progress towards laser cooling and trapping of SrOH, the first step in a high-sensitivity measurement of $\mu$ variation using ultracold SrOH molecules. |
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N01.00038: Laser cooled polyatomic molecules for quantum science applications Paige K Robichaud, Loic Anderegg, Christian Hallas, Nathaniel B Vilas, Andrew Winnicki, John M Doyle The degrees of freedom inherent to polyatomic molecules allow for new applications spanning the fields of quantum simulation, ultracold chemistry, and precision measurement. For example, closely spaced opposite parity levels in low-lying vibrational states enable full polarization of the molecule at weak electric fields, which is highly desired for quantum science applications. Here we present progress towards optical trapping of CaOH molecules in the vibrational bending mode of the electronic ground state and discuss relevant spectroscopy of this state for its potential use in quantum simulation and computation. In addition, we discuss the creation of an optical tweezer array of CaOH molecules. The single particle control lent by this platform will open the door to future efforts studying interactions between molecules in optical traps. |
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N01.00039: Functionalizing Aromatic Compounds with Optical Cycling Centers Guo-Zhu Zhu, Debayan Mitra, Benjamin Augenbraun, Claire Dickerson, Michael Frim, Guanming Lao, Zack Lasner, Anastassia Alexandrova, Wesley C Campbell, Justin R Caram, John M Doyle, Eric R Hudson Optical cycling, a phenomenon where atoms or molecules quickly emit photons following optical excitation in a repeated cycle, plays a central role in laser cooling and trapping as well as state preparation and measurement. Recent theoretical work [1, 2] suggested aromatic compounds functionalized with a unit of M-O (M = Ca or Sr) for optical cycling can be made suitable for repeated photon scattering. Here, we report the production and characterization of such complexes M-O-R (R = phenyl, naphthyl, and the substituted variants) that have been suggested for optical cycling. We find that all functionalized complexes have diagonal vibrational branching fractions exceeding 90% for the transitions from the two-lowest electronic states to the ground state, which are promising for laser cooling. We describe how the excitation energies of substituted variants follow simple rules that ease their spectroscopic identifications. This work provides a way to utilize chemical functionalization to build molecules of increasing size, complexity, and function for quantum science and technology. |
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N01.00040: New methods for enhanced production of laser-coolable molecules Zack Lasner, Annika Lunstad, Abdullah Nasir, Derick Gonzalez-Acevedo, John M Doyle Radical polyatomic molecules can be produced from gas-phase atomic metal precursors in the presence of a reagent gas. Previous work with YbOH [1] and CaOH [2] has shown that molecular production in a cryogenic buffer-gas cell can be enhanced more than ten-fold by populating metastable triplet electronic states of metal atom precursors. These demonstrations, while highly effective, required excitation of weak intercombination (i.e., spin-flip) transitions. Here we report work exploring alternative pathways to populate these metastable states via two-step excitation on strong transitions followed by spontaneous decay to the target states. Candidate pathways have been identified for calcium- and strontium-containing molecules. We present our results measuring enhancement factors for production of several molecules used in ongoing molecular physics experiments. |
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N01.00041: A bright, cold and slow beam of CH radicals for laser cooling and trapping experiments Jamie Shaw, Joseph Schnaubelt, Daniel McCarron Techniques to directly laser cool and trap molecules at ultracold temperatures have revealed a new path towards the full quantum control of a diverse range of species with a variety of internal structures. Our experiment will capitalize on this generality by directly laser cooling and trapping CH radicals for tests of ultracold organic chemistry. The low mass and blue optical transitions in this species lead to high recoil velocities which can significantly reduce the required photon budget and rovibrational closure to slow, cool and trap a molecular beam from our cryogenic source. Here we will present our latest results probing in-cell CH interactions, characterizing our slow molecular beam and testing optical cycling protocols. |
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N01.00042: Laser cooling AlCl molecules in the deep-ultraviolet Jamie Shaw, Mark Semco, William Wortley, Daniel McCarron Laser-cooled molecules promise access to a diverse range of research directions from quantum simulation to controlled ultracold chemistry. Today, inefficient slowing of cold molecular beams remains a key barrier preventing molecular magneto-optical traps (MOTs) from trapping large, dense samples of ultracold molecules with properties similar to their atomic counterparts. Our experiment aims to remove this barrier by using bright continuous beams of cold molecules [1] and a molecular species susceptible to large optical forces by photon scattering. Our molecule of choice, aluminum monochloride (AlCl) has favorable properties for laser cooling and efficient trap loading, including a lack of spin-rotation structure and strong optical transitions in the deep-ultraviolet. Here we will present our latest work spectroscopically characterizing and manipulating a beam of AlCl with multiple high-power ultraviolet lasers [2]. |
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N01.00043: DEGENERATE GASES AND MANY-BODY PHYSICS
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N01.00044: A New Apparatus for Li Rydberg Gases Phillip Campos, Yu-Hao Yeh, Brian DeSalvo We present progress towards a new apparatus for creating and studying novel quantum matter. Featuring large optical access, precisely controllable magnetic and electric fields, and sensitive charged particle detection, our apparatus is designed to enable flexible control over Li-6 quantum gases coupled to highly excited Rydberg states. The tunable long- and short-range interactions available in this system via Rydberg dressing and magnetic Feshbach resonances will enable exploration of a broad range of strongly interacting many-body physics from quantum droplets to topological superfluids. In this poster, we present the design and simulation of a compact Zeeman slower for Li-6. Using the decreasing field configuration of a Zeeman slower, we use the magnetic field from the magneto-optical trap (MOT) to effectively overlap the end of the Zeeman slower with the MOT center. This configuration reduces the solid angle of the atomic beam and increases the loading rate of the MOT. We also present design and simulation of electric fields and charged particle detection in our apparatus. We implement a series of electrodes within the vacuum chamber to produce electric fields strong enough to ionize the Rydberg state atoms. The ionized electrons are then guided by the net electric field towards a micro-channel plate (MCP) detector which counts the Rydberg excitations. We model the resulting electric fields from the electrode geometry using software simulations in SIMION. The simulations allow us to predict the resulting electron trajectories for given electrode potential values and to focus the beam for optimal detection. |
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N01.00045: Apparatus for Non-Equilibrium Interfaces in Strongly Interacting Fermi Gases John R Griffin, Dadbeh Shaddel, Chris Angyal, Ian Crawley, Sarah McCusker, Hannah Clark, Ding Zhang, Cameron Brady, Ariel T Sommer Strongly interacting Fermi gases serve as a useful platform when exploring the transport properties of quantum many-body systems. Here we present our experimental apparatus and our proposed research into spin transport utilizing ultracold lithium-6 atoms. The work proposed here employs a repulsive multi-region trap to initialize the experiment with several regions of differing spin composition, separated by light sheets produced by a digital mirror device (DMD). This trap will allow us to investigate the bulk spin transport properties in normal and superfluid Fermi gases. Additionally, this configuration allows for controlled measurements of transport at normal-superfluid interfaces. Such interfaces serve as a model for normal-superconductor and ferromagnet-superconductor interfaces used in solid state junction devices with strongly correlated materials. We include our theoretical predictions for transport at the normal-superfluid interface based calculations employing the Blonder--Tinkham--Klapwijk (BTK) framework. |
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N01.00046: Quantum Joule-Thomson Effect in Universal Fermi Gases Yunpeng Ji, Gabriel Assumpção, Jianyi Chen, Grant Schumacher, Franklin Vivanco, Nir Navon We investigate the temperature dynamics of a homogeneous Fermi gas during energy-independent losses induced by collisions with background particles. For both ideal and unitary Fermi gases, the enthalpy is proportional to the total energy of the gas and the specific enthalpy is therefore conserved in the process, making it thermodynamically equivalent to a Joule-Thomson rarefaction. We perform the thermometry by time-of-flight imaging for the ideal Fermi gas and by radio-frequency spectroscopy for the unitary Fermi gas. We observe isoenthalpic heating for both ideal and unitary Fermi gases, in contrast to cooling previously observed in excited-population-saturated uniform Bose gases. |
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N01.00047: Hydrodynamic Properties of the Unitary Fermi Gas Eric Wolf, Huan Q Bui, Parth B Patel, Zhenjie Yan, Carsten Robens, Richard Fletcher, Martin W Zwierlein The unitary Fermi gas is a paradigmatic model for other strongly interacting Fermi systems, from atomic nuclei to neutron stars, and can be efficiently realized with ultracold atoms near a Feshbach resonance. Strong interactions and fermion antisymmetry render theoretical predictions highly challenging, in particular for transport properties such as density, spin, heat and momentum transport. Here, we prepare a spin-balanced, homogeneous gas of 6Li atoms at unitarity, trapped within a homogeneous box potential that removes complications from non-uniform density. We observe the response of the gas to local density and temperature perturbations in both the normal and superfluid phases and extract the associated diffusivities. In the degenerate regime, and near the superfluid critical temperature, these diffusivities attain a Heisenberg limit. This behavior contrasts with that expected for Fermi liquids, where instead diffusivities would strongly rise at low temperatures due to Pauli blocking. Our precision measurements of transport coefficients can serve as a benchmark for many-body theories of strongly interacting fermionic matter. |
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N01.00048: P-wave interactions in a spin-polarized Fermi gas with and without confinement Kevin G. S. Xie, Kenneth G Jackson, Colin J Dale, Ben A Olsen, Jeff A Maki, Shizhong Zhang, Denise Ahmed-Braun, Servaas Kokkelmans, Scott Smale, Paul S Julienne, Joseph H Thywissen Spin-polarized Fermi gases can only interact with exchange anti-symmetric pair wave functions. The resulting p-wave interactions are less well studied than the s-wave case. We improve our understanding and measure Feshbach resonance-enhanced p-wave interactions in fermionic Potassium (40K) with and without low-dimensional confinement. We first parameterize the three-dimensional (3D) resonance through a combination of coupled-channels calculations, a two-channel model, and dimer binding energies measured through resonant and spin-flip association. This benchmarks 3D interactions, which underlie lower-dimensional scattering. We attain confinement by loading atoms into two orthogonal standing waves to produce an ensemble of quasi-one-dimensional (q1D) tubes. We measure correlation strength through a connection between the power-law tail of radio-frequency transfer spectra and the 1D p-wave contact. Tuning of the magnetic field from the 3D resonance shows not only a confinement-induced resonance shift, but also additional features in a broader regime that arise due to collisions in transverse excited bands. Our studies build a foundation for further exploration of few- and many- body states in spin-polarized Fermi gases. |
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N01.00049: Phasonic control, dynamical localization and extended critical region using Floquet engineering with ultracold strontium gases Yifei Bai, Toshihiko Shimasaki, Hasan E Kondakci, Peter Dotti, Jared E Pagett, Max Prichard, David M Weld We report recent experimental studies of dynamics and localization using ultracold strontium atoms in an 1D bichromatic optical lattice. This system realizes the Aubry-André-Harper model, a prototypical tool for the study of localization, pseudo-disorder, and quasicrystals. Driving the phasonic degree of freedom unique to the quasicrystal, we have demonstrated coherent control of Aubry-André localization. Periodically pulsing the secondary optical lattice realizes the hitherto-unexplored kicked Aubry-André-Harper model. To explore the phase diagram of this model as a function of disorder strength and kick period, we developed a Floquet apodization technique. Applying this technique, we observe signatures of an extended critical regime of multifractal wavefunctions. |
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N01.00050: Observation of long-lived metastable structures in a quantum gas with long-range interactions Alexander Baumgärtner, Simon Hertlein, Davide Dreon, Xiangliang Li, Carlos Eduardo Máximo, Tom Schmit, Giovanna Morigi, Tobias Donner We study relaxation of a quantum gas after quenches across a phase transition and in the presence of competing long-range interactions. The interactions are mediated by two cavity modes, which induce competing spatial ordering. The quenches are implemented by changing the detuning between an external laser frequency and the cavity resonances. Using the real-time access to the order parameters provided by the leaking cavity fields, we observe metastability for a large range of parameters. The atoms remain frozen in the initial pattern with lifetimes that exceed any natural time scale of the system before relaxing to the stable configuration. From an ab-initio treatment we derive a Vlasov equation. We show that its fixed points are the metastable configurations, which can be understood as quasi-stationary states due to the long-range interactions. By this mean we theoretically reproduce the characteristic time scale of relaxation and their dependence on the physical parameters. We attribute the observed metastability to the competing global range interactions. |
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N01.00051: Towards Bose condensation in the flat p-band of an optical honeycomb lattice Shao-wen Chang, Malte Nils Schwarz, Charles D Brown, Rowan Duim, Dan Stamper-Kurn The orbital degree of freedom is important for understanding properties of condensed matter. In systems of atoms in optical lattices, many studies have been performed on the manifold of bands associated with the motional ground (lowest orbital) state of atoms in the wells – the so-called “s-bands”. The physics of higher orbital states in optical lattices have been studied theoretically for several lattice geometries, leading to the prediction of novel phases, such as complex Bose-Einstein condensates and topological semimetals. To date, experimental efforts on checkerboard and boron nitride lattices have already yielded fruitful results, including the observation of chiral superfluid and spontaneous time-reversal symmetry breaking, yet open questions remain. In this work, we present a way to prepare higher orbital states in a honeycomb lattice with arbitrary lattice translation. We study the dynamics of the system as atoms relax to the doubly degenerate energy minima in the lowest p-band of a honeycomb lattice, which is predicted to be exactly flat in the tight-binding limit. We propose an experimental scheme to observe Bose condensation in the lowest p-band, which could provide evidence on the effect of geometric frustration on band structure. |
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N01.00052: Probing Equilibrium and Dynamical Criticality Through Spatially Minimal Measurements Ceren B Dag, Philipp Uhrich, Yidan Wang, Jad C Halimeh Extracting critical behavior in the wake of quantum quenches has recently been at the forefront of theoretical and experimental investigations in condensed matter physics. Here, we investigate the potential of single-site observables in probing equilibrium phase transitions and dynamical criticality in short-range transverse-field Ising chains. For integrable and near integrable models, our exact analytical and numerical calculations reveal an out-of-equilibrium universal scaling exponent in the vicinity of the transition. We show that this scaling exponent stems from a critically prethermal temporal regime, and demonstrate its independence from the initial state and the location of the probe site so long as the latter is sufficiently close to the edge of the chain. We extend our analyses to strongly nonintegrable TFIC, with long-range power-law or next-nearest-neighbor interactions, using t-DMRG calculations. Both finite-size and finite-time analyses suggest a dynamical critical point for the strongly nonintegrable and locally connected TFIC. Our work provides a robust scheme for the experimental detection of quantum critical points and dynamical scaling laws in short-range interacting models. |
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N01.00053: Correlated dynamics of droplets in a harmonic trap Ilias Englezos, Simeon I Mistakidis, Peter Schmelcher We address the existence and dynamics of one-dimensional harmonically confined quantum droplets, that appear in two-component mixtures, deploying a nonperturbative approach. A transition from Gaussian-like to flat-top droplets occurs for varying intercomponent attraction in homonuclear settings, while flat-top signatures emerge at intermediate interactions due to beyond Lee-Huang-Yang correlations. For heteronuclear mixtures a pronounced mixing of the involved components takes place with the strongly interacting component exhibiting flat-top structures. An anti-bunching behavior is observed in the flat-top region, while two-body correlations are enhanced for larger interaction imbalances. Following quenches of the harmonic trap we monitor the development of the lowest-lying collective droplet excitations. The breathing mode is found to be unstable in the long time-evolution associated with the build-up of higher-lying excitations. Its frequency depends on the intercomponent attraction and it is found to be slightly reduced in the presence of correlations. In sharp contrast, the dipole motion of the droplet remains robust, while irregular dipole patterns are observed after the component collision in a species selective trap. |
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N01.00054: Emerging dissipative phases and spin currents in a superradiant quantum gas Fabian Finger, Rodrigo Rosa-Medina, Francesco Ferri, Tobias Donner, Tilman Esslinger The interplay between coherent and dissipative processes is at the core of the evolution of open many-body quantum systems. Their competition can lead to new phases of matter, instabilities, and non-equilibrium dynamics that have no closed system counterparts. However, probing these phenomena at a microscopic level in a setting of controlled coherent and dissipative couplings often proves challenging. |
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N01.00055: Experimental exploration of fragmented models and non-ergodicity in tilted Fermi-Hubbard chains. Bharath Hebbe Madhusudhana, Thomas Kohlert, Sebastian Scherg, Pablo Sala de Torres-Solanot, Frank Pollmann, Immanuel Bloch, Monika Aidelsburger Thermalization of isolated quantum many-body systems can be understood as a redistribution of quantum information within the system. In this redistribution, macroscopic variables acquire a thermal value, which is independent of the initial state, and remain experimentally accessible. While microscopic variables, that contain most of the details of the initial state recede into experimentally inaccessible parts of the observable space. Therefore, a question of fundamental importance to quantum information theory is when do quantum many-body systems fail to thermalize, i.e., feature non-ergodicity. A useful test-bed for the study of one type of non-ergodicity is the tilted Fermi-Hubbard model, which is directly accessible in experiments with ultracold atoms in optical lattices. Here we experimentally study non-ergodic behavior in this model by observing the evolution of an initial charge-density wave over a wide range of parameters, where we find a remarkably long-lived initial-state memory [1]. In the limit of large tilts, we identify the microscopic processes which the observed dynamics arise from. These processes constitute an effective Hamiltonian and we experimentally show its validity [2]. This effective Hamiltonian features the novel phenomenon of Hilbert space fragmentation. In the intermediate tilt regime, while these effective models are no longer valid, we show that the features of fragmentation are still vaguely present in the dynamics. |
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N01.00056: Coupled spin and density dynamics in a minimally doped Fermi-Hubbard system Martin Lebrat, Geoffrey Ji, Muqing Xu, Lev H Kendrick, Anant Kale, Justus Bruggenjurgen, Christie S Chiu, Daniel Greif, Annabelle Bohrdt, Fabian Grusdt, Eugene Demler, Markus Greiner The Fermi-Hubbard model is one of the simplest models capturing the spin and density dynamics occurring in highly-correlated electronic systems. Understanding its transport properties may shed light on emergent phenomena in cuprate materials, including bad metallic behavior and high-temperature superconductivity. Yet this task is notoriously challenging away from half-filling, even in the minimal case where a Mott insulator is doped with a single, initially localized hole. |
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N01.00057: Spontaneous defect formation in inhomogeneous trapped Bose gases Yangheon Lee, Tenzin Rabga, Myeonghyeon Kim, Dalmin Bae, Kyuhwan Lee, Kim Sol, Junhong Goo, Yong-il Shin Kibble-Zurek mechanism (KZM) provides a universal framework for describing the spontaneous defect formation in a system undergoing a continuous phase transition. Its extension to inhomogeneous systems is an interesting problem because the defect formation dynamics might be affected by the competition between the phase front propagation and the characteristic speed of sound of the system, and recently, it was predicted that the Kibble-Zurek (KZ) scaling exponent would be significantly modified by the trapping geometry of the system. In this poster, we describe our experimental study of the spontaneous vortex formation using trapped Bose gases of 87Rb and present the measurement results of the KZ exponent for various trapping potentials. Using a clipped Gaussian optical dipole trap, we controlled the aspect ratio and flatness of the trapping potential and observed the KZ exponent is changed accordingly but surprisingly, in an opposite direction to the theoretical prediction. We will discuss the implications of our observation on the inhomogeneous KZM and suggest directions for further investigations. |
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N01.00058: Floquet Engineering and Thermodynamics with Ultracold Lithium Eber Nolasco-Martinez, Ethan Q Simmons, Roshan Sajjad, Jeremy Tanlimco, Alec J Cao, Hector Mas, Toshihiko Shimasaki, Hasan E Kondakci, David M Weld We present results of recent experiments on quantum thermodynamics and thermalization using ultracold lithium BECs. We report the first experimental observation and characterization of the quantum boomerang effect, using an atom-optics kicked rotor realized with a pulsed optical lattice. Separately, we discuss progress towards studying quantum thermodynamic engines and realizing trapped-atom interferometry in “magic” Floquet-Bloch bands. |
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N01.00059: Direct Geometric Probe of Singularities in Band Structure of an Optical Honeycomb Lattice Malte Nils Schwarz, Charles D Brown, Shao-wen Chang, Tsz-Him Leung, Vladyslav Kozii, Aleksandr Avdoshkin, Joel E Moore, Dan Stamper-Kurn In certain real-space lattice geometries, such as in some solid-state crystals, the associated band structure can exhibit band degeneracies. In special cases these degeneracies, or band “touching points,” are associated with a singular Bloch state manifold with unusual consequences for material and transport properties. So far, ultracold atoms in optical lattices have been used to characterize such points only indirectly, e.g., by detection of an Abelian Berry phase, and only at singularities with linear dispersion (Dirac points). We probe the band structure directly by evolving Bose-condensed atoms over trajectories in momentum space such that they pass through band touching points. We vary the angle between the incoming and the outgoing ray with respect to the touching point and use this technique to probe linear and quadratic band touching points of a honeycomb lattice. Measurements of the band populations after this transport scheme lets us identify the winding numbers of these singularities to be 1 and 2, respectively. Our work opens the study of quadratic band touching points in ultracold-atom quantum simulators, and also provides a novel method for probing other band geometry singularities. |
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N01.00060: Observation of interaction-driven dynamical delocalization in the 1D and 3D Anderson models Jun Hui See Toh, Xinxin Tang, Tristan Rojo, Katherine C McCormick, Subhadeep Gupta The quantum kicked rotor is a paradigmatic system to study the Anderson model. Despite the wide interest in the Anderson model, the effect of interaction on the Anderson model has not been studied experimentally. We report the observation of interaction-driven dynamical delocalization in the 1D and 3D Anderson models. We load a 174Yb BEC into 1D tubes and pulse on a one-dimensional lattice along the axial direction of the tubes. We vary the 2D lattice depth to control the number density, and hence the interaction, and then measure the energy of the atom cloud after some number of kicks. By modulating the pulse amplitude with two other incommensurate frequencies, we can simulate the 3D Anderson model, which is known to display a metal-insulator transition. We show that for both the 1D and 3D Anderson models, the addition of interaction breaks down the localized state and turns the dynamics subdiffusive. Our study of the effect of interaction on the Anderson model for different interaction strengths, kick strengths, and modulation amplitudes sheds light on understanding the transport dynamics of interacting particles in a disordered medium. |
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N01.00061: Rotating Bose gas dynamically entering the lowest Landau level Vaibhav Sharma Motivated by recent experiments, we model the dynamics of a condensed Bose gas in a rotating anisotropic trap, where the equations of motion are analogous to those of charged particles in a magnetic field. As the rotation rate is ramped from zero to the trapping frequency, the condensate stretches along one direction and is squeezed along another, becoming long and thin. When the trap anisotropy is slowly switched off on a particular timescale, the condensate is left in the lowest Landau level. We use a time dependent variational approach to quantify these dynamics and give intuitive arguments about the structure of the condensate wavefunction. This preparation of a lowest Landau level condensate can be an important first step in realizing bosonic analogs of quantum Hall states. |
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N01.00062: Universal quench dynamics in attractive two-dimensional Bose gases Cheng-An Chen, HIKARU TAMURA, Chen-Lung Hung We experimentally study universal non-equilibrium dynamics of homogeneous two-dimensional (2D) Bose gases quenched from repulsive to attractive interactions. We show that the interaction quench induces an instability that stimulates emission of quasiparticle pairs from a degenerate 2D gas. Using in situ density noise measurements, we present direct characterization of coherence and quantum entanglement between interaction quench generated quasiparticles. Moreover, we show that the initial quasiparticle emission and instability eventually lead to amplified density waves and fragmentation of a 2D sample. We observe formation of 2D matter-wave Townes solitons that were previously considered impossible to prepare in equilibrium. Our studies unveil a set of scale-invariant and universal scaling behaviors in the quench dynamics. We further discuss how our experimental platform could be extended to explore non-equilibrium physics and observe intricate many-body effects such as quantum critical transport in a homogenous quantum gas. |
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N01.00063: Persistent Currents in a Spin-Imbalanced Ultracold Fermi Gas in a Ring Parth Sabharwal, Daniel G Allman, Kevin C Wright We will present the results of experiments involving the creation and decay of persistent currents in a spin-imbalanced Fermi gas in a ring. Variations in the depth of the trapping potential generally cause accumulation of the majority spin component in shallower regions of the ring, which affects the stability of persistent currents and the response of the system to rotating perturbations. We hope to achieve conditions where a sufficiently localized repulsive potential acts as a magnetic impurity, forming a π-Josephson junction and a spontaneous current in the ground state. We will report on progress toward these goals. |
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N01.00064: Imaging FFLO Domain Walls in a Quasi-1D Spin-Imbalanced Fermi Gas Bhagwan D Singh, Jacob A Fry, Randall G Hulet The Fulde-Ferrell Larkin-Ovchinnikov (FFLO) polarized superconductor is predicted to exhibit both superconducting and magnetic order. We explore this elusive state of matter using quantum simulation: hyperfine sublevels of 6Li are stand-ins for the electrons, and a 2D optical lattice creates an array of quasi-1D tubes. The excess spin-up atoms are expected to localize in periodic domain walls for the LO phase. We seek to directly image these domain walls via polarization phase contrast imaging (PPCI). We first load a degenerate sample of 6Li atoms into a 2D optical lattice with a very long aspect ratio, with a controllable spin-imbalance between two hyperfine levels. By varying the inter-tube tunneling rate via a Feshbach resonance and the lattice depth, it may be possible to lock the phase of the domain wall oscillations in adjacent tubes, and thus enabling coherent averaging the signal. By using FFT’s combined with data averaging techniques, we hope to reveal the periodic domain wall structure. |
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N01.00065: Classical Hydrodynamics and Coarse-Grained Quantum Turbulence Edward Eskew, Saptarshi Sarkar, Khalid Hossain, Gabriel Wlazlowski, Piotr Magierski, Michael M Forbes Pulsar glitches are not fully understood, but likely are related to instabilities in a coarse-grained hydrodynamic description of superfluids present in neutron stars. In this work, I will address how classical hydrodynamic turbulence emerges by coarse-graining microscopic simulations of quantum turbulence. We investigate both bosonic superfluids, described by the Gross-Pitaevskii Equation (GPE), and fermionic superfluids, modeled by the Superfluid Local Density Approximation (SLDA). |
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N01.00066: Superradiant phase transitions in one-dimensional correlated Fermi gases with cavity-induced umklapp scattering Jian-Song Pan Superradiant phase transitions of one dimensional correlated Fermi gases in a transversely driven optical cavity, under the umklapp condition that the cavity wavenumber equals two times of Fermi wavenumber, are studied with the bosonization and renormalization group (RG) techniques. The bosonization of Fermi fields gives rise to an all-to-all sine-Gordon (SG) model due to the cavity-assisted non-local interactions, where the Bose fields at any two spatial points are coupled. The superradiant phase transition is then mapped to the Kosterlitz-Thouless phase transition of the all-to-all SG model. The nesting effect, in which the superradiant phase transition can be triggered by infinitely small atom-cavity coupling strength, is shown to be preserved for any non-attractive local interactions. For attractive local interactions, the phase transition occurs at finite critical coupling strength. Nevertheless, the analysis of scaling dimension indicates that the perturbation of non-local cosine term is indeed relevant (irrelevant) when the scaling dimension is lower (higher) than the critical dimension, similar to the case of ordinary local SG model. Our work provides an analytical framework for understanding the superradiant phase transitions in low-dimensional correlated intra-cavity Fermi gases.s |
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N01.00067: GENERAL PRECISION MEASUREMENTS
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N01.00068: Validation of the cold atom vacuum standard Bishnu P Acharya, Daniel S Barker, Eite Tiesinga, Nikolai N Klimov, James A Fedchak, Julia Scherschligt, Stephen P Eckel We report the progress towards the validation of the new cold atom vacuum standard (CAVS) via comparison to a dynamic expansion pressure standard. The CAVS is a primary pressure standard capable of sensing ultra-high vacuum (≲ 10-6 Pa) and extreme-high vacuum (≲ 10-9 Pa) using laser-cooled atoms (rubidium and lithium). The CAVS measures the background-gas-induced loss rate of laser-cooled atoms from a magnetic trap, which is converted to pressure using loss-rate coefficients calculated from first-principles quantum scattering theory. To validate the CAVS, we use it to measure a known pressure of a known background gas generated by a combination of flowmeter and dynamic expansion system. This system produces known partial pressures that are compatible with atom trapping (<10-6 Pa). Here, we present our initial measurements and discuss future plans for a three-way comparison of the laboratory-scale CAVS, the dynamic expansion system, and a portable version of the CAVS meant to replace the Bayard-Alpert ionization gauge. |
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N01.00069: Testing fundamental physics with charged particle nano-oscillators Peter Barker, Antonio Pontin, Thomas Penny, Marko Toros, Nathanael Bullier I will describe experiments that use nanoparticle oscillators formed by trapping a single or two charged silica nanoparticles in a Paul trap. The oscillators operate in high vacuum, and at room temperature, with microhertz mechanical linewidths. We characterise the important noise sources for this oscillator and outline a means to achieve even lower linewidths and higher mechanical quality factors for future experiments that aim to test the macroscopic limits of quantum mechanics. The stability of this oscillator, and our measurement of this ultra-narrow linewidth as a function of residual gas pressure, allows us to put experimental bounds for the first time on both the dissipative continuous spontaneous localisation and Diosi-Penrose models. Lastly, we demonstrate and compare different feedback cooling methods for a single oscillator and show how feedback cooling of a single co-trapped nanoparticle can be used to sympathetically cool the motion of the other oscillator. We show that this strong coupling can also be used for sympathetic squeezing and describe important future applications. |
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N01.00070: Novel atomic and molecular systems for radiative thermometry Stephen P Eckel, Eric Norrgard, Kyle P Beloy, Andrew Ludlow, Matthew T Simons, Christopher L Holloway, Eric L Shirley, Howard Yoon, Dazhen Gu, Adam M Kaufman Radiative (non-contact) thermometry currently relies on classical radiation detectors, which are typically calibrated through long traceability chains that require constant upkeep. These requirements have posed a variety of problems in fields like remote sensing, where constant recalibration of detectors is not possible. Instead, we are attempting to realize standards for radiative thermometry based on either Rydberg atoms or polar molecules. For the former, we are pursuing multiple measurement techniques, including thermal radiation induced state transfer and Stark shifts in both rubidium and ytterbium atoms. These systems are most sensitive to thermal radiation in the microwave (10 GHz to 1 THz) regimes and can potentially produce new radiation probes for climate monitoring, weather prediction, and more accurate mobile atomic clocks, among other applications. For the latter, we are pursuing laser-cooled MgF molecules, which would be sensitive in the near-IR. MgF offers several advantages for laser cooling, including larger optical forces, large accelerations, and high capture velocities. When combined, MgF offers the potential for a large number of trapped molecules, enhanced sensitivity, and a new radiometric standard traceable directly to the SI. |
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N01.00071: Search Efforts for the 229Th Isomeric Transition Ricky Elwell, Christian Schneider, Justin Jeet, Galen O'Neil, Varun Verma, Dileep V Reddy, Sae Woo Nam, Alina Heihoff, Raphael Haas, Dennis Renisch, Christoph Düllmann, Lars von der Wense, Benedict Seiferle, Florian Zacherl, Peter G Thirolf, Eugene Tkalya, Eric R Hudson The nucleus of 229Th has an exceptionally low-energy isomeric transition in the |
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N01.00072: VHF/UHF detection using high angular momentum Rydberg states Robert Wyllie, Baran Kayim, Brian C Sawyer, Roger Brown, Abigail Perry, Michael A Viray We demonstrate resonant detection of rf electric fields using electromagnetically induced transparency in 87Rb with L=3 to L'=4 Rydberg states. These Rydberg states are accessible with three-photon infrared optical excitation. By reducing the rf carrier frequency from the GHz range, these Rydberg states enable a broader class of electrically small atomic receivers. We assess sensitivity limits and prospects for further reduction of on-resonant carrier frequencies. |
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N01.00073: Rydberg Atoms for Blackbody Sensing and Quantum Thermometry David La Mantia, Matthew T Simons, Christopher L Holloway, Eric Norrgard, Stephen P Eckel A ubiquitous source of incoherent radiation is blackbody radiation (BBR), described quantitatively less than two centuries ago to specify thermal bodies. It therefore follows that characterizing BBR is an appropriate technique to accurately assess the temperature of a distant entity. Classical thermal radiation detectors suffer from a number of systematic sources of error and long traceability chains. A thermal radiation detector integrating an invariable quantum system clearly represents the next technological leap in radiation thermometry while being directly traceable to the new International System (SI) of units. Rydberg atoms are a natural tool to use in electrometry as radiation sensors due to their enhanced physical properties. Efforts are underway at NIST to use Rydberg atoms as calibration-free, SI-traceable sensors of thermal radiation, thereby characterizing reference blackbodies at the 100 ppm level1 and greatly reducing the calibration uncertainty for classical thermal radiation sensors. Furthermore, this sensor may serve to reduce the Stark shift uncertainty in atomic clocks due to BBR, the largest systematic error in those systems to date. Realizing the kelvin in this manner requires merging a vapor cell and appropriate laser systems to observe blackbody-induced transitions through selective-field ionization or fluorescence measurements. |
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N01.00074: Isotope shifts and hyperfine structure measurements in low-lying transitions of atomic lead John H Lacy, Charlotte Jones We recently completed the first ever direct measurement of the 939 nm (6s26p2) 3P0 - 3P2 electric quadrupole (E2) transition in Pb, using Faraday rotation spectroscopy. We found our measured E2 amplitude to be in excellent agreement with the theoretical value predicted from a new ab initio calculation at the 1% level of accuracy [1]. Continuing our exploration of this transition, we have recently completed a measurement of the 939 nm E2 transition isotope shift (TIS) among several stable isotopes of lead as well as the 207Pb hyperfine constant for the 3P2 excited state. A value for these isotope shifts can be inferred by combining several published measurements of TIS values for other low-lying transitions, and we have found our direct measurement to be in significant disagreement with these inferred values. Using several complementary methods for laser frequency scan calibration and linearization, we have expanded our scope to measure TIS and hyperfine structure in multiple low-lying transitions in lead using both direct absorption and Faraday rotation spectroscopy, and employing several different IR, blue, and near-UV diode laser systems. Comparisons to previous measurements and latest results will be presented. |
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N01.00075: Progress Towards a Single Atom Microscope for Nuclear Astrophysics Jaideep T Singh, Julia Egbert, Keara M Hayes, Nick Koester, Ben Mellon, Joseph Noonan, Roy A Ready, Payton Walton, Erin E White We are developing the technique of optically detecting individual atoms embedded in thin films of cryogenically frozen solids. Noble gas solids such as frozen neon or kypton are an attractive medium because they are optically transparent and provide efficient, pure, stable, & chemically inert confinement for a wide variety of atomic and molecular species. The excitation and emission spectra of atoms embedded in solids can be separated by up to hundreds of nanometers making optical single atom detection feasible. We propose to couple a single atom microscope (SAM) detector to an electromagnetic recoil separator with the goal of measuring rare nuclear reactions relevant for nuclear astrophysics. The electromagnetic recoil separator would minimize the heat load on SAM while allowing for isotope discrimination. This technique has the potential to capture and detect every product atom with near unity efficiency. Because of the additional selectivity provided by resonantly exciting the atomic transitions of the captured product atom, SAM would have a negligible false positive rate which would help loosen the often demanding beam rejection requirements imposed on electromagnetic recoil separators. Our current goal is to calibrate the brighness of Rb atoms in solid Kr. We will describe the SAM concept in more detail, summarize our findings regarding the growth of transparent noble gas films, and our current efforts towards spectroscopy of Rb in solid Kr. This work is supported by the U.S. National Science Foundation under grant number #1654610. |
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N01.00076: Direct probe of spin polarization in potassium for beta decay Felix Klose, John A Behr, Dante M Prins, Andrew J Kovachik Motivated by the need for a more precise measurement of beta, neutrino and nuclear recoil asymmetries to probe new physics, we report on a new technique to measure the spin polarization of potassium by directly probing the 4s1/2 → 5p1/2 hyperfine transitions using a 405 nm π-light probe laser. Our previous method [B. Fenker et al. Phys Rev Lett 120 062502 (2018) Supp Mat] monitors the near-extinction of spontaneous fluorescence from 4S1/2 → 4P1/2 optical pumping as the atoms become polarized [B Fenker et al 2016 New J. Phys. 18 073028 (2016)] using the fluorescence data in a complex model to determine the average polarization of our atom cloud. With the new optical probing method we are able to directly probe the populations of the individual 4S1/2 sublevels, resulting in a direct measurement of the sample polarization. This makes our new method a lot more flexible when it comes to different optical trap and pumping configurations, as there is no need to re-determine the parameters of the model. Using this new technique, we were able to directly measure potassium spectra with different optical pumping and MOT configurations. |
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N01.00077: Progress on the JILA Generation III eEDM Experiment Sun Yool Park, Kia Boon Ng, Noah Schlossberger, Anzhou Wang, Benjamin D Hunt, Tanya Roussy, Trevor Wright, Luke A Caldwell, Antonio Vigil, Gustavo Santaella, Jun Ye, Eric A Cornell The new generation (Gen. III) apparatus for the measurement of the electron electric dipole moment (eEDM) at JILA utilizes ThF+, rather than HfF+, because: (i) the eEDM sensitive state of ThF+ promises a longer coherence time (~ 20 seconds) [1,2,3], and (ii) its 50% larger effective electric field increases eEDM sensitivity [4,5]. The new experimental apparatus consists of a "conveyor belt” of 100 consecutive ion traps, named the Bucket Brigade, which will continuously load and read out ThF+, allowing for an increased duty cycle without compromising long interrogation times [3]. We are currently constructing a small-scale prototype. Here, we present our experimental designs of the prototype to produce the highly uniform electromagnetic fields required to observe the 20-second coherence time. We also present our current designs for ion translation and ion detection of the photodissociated products for the Gen. III eEDM experiment at JILA. |
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N01.00078: Progress towards in-line detection along dominant decay path for the 5S1/2 - 5D5/2 two-photon rubidium clock River Beard, Kyle W Martin, John D Elgin, Sean P Krzyzewski Clocks built upon the 5S1/2-5D5/2 Doppler free two-photon transition in rubidium are promising candidates for navigation, communications, and other extra-laboratory applications. The most common current method to stabilize to the transition is through fluorescence detection of a decay path yielding 420 nm photons. However, this is not the dominant decay path, leading to small signals that require a high voltage photo-multiplier tube and larger optical powers. The dominant decay path, through the 5P3/2 state, produces ~12x more fluorescence at 776 nm, unfortunately, only 2 nm de-tuned from the 778 nm excitation laser. Detection at 776 nm would allow for a lower intensity probe beam without the loss of signal-to-noise ratio, potentially leading to a reduction of ac-Stark shifts. Moreover, detection at 776 nm allows the use of a multi-pixel photon counter, eliminating the need for a high voltage photo-multiplier tube. We present progress towards implementing a clock detecting the 5D5/2-5P3/2 decay at 776 nm with in-line geometry using high OD, sharp cut-off filters and a multi-pixel photon counter. |
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N01.00079: A Two-Photon Optical Atomic Clock based on Direct Comb Spectroscopy Seth Erickson, R. Jason Jones, Dylan P Tooley We present progress on direct comb spectroscopy (DCS) of the 5S1/2 to 5D5/2 two-photon transition in Rubidium-87 as an optical atomic clock. The use of DCS eliminates the need for cw laser excitation of the clock transition while the broad spectrum provides light at multiple wavelengths that can be utilized for ac-Stark shift mitigation or removal of the Doppler background. Low size, weight, and power frequency standards are an enabling technology for many future systems, including next generation GPS. DCS benefits from efficient frequency doubling of ultrashort pulses from reliable laser sources at telecom wavelengths, and the potential for novel multiwavelength techniques. By carefully tailoring our comb bandwidth , we demonstrate narrow linewidth two-photon clock excitation linewidths comparable to those achieved with cw excitation and capable of supporting next generation high stability clocks. We also present experimental findings on the wavelength dependence of the ac-Stark shift around the two-photon transition, towards verifying the proper intensity ratio between a Stark shift mitigation beam and the frequency comb probe. |
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N01.00080: Record Precision in a 1D Optical Lattice Clock Kyungtae Kim, Alexander G Aeppli, Tobias Bothwell, Colin J Kennedy, John M Robinson, Jun Ye We report on the experimental progress of the JILA strontium 1D optical lattice clock. Our gravity-titled shallow lattice allows us to precisely control the interactions of the atoms and the resulting frequency shift. By analyzing the image of the atomic cloud, we account for various spatial inhomogeneities of the system including the atomic density. By tuning atomic interactions, we obtain ‘magic’ lattice depth where the density shift of the fractional frequency is canceled down to 5E-21 per atom [1]. Furthermore, we compare two regions of the cloud self synchronously, resolving the frequency gradient from the gravitational redshift across a 1 mm scale atomic ensemble [2]. These results bode well for a systematic accuracy evaluation at the 19th digit. Toward that end, we will present recent work on and progress towards measuring the lattice light shift and black body radiation shifts in our system. |
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N01.00081: Towards spin-squeezed metrology with a strontium optical lattice clock Maya Miklos, John M Robinson, Yee Ming Tso, Josephine Meyer, Colin J Kennedy, Tobias Bothwell, James K Thompson, Jun Ye Utilizing entangled states of a spin ensemble in atomic clock spectroscopy offers a fundamental improvement to the ultimate bound of clock stability. Yet the technical challenges of building such a device are considerable: besides contending with the limits of local oscillator precision and the supreme sensitivity to environmental disturbance present in every state-of-the-art optical lattice clock, one must engineer a mechanism for turning on many-body interactions without decohering the ensemble. Here, we report on the construction of a new state-of-the-art strontium optical lattice clock inside a high-finesse optical cavity. We discuss progress in generating spin-squeezed states via cavity-mediated quantum non-demolition measurements of the collective spin state, and work towards incorporating these spin-squeezed states into clock operation. Our goal is to demonstrate the achievement of improved metrological sensitivity using a spin-squeezed ensemble compared to a coherent spin state operating at the standard quantum limit. |
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N01.00082: Towards an improved measurement of the 8 eV Thorium-229 nuclear isomer transition energy using a superconducting detector Sayan Patra, Benedict Seiferle, Dileep V Reddy, Sae Woo Nam, David Leibrandt, Galen O'Neil The presence of a low-lying metastable state (229mTh) at 8 eV [1] above the nuclear ground state in Thorium-229 provides an opportunity to construct a nuclear clock by leveraging state-of-the-art AMO physics techniques, which is expected to be more accurate than the 10-19-level accuracy of the current best atomic clocks [2]. This nuclear clock will further enable studies of physics beyond the Standard Model, as this clock transition is predicted to exhibit enhanced sensitivity to time-variation of the Electromagnetic and Strong interaction coupling constants. However, the 0.17 eV (2%) uncertainty in the knowledge of the transition-energy [3] severely precludes direct excitation of this weak transition using spectrally narrow radiation sources. Here, we present an ongoing effort towards directly measuring the de-excitation energy of 229mTh using a superconducting nanowire single photon detector. Our target uncertainty of 0.01 eV or better will pave the way for a direct excitation of the nuclear transition, eventually leading to a nuclear clock. |
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N01.00083: Proposal for a cesium lattice optical clock Arjav Sharma, Shimon Kolkowitz, Mark Saffman Optical atomic clocks have demonstrated orders of magnitude enhancements in precision and accuracy compared to the microwave atomic clocks currently used as frequency standards and for most applications of time-keeping. Making high-performance optical atomic clocks more transportable by reducing their size, weight and power consumption (SWaP) could be transformative for many of these applications. We propose a cesium lattice optical clock (CLOC) using a forbidden transition in Cs atoms at 685 nm. The operation of this clock has the potential to be greatly simplified over current optical atomic clocks, requiring only two convenient diode laser wavelengths. We will present theoretical projections of the achievable stability and accuracy of the CLOC, which we predict to be on par with or superior to the very best microwave frequency standards. |
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N01.00084: A relativistic exact two-component approach for calculation of electronic g-factors with applications to f-element molecules pertinent to search for new physics Lan Cheng An exact two-component (X2C) approach for calculations of electronic g-factors together with applications to heavy metal containing small molecules relevant to search for new physics is presented. A magnetic-field-dependent unitary transformation of the Dirac Hamiltonian is adopted to enable a simple inclusion of the quantum electrodynamics correction to the electron spin g-factor in the four-component formulation. The X2C transformation is subsequently employed to eliminate the positronic degrees of freedom to enhance computational efficiency without significant loss of accuracy compared with the parent four-component theory. To demonstrate the accuracy and usefulness of the present scheme, spin-orbit coupled cluster calculations for g-factors of representative small molecules relevant to precision measurement for search of new physics, including HfF+, ThF+, and ThO, are presented. |
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N01.00085: Optically-trapped nanoparticles as scanning force sensors for conductive surfaces at sub-micron distances William Eom, Cris Montoya, Eduardo Alejandro, Daniel Grass, Nicolas Clarisse, Apryl Witherspoon, Andrew A Geraci We describe a method for 3-D scanning force sensing near a conductive surface with a levitated silica nanoparticle. Levitated nanoparticles are well decoupled from the environment, making them ideal precision sensors. 3-D positioning of a levitated nanosphere near a conductive surface could enable attonewton-level scanning force microscopy, precision tests of Yukawa-type corrections to gravity at micron distances, measurement of Casimir forces and characterization of patch potentials. We trap a ~170 nm diameter silica nanosphere in an optical tweezer trap, and transfer it into an optical lattice by introducing a gold-coated silicon surface to retroreflect the laser beam. The nanosphere can be trapped from a quarter of the laser's wavelength to tens of microns away from the conducting surface, and a piezo-driven mirror allows us to scan in 2-D parallel to the surface while maintaining attonewton-level force sensing. |
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N01.00086: Results of the search for topological dark matter using atomic clock data from the global positioning system Jiten Singh, Kalia M Pfeffer, Tyler Daykin, Geoffrey Blewitt, Benjamin M Roberts, Andrei P Derevianko We use the Global Positioning System (GPS), comprised of nominally 32 atomic microwave clocks, as a 50,000 km-diameter network of quantum sensors capable of searching for exotic physics, such as “clumpy” dark matter (DM). We search for ultralight, self-interacting quantum fields that form macroscopic DM objects, e.g., 2D domain walls. Encounters between the GPS constellation and 2D domain walls would cause a sequence of atomic clock perturbations, imprinting a certain sweeping signature across the network. Recently, we have performed a search for these DM signatures, investigating 20 years of archival GPS atomic clock data. Our statistical analysis uses two filters: (i) a signal-to-noise (SNR) filter and (ii) a χ2 filter. The SNR threshold imposes a rate of false positives to one in 100 years, and the χ2 threshold eliminates poor template matching for DM candidate events. Finally, events that pass both filters undergo parameter estimation, where speed and angles of incidence are determined. The results of our GPS.DM search will be presented at the conference. |
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N01.00087: The HUNTER Sterile Neutrino Search: Progress Towards a 131-Cs Decay Source Eddie Chang, Eric R Hudson, Paul Hamilton, Christian Schneider, Peter F Smith, Graciela B Gelmini, Alexander Kusenko, Kevork N Abazajian, Charles J Martoff, Francesco Granato, Victoria Palmaccio, Xunzhen Yu, Andrew L Renshaw, Frank Malatino, Peter D Meyers, Basu Lamichhane, Guy Ron The HUNTER experiment (Heavy Unseen Neutrinos by Total Energy-Momentum Reconstruction) is a search for sterile neutrinos with keV-scale mass. We will measure on 131-Cs radioactive decays to reconstruct their electron neutrino missing mass, with a probability of measuring a keV sterile neutrino proportional to the coupling sin2(θe4). Charged decay products will be measured by reaction-microscope spectrometers with high solid angle, and the trigger x-ray will be detected using scintillator and silicon photomultiplier arrays, all with sufficient resolution to reconstruct a keV missing mass. The 131-Cs decay source will consist of an actively controlled MOT. The 9.7 d half-life of 131-Cs, along with the goal of running the experiment continuously for one year, present unique challenges for the MOT. We will present progress on the MOT system being developed at UCLA, including demonstration of an efficient thermionic emission-based atomic source. |
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N01.00088: Precise transition amplitude and polarizability measurements in 208Pb John H Lacy, Protik K Majumder, Gabriel Patenotte Recently, we completed a measurement of the forbidden (6s26p2) 3P0 - 3P2 electric quadrupole (E2) transition amplitude in Pb as a new test of ab initio atomic theory work in this Group IV atom[1]. There, we compared the E2 absorptivity to the precisely-calculable (and comparably-weak) M1 transition absorptivity. We have now begun to study several excited-state E1 transitions in lead (at 368 and 406 nm). By choosing E1 transitions which originate in states whose thermal populations in our heated quartz cells are in 10-4 to 10-6 range, the observed absorptivity of these E1 transitions is comparable to the ‘forbidden’ ground-state transitions noted above. Through precise measurement of Faraday optical rotation amplitudes at carefully-monitored interaction region temperatures, we can convert relative absorptivity measurements into absolute E1 linestrength values. Preliminary results for two excited-state E1 transition amplitudes will be presented. We also present our continuing progress towards high-precision polarizability measurements in Pb using Faraday Rotation spectroscopy from an atomic beam apparatus, which we hope will serve as a new test of atomic wavefunction models in this heavy, multivalence atomic system. |
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N01.00089: Measurement of the hyperfine coupling constants and absolute energies of the 12s 2S1/2, 13s 2S1/2, and 11d 2DJ levels in atomic cesium Jonah Quirk, Amy Damitz, Carol E Tanner, Daniel Elliott We report measurements of the absolute energies of the hyperfine components of the 12s 2S1/2 and 13s 2S1/2 levels of atomic cesium, 133Cs. Using the frequency difference between these components, we determine the hyperfine coupling constants for these states, and report these values with a relative uncertainty of ∼0.06%. We also examine the hyperfine structure of the 11d 2DJ (J = 3/2, 5/2) states, and resolve the sign ambiguity of the hyperfine coupling constants from previous measurements of these states. We also derive new, high precision values for the state energies of the 12s 2S1/2, 13s 2S1/2 and 11d 2DJ states of cesium. |
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N01.00090: Progress Towards Measuring the Nuclear Spin Coherence of Molecules in Solid Parahydrogen Alex Rollings, Jonathan Weinstein Prior work has shown that alkali atoms trapped in solid parahydrogen exhibit long electron spin coherence times [Physical Review A 100, 063419 (2019)]. Likewise, previous experiments have shown that the nuclear spin coherence of HD molecules in solid parahydrogen matrices was limited by the presence of orthohydrogen impurities [Journal of Low Temperature Physics 45, 167 (1981)]. We have demonstrated the ability to grow solid hydrogen samples with orthohydrogen fractions that are orders-of-magnitude lower than this prior work [Review of Scientific Instruments 92, 073202 (2021)]. The objective of our current research is to use NMR techniques to measure the nuclear spin coherence times of molecules trapped in these high-purity parahydrogen matrices. If, as expected from prior work, long coherence times are achieved, this would be of interest for quantum sensing and fundamental physics measurements. Construction of an apparatus capable of measuring nuclear spin coherence times and our progress towards this goal will be discussed. |
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N01.00091: Progress towards a measurement of the nuclear anapole moment in cesium Amy Damitz, Jonah Quirk, Carol E Tanner, Daniel Elliott We report progress towards a measurement of the anapole moment in cesium, 133Cs. We will be using an atomic beam interacting with an rf field and Raman field that are coherent with each other. The rf field will drive a weak electric dipole interaction between the hyperfine components of the ground state of cesium (6s2S1/2 F=3 → 6s2S1/2 F=4), which is weakly allowed due to the nuclear anapole moment. The Raman field will initialize the atoms in a 50-50 mixed state between the two hyperfine ground states. We use detailed numerical calculations of the rf field modes in a cavity and numerical integration of the equations of motion of the state amplitudes to calculate the expected magnitude of the Bloch vector. We show sinusoidal modulation of the relative population of the two ground states with the phase of the rf field, relative to the phase of the initial superposition state imposed from the Raman interaction. The magnitude of this modulation is ≈ 5 x 10-6, which we show to be measurable in the laboratory. We have investigated and shown coherent interaction between two Raman interactions. |
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N01.00092: A High Finesse Cryogenic Sapphire Cavity for Ytterbium Optical Atomic Clocks Tanner Grogan, Chun-Chia Chen, Daniele Nicolodi, Xiaogang Zhang, Youssef Hassan, Jacob Siegel, William F McGrew, Andrew Ludlow The short-term stability of virtually all optical atomic clocks is currently limited by the coherence time of the interrogation laser. Achieving laser stability well below the 10-16 fractional frequency level will advance next-generation clocks for tests of fundamental physics, mapping Earth's geopotential, and redefining the SI second. Cryogenic optical cavities based on silicon have had some success realizing improved stability via reduced thermal noise effects. Here, we report on development of a cryogenic sapphire optical cavity to stabilize the interrogation laser for NIST's 171Yb optical lattice clocks. Sapphire has an extremely low coefficient of thermal expansion of 10-10 K-1 at 4K, is transparent in the NIR and visible domains, and is extremely rigid, making it an ideal material for designing a highly stable reference cavity at cryogenic temperatures. We present progress towards achieving sub-10-16 stability with a 4 K cryogenic sapphire cavity with finesse of 255,000. |
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N01.00093: Performance of a silicon photomultiplier module for the ACME III electron EDM search Ayami Hiramoto, Daniel G Ang, David DeMille, Collin Diver, John M Doyle, Gerald Gabrielse, Zhen Han, Peiran Hu, Nicholas R Hutzler, Daniel D Lascar, Siyuan Liu, Takahiko Masuda, Cole Meisenhelder, John Mitchell, Cristian D Panda, Noboru Sasao, Satoshi Uetake, Maya Watts, Xing Wu, Koji Yoshimura A measurement of the electron electric dipole moment (eEDM) is a powerful probe for the existence of physics beyond the Standard Model of particle physics. The ACME experiment searched for the eEDM with the world's highest sensitivity using cold ThO polar molecules (Nature, 562 (2018) 355-360). One of the improvements for the next generation of the ACME experiment is using silicon photomultipliers (SiPMs) as laser-induced fluorescence photon detectors instead of PMTs. We have developed a dedicated SiPM module and evaluated its performance. The SiPM module shows about 2.5 times higher detection efficiency than the PMTs used in the previous ACME measurement. Here we report on the design and performance of the SiPM module. |
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N01.00094: Surface Roughness Electric Field Noise and Total Noise Effects on Decoherence Time in NV Center Diamond Applications Philip C Chrostoski, Ifeanyi Onwosi, Deborah H Santamore Noise is a detrimental issue for nitrogen vacancy (NV) center diamond sensing devices. We study the effects of the varying charge density fluctuations and photon scattering caused by the rough surface on the noise spectrum. We apply the Schottky approximation with trapped charge density statistics to calculate and analyze the varying charge density noise spectrum. For the photon scattering noise spectrum, we apply the Green's function method with a Gaussian rough surface correlation. We find that the charge density noise source is prevalent throughout the entire operation frequency regime. The photon scattering noise is larger for the pump beam when compared to the probe beam often used in experimental setups. We also find that noise spectrum does not change when changing the roughness correlation length. This leads to the experimental setup being very important for reducing noise from photon scattering. With these two noise sources, as well as noise sources derived from electric and magnetic field fluctuations in our previous works, we calculate the change in T2 decoherence time. This relation allowed us to determine the change in decoherence time from each noise source and compare. |
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N01.00095: QED radiative corrections to E1 transition amplitudes in heavy atoms Carter Fairhall, Benjamin M Roberts, Jacinda Ginges Atomic many-body theory has reached the level of precision where account of quantum electrodynamics (QED) radiative corrections is important in the determination of heavy atom properties. The radiative potential method is used to carry out a detailed study of QED corrections to electric dipole (E1) transition amplitudes in alkali-metal atoms Rb, Cs, and Fr, and alkali-metal-like ions Sr+, Ba+, and Ra+. The validity of the method is checked by comparing against the results of rigorous QED. We study the influence of the many-body effects core relaxation, polarization of the core by the E1 field, and valence-core correlations on the QED corrections. Several transitions are identified where the QED contributions exceed the deviation between atomic theory and experiment. |
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N01.00096: Experimental Upgrades For Improving Statistical And Systematic Uncertainties In ACME III Peiran Hu, Zhen Han, Collin Diver, Maya Watts, Daniel G Ang, David DeMille, John M Doyle, Gerald Gabrielse, Ayami Hiramoto, Nicholas R Hutzler, Daniel D Lascar, Zack Lasner, Siyuan Liu, Takahiko Masuda, Cole Meisenhelder, John Mitchell, Cristian D Panda, Noboru Sasao, Satoshi Uetake, Xing Wu, Koji Yoshimura The measurement of the electron electric dipole moment (eEDM), de, is a powerful probe of physics beyond the Standard Model. The current most stringent limit of |de|<1.1 × 10-29 e·cm was reported by the ACME II experiment (Nature, 562(2018), 355). ACME III aims to improve this experimental limit by an order of magnitude. Progress has been made in improving the statistical sensitivity. An electrostatic lens that can increase the flux of a ThO molecular beam has been built and tested. We are also upgrading our fluorescence detectors to silicon photomultipliers for higher quantum efficiency. An upgraded cryogenic buffer gas beam (CBGB) source featuring shorter cool-down time and in-situ target changing function is built for increasing the duty cycle of the experiment. Guided by our recent H 3Δ1 lifetime measurement, a longer interaction region is constructed. We also made progress toward reducing systematic errors and their uncertainty. One significant source of systematic error comes from birefringence gradients in the laser optics. We are implementing a modified measurement scheme to reduce this systematic error and taking several new measures to reduce birefringence gradients. Last, we are building and testing an upgraded magnetic shielding and field control system. |
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N01.00097: QUANTUM INFORMATION SCIENCE
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N01.00098: Temperature and spin-state dependence of phonon-limited spin relaxation for nitrogen-vacancy centers in diamond Matthew C Cambria, Ariel Norambuena, Hossein Dinani, Aedan Robert H Gardill, Ishita Kemeny, Yanfei Li, Vincenzo Lordi, Adam Gali, Jeronimo R Maze, Shimon Kolkowitz Phonon-induced relaxation of the nitrogen-vacancy (NV) center's ground-state electronic spin triplet places hard limits on its performance in many proposed quantum applications. We report experimental measurements of the relaxation rates on both the ms=-1 ↔ ms=+1 qutrit transition and the ms=0 ↔ ms=±1 qubit transition as functions of temperature from 5 to 475 K in high-purity samples, where relaxation is dominated by spin-phonon interactions. We determine the upper limits imposed on NV spin coherence by spin-phonon relaxation over the temperature range relevant for almost all NV applications, and discuss their implications. We analyze the processes responsible for the observed relaxation, finding that two-phonon Raman scattering of quasilocalized phonons with a range of energies surrounding a 72(2) meV vibrational resonance drives relaxation on the qutrit transition approximately twice as fast as on the qubit transition. In addition, we find that a T5 term contributes to the temperature dependence of the relaxation rates on both transitions with equal magnitude, suggesting that the current understanding of the role of acoustic phonons in NV spin-phonon relaxation is incomplete. Part of this work was performed under the auspices of US DOE by LLNL under Contract DE-AC52-07NA27344. |
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N01.00099: Optical tweezer experiments at Los Alamos National Laboratory Leonardo de Melo, thomas bersano, eric meier, Hari Lamsal, andrew harter, Anupam Mitra, sivaprasad T Omanakuttan, Ivan H Deutsch, Michael J Martin We present recent work with optical tweezer experiments for quantum simulation, computation and sensing. The systems are based on Rb-87 and Sr-87 atoms, with the goal of enabling new capabilities through laser-dressing. These include creating entangled states for sensing and manipulating the ten-dimensional nuclear spin manifold in Sr-87. |
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N01.00100: Strain Sensing Using a Single Silicon Vacancy Center in a Diamond Cantilever Sophie Weiyi Ding, Benjamin Pingault, Marko Loncar The silicon vacancy center (SiV) in diamond is studied because of its good optical properties which allows for quantum information applications. The SiV spin also has a high strain susceptibility, 4 orders of magnitude larger than that of the NV ground state. Here we investigate the interaction of a mechanical resonator, consisting of a diamond cantilever, and a single SiV spin embedded in it. We explore the potential of this platform for strain sensing as well as quantum information processing. The long lifetime of the cantilever, around 200 ms at 4K, with fiber coupling for optical access, also offers opportunities in quantum information for mechanical memory coupled to an SiV, which has been studied as a memory node for a quantum network. |
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N01.00101: Trapped ion entanglement gates made robust to Rabi frequency fluctuations via motional squeezing Yotam Shapira, Sapir Cohen, Ady Stern, Roee Ozeri Trapped ion qubits are a leading quantum computing platform. As part of an effort to scale-up the quantum register while maintaining high-fidelity operations, there has been a recent focus on generation of robust quantum operations, specifically robust entanglement gates. |
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N01.00102: Quantum Optimization of Maximum Independent Set using Rydberg Atom Arrays Sepehr Ebadi, Alexander Keesling, Madelyn Cain, Tout T Wang, Harry Levine, Dolev Bluvstein, Giulia Semeghini, Ahmed Omran, Jin-Guo Liu, Rhine Samajdar, Xiu-Zhe Luo, Beatrice Nash, Xun Gao, Boaz Barak, Edward Farhi, Subir Sachdev, Nathan Gemelke, Leo Zhou, Soonwon Choi, Hannes Pichler, Sheng-Tao Wang, Markus Greiner, Vladan Vuletic, Mikhail Lukin Realizing quantum speedup for solving practically relevant, computationally hard problems is a central challenge in quantum information science. Using Rydberg atom arrays composed of up to 289 coupled qubits in two spatial dimensions, we experimentally investigate quantum optimization algorithms for solving the Maximum Independent Set problem. We use a hardware-efficient encoding associated with Rydberg blockade, realize closed-loop optimization to test several variational algorithms, and subsequently apply them to systematically explore a class of nonplanar graphs with programmable connectivity. We find that the problem's hardness is controlled by the solution degeneracy and the number of local minima, and experimentally benchmark the quantum algorithm's performance against optimized classical simulated annealing. On the hardest instances, we observe a superlinear quantum speedup in finding exact solutions for sufficiently long evolution times beyond the shallow-circuit-depth regime, and analyze its origins. |
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N01.00103: Universal quantum gate operations in an array of 171Yb nuclear spin qubits Alex Burgers, Shuo Ma, Genyue Liu, Jack Wilson, Bichen Zhang, Miguel Alarcon, Chris H Greene, Jeff D Thompson Rydberg-mediated entanglement between neutral atoms in optical tweezer arrays is a rapidly developing platform for quantum science. An emerging frontier within this field is the use of alkaline earth-like atoms (AEAs) such as ytterbium (Yb). The rich internal structure of these atoms affords numerous unique capabilities, including narrow-line cooling and imaging [1], an optically active ion core for Rydberg state trapping [2] and gate addressing [3], and, in fermionic isotopes, highly coherent qubit storage in the nuclear spin. In this poster we present our recent demonstration and characterization of a universal set of quantum gate operations on a qubit in the I=½ nucleus of 171Yb [4]. We will also discuss ongoing work to encode qubits in the metastable 3P0 state, which may yield better two-qubit gate fidelities and have advantages for quantum error correction based on “erasure conversion” [5]. |
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N01.00104: Quantum search by the nonlinear Schrodinger equation with a generalized cubic-quintic nonlinearity Benjamin D DalFavero, Alexander Meill, David Meyer, Thomas Wong, Jonathan P Wrubel Continuous-time quantum walks, a quantum analog to the continuous-time |
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N01.00105: Demonstration of a simplified projected optical trap array Preston Huft, Yunheung Song, Kais Jooya, Trent Graham, Sanket Deshpande, Chengyu Fang, Mikhail A Kats, Mark Saffman Arrays of optical traps are ubiquitous in cold atom experiments, including quantum computing and quantum simulation, due to their stability and versatility. However, the optical setups for creating these traps are often complicated, space-consuming, and expensive, requiring active electro-optical devices. Here we present an approach for trapping cold atoms in a 2D optical trap array generated with a novel 4f filtering scheme and custom transmission mask without any active device. The approach can be used to generate arrays of bright or dark traps, or both simultaneously in customizable configurations. Using blue-detuned light, we demonstrate loading of single Cs atoms in 2D trap arrays with up to 1225 sites. Moreover, we demonstrate a simple solution to the problem of out-of-focus trapped atoms, which occurs due to the Talbot effect in periodic optical lattices. In such cases, atoms trapped out-of-focus lead to higher background in fluorescence measurements, complicating single atom imaging and control. By using a relatively inexpensive spectrally and spatially broadband laser, out-of-focus interference is mitigated, leading to near perfect removal of Talbot plane traps and improved SNR during fluorescence readout. |
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N01.00106: Programmable quantum circuits with arrays of nuclear spins William Huie, Lintao Li, Neville Chen, Brett N Merriman, Mingkun Zhao, Ian Vetter, Jacob Covey Neutral atom arrays with Rydberg-mediated interactions have become a promising platform for quantum science applications. Alkaline earth(-like) atom (AEA) arrays have expanded the neutral atom toolbox by offering new techniques for the control of Rydberg states and opportunities for metrology, leveraging unique ultra-narrow optical "clock" transitions and isolated nuclear spins. This poster will present our analysis of the Rydberg-based omg architecture for 171Yb nuclear spins, which offer optical (o), ground (g), and metastable (m) qubits, all within a single atom. We additionally offer experimental progress and outlook toward the use of 171Yb for quantum computing and networking applications. |
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N01.00107: Universal Single Qutrit Gate in Ultracold 87Rb Joseph Lindon, Arina Tashchilina, Logan W Cooke, Nicholas Milson, Lindsay J LeBlanc Compared to a qubit processor with an equivalent number of interconnected qudits, a qutrit processor has access to a larger computational Hilbert space, and thus can solve more complex problems. A single qutrit can be used to demonstrate quantum speedup, contains double the information of a single qubit, and unlike the qubit it has no classical analog. Favourably, a third eigenstate is available for quantum computation in systems that are conventionally used for qubits, among those are photonic and superconducting circuits, trapped ions, NV centers, and neutral atoms. |
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N01.00108: Implementing Molecular Quantum Logic in a Cryogenic Ion Trap Grant D Mitts, Clayton Z Ho, Hao Wu, Eric R Hudson The structure of dipolar molecular ions provides new inroads to quantum logic that do not require lasers. As such, these operations are not impaired by the usual spontaneous scattering and do not require motional ground-state cooling typical of trapped atomic ions. We will present calculations regarding the application of dipole-phonon quantum logic (Phys. Chem. Chem. Phys., 2020, 22, 24964-24973) and electric-field gradient gates (PhysRevA. 2021, 104, 042605) to trapped molecular ions with an eye towards robust quantum logic operations with high fidelity. We will also describe a recently constructed cryogenic ion trap system for exploring these operations. |
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N01.00109: Solving Linear Systems of Equations on a Trapped Ion Quantum Computer Elijah Mossman, Navdeep Singh, Nhung H Nguyen, Alaina Green, Yingyue Zhu, Norbert M Linke Solutions to linear systems of equations are the key to many technologically relevant applications, including artificial intelligence, data processing, and system modeling. The Harrow-Hassidim-Lloyd (HHL) quantum algorithm has been shown to provide exponential speed-up over classical methods for solving these systems [1]. Here we present the results of an experimental demonstration of the HHL algorithm on a trapped ion quantum computer. We develop an optimized, 4-qubit circuit to correctly solve a system of two and four equations. The process fidelity of our trapped ion quantum computer is high enough to accurately identify the solution without the use of error mitigation. |
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N01.00110: Progress towards an efficient quantum network with rubidium atoms Akbar Safari, Christopher B Young, Preston Huft, Jin Zhang, Eunji Oh, Ravi Chinnarasu, Mark Saffman Achieving an efficient quantum link between multiple quantum processors is a challenging task |
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N01.00111: Experimental platform for a 2D atom array quantum computer with non-destructive readout Trent Graham, Yunheung Song, Jacob Scott, Kais Jooya, Linipun Phuttitarn, Cody Poole, Matthew Gillette, Mark Saffman We present an experimental platform for a 2D neutral Cs atom array quantum computer. Atoms are loaded into a 2D array of optical traps created using two orthogonal sets of blue-detuned tophat lines. Lambda grey molasses is used to cool atoms in traps to below 5 microKelvin. To determine the array occupation, atom fluorescence is collected by two 0.7 NA lenses at the front and back of the cell and imaged onto an EMCCD. A red-detuned tweezer is then used to rearrange atoms in the lattice to a desired pattern for a quantum computation. For our universal gate set, single qubit rotations are performed using a combination of global microwaves and site-selective Stark shift lasers; two qubit controlled-phase gates are implemented using two photon Rydberg excitation. For each Rydberg laser, two independent pairs of AODs allow for simultaneous atom addressing. |
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N01.00112: Ytterbium 171 optical tweezer arrays for quantum information and metrology Aruku Senoo, William F McGrew, Joanna W Lis, Alec Jenkins, Adam M Kaufman Neutral atoms in optical tweezer arrays are a promising platform for quantum computation, simulation and metrology. Previous tweezer systems have mainly focused on alkali atoms and bosonic alkaline earth(-like) atoms because of their relatively simple atomic structures. Here, we present a new optical tweezer array platform with 171Yb, a fermionic alkaline earth-like atom with nuclear spin 1/2. The naturally two-level nuclear spin qubit benefits from long coherence times in both the ground electronic state (1S0) and metastable clock state (3P0). This structure will enable projective measurement of certain qubits while preserving the quantum information stored in other qubits, a prerequisite for many quantum error correction protocols as well as enhanced optical clock interrogation schemes. The clock state can also be excited to a Rydberg state by a single-photon transition, enabling fast two-qubit gates and allowing for highly coherent quantum simulation. Towards these goals, here we report scalable, near-deterministic single-atom preparation and detection of 171Yb arrays and demonstrate high-fidelity, sub-microsecond-scale manipulation of the nuclear spin qubit with seconds-scale coherence times. We further describe our progress towards the realization of mid-circuit measurement as well as Rydberg-based two-qubit gates and quantum simulations. |
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N01.00113: A dual-element, two-dimensional atom array with continuous-mode operation Kevin Singh, Shraddha Anand, Ryan White, Vikram Ramesh, Hannes Bernien Quantum processing architectures that include multiple qubit modalities offer innovative strategies for high-fidelity qubit manipulation and readout, quantum error correction, and a path for scaling to large system sizes. We present a programmable quantum device based on a dual-element neutral atom array composed of Rb and Cs atomic qubits in up to 512 trapping sites [1]. Our observation of negligible crosstalk between the elements enables a new continuous mode of operation for atom arrays without any off-time. We report recent progress towards inter-element Rydberg gates and describe avenues for mediated multi-qubit gates, efficient production of large-scale entanglement, and ancilla-assisted quantum protocols such as QND measurements and quantum error correction. |
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N01.00114: An Efficient Method for Cluster State Construction based on Counterfactual Carving in an Optical Cavity Luke M Stewart, Joshua Ramette, Josiah J Sinclair, Vladan Vuletic We show how counterfactual carving, a recently developed theoretical proposal to produce high fidelity, multipartite entanglement, could be applied to generate fully-connected resource states for measurement-based quantum computing. For a neutral atom ensemble in an optical cavity, the cavity mode spectrum is shifted differently by each Dicke state of the collective spin. A "source" atom illuminated with multiple tones tuned near resonances of the cavity mode spectrum imparts unique amplitude and phase shifts to the Dicke states dependent on tone strengths and detunings. We develop a simple prescription of tones that produces fully-connected graph states of resource qubits, which can be efficiently merged into cluster states for universal quantum computation. Importantly, the ability to carve many-body entanglement enables resource state creation in a single cavity operation, eliminating the need for the time-consuming, low success probability two-qubit operations typically used to generate the resource state. |
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N01.00115: Holonomic Quantum Computing in Ultracold Neutral Atoms via Floquet Engineering Logan W Cooke, Arina Tashchilina, Joseph Lindon, Tian Ooi, Taras Hrushevskyi, Lindsay J LeBlanc Holonomic quantum computing (QC) aims to be an intrinsically fault-tolerant alternative to conventional QC techniques; it utilizes non-Abelian geometric phases in highly degenerate systems to realize universal unitary transformations of states in the manifold. While there have been many successful implementations, a scalable platform remains elusive in large part because of the required degeneracy; recently, several proposals have shown that Floquet-engineering may be used to surpass this issue. We demonstrate this concept in a BEC of Floquet-engineered rubidium-87 atoms, where fast periodic driving results in the required degeneracies between atomic spin states and their subsequent holonomic evolution. In particular, we utilize Wilson loops to show that the geometric phase is non-Abelian in a fully gauge-invariant manner; this is required for the protocol to be truly holonomic. Our results for spin-1 transformations are shown along with numerical simulations, and we discuss the protocol's efficacy as a real-world QC model. |
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N01.00116: Realizing a quantum register using collective excitations in an atomic ensemble without a Rydberg blockade Elisha B Haber, Zekai Chen, Nicholas P Bigelow A qubit made up of an ensemble of atoms is attractive due to its resistance to atom losses and is usually achieved using the Rydberg blockade effect. In this work, we consider a protocol to load a spin-dependent optical lattice with one atom per site from a spatially overlapping atomic ensemble without using any transitions out of the 87Rb F=1 ground state manifold. This is achieved using a radiofrequency pulse to drive a transition between Zeeman sublevels, and a blockade effect that arises from the strong s-wave interaction between atoms in the same lattice site. Identifying each lattice site as a qubit, we demonstrate how qubit operations that are insensitive to the size of the ensemble may be performed, and how two qubits may be entangled using the ensemble. |
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N01.00117: Realizing coherently convertible dual-type qubits with the same ion species Jianyu Ma, Haoxiang Yang, Yukai Wu, Ye Wang, Mingming Cao, Weixuan Guo, Yuanyuan Huang, Lu Feng, Zichao Zhou, Luming Duan For large-scale ion-trap based quantum computers and networks, it is critical to have two types of qubits, one for computation and storage, while the other for auxiliary operations like runtime qubit detection, sympathetic cooling, et al. Dual-type qubits have previously been realized in hybrid systems using two ion species, which, however, introduces significant experimental challenges for laser setup, gate operations as well as the control of the fraction and positioning of each qubit type within an ion crystal. Here we solve these problems by implementing two coherently-convertible qubit types using the same ion species. We encode the qubits into two pairs of clock states of the 171Yb+ ions, and achieve fast and high-fidelity (about 99.5%) conversion between the two types using narrow-band lasers. We further demonstrate that operations on one qubit type, including sympathetic cooling, gates and qubit detection, have crosstalk errors less than 0.06% on the other type. |
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N01.00118: STRUCTURE AND PROPERTIES OF ATOMS, IONS, MOLECULES, AND PLASMAS
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N01.00119: Alkali-Metal Spin-Destruction Rates in Rb-Xe and Cs-Xe Systems Zahra Armanfard, Adnan Nahlawi, Brian T Saam We measure and compare the spin-destruction rates for Rb and Cs in a He(94%)-N2(3%)-Xe(3%) gas mixture. The measurements are crucial to understanding which alkali-metal is the most efficient for polarizing 129Xe and are carried out in two matched sets (one each for Rb and Cs) of four sealed vapor cells, allowing us to determine the respective spin-destruction rates as a function of total gas density at fixed composition. Optically detected pulsed EPR is used to observe the slowest polarization-decay component of the alkali-metal atoms in the dark. We measure a Xe-Cs rate about 20% slower than that of Xe-Rb over the density range of one to a few amagats. Spin destruction in this range is dominated by binary collisions with Xe and very-short -lifetime Rb-Xe or Cs-Xe van der Waals molecules. Our Rb data are consistent with Nelson and Walker’s results and corresponding theoretical model [1], which we have also adapted to interpret our Xe-Cs data. Considering the reported 10% faster spin-exchange rate coefficient for Cs-Xe [2], we estimate a ≈40% improvement in Cs SEOP efficiency vs. Rb. We are currently attempting to verify this estimate with our own spin-exchange rate-coefficient measurements for these same cells. |
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N01.00120: Frequency comb measurements of Ca Rydberg states and the Ca ionization energy Scott D Bergeson, CHAN HYUN PAK, Mason Christiansen, Joseph Buck, Matthew Schlitters A recent publication by Zelener [Jetp Lett. 110, 761 (2019)] reported transition frequency measurements in Ca from the 4s2 1S0 ground state to 4sns 1S0 states with n=40-120. The Ca atoms were trapped in a MOT. Excitation was detected using trap loss spectroscopy. While the Doppler effect was minimized in the MOT environment, systematic density-dependent shifts remained. The published lineshapes were asymmetric and far from Lorentzian. Furthermore, frequency measurements were referenced to a commercial wavelength meter. We report new frequency-comb-based measurements of these transitions using atoms in an atomic beam. A two-photon Doppler-reduced method is used to excite 4sns 1S0 states using cw lasers at 423 and 390 nm. The resulting lineshapes are symmetric and Lorentzian. Verification of both laser metrology and absolute accuracy are verified by reproducing measurements of well-known transitions in Cs and Rb, close to the fundamental wavelengths of our frequency-doubled ti:sapphire lasers. From the measured transition energies we derive the ionization energy of Ca. |
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N01.00121: Revisiting Iodine molecule: Laser spectroscopy in the 14600-14710 cm-1 range. Manuel A Lefran Torres, Marcos R Cardoso, David Rodriguez Fernandez, Luis Gustavo Marcassa In this work, we report the laser absorption spectroscopy of iodine gas in the range of 14600 to 14710 cm-1. This wavelength range is scanned using a narrow linewidth diode-laser whose frequency is actively measured using a calibrated wavelength meter. This allows us to provide an iodine atlas that contains almost 729 experimentally observed reference lines. For most lines, good agreement is found with a publication by Houssam Salami and Amanda J. Ross (2005), but we have observed new lines due to the high resolution of our laser. The new dataset can be useful as a reference for laser frequency calibration and stabilization. |
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N01.00122: Neutral Ti for an atomic clock Dmytro Filin, Charles Cheung, Sergey G Porsev, Dan Stamper-Kurn, Scott Eustice, Jackson Schrott, Diego Diego, Yubin Hu, Lely Tran, Marianna Safronova Titanium is a candidate for laser cooling and has possible clock transitions in the telecom wavelength range. We carry out extensive calculations of energies, transition rates, lifetimes, branching ratios, and polarizabilities of neutral Ti to explore its potential for a development of an optical frequency standard. Titanium has four valence electrons and its electronic correlations are difficult to describe accurately. In this work, we use the CI+all-order method for that combines linearized coupled-cluster and configuration interaction (CI) approaches. We calculate transition rates and branching ratios for potential laser cooling and clock transitions. Ten forbidden transitions between the first 5 low lying even levels of neutral Ti are considered. Magnetic-dipole (M1) and electric-quadrupole (E2) reduced matrix elements were obtained in the random-phase approximation (RPA). For the potential clock transition from 3d3(4F)4s 5F1 level to the ground state 3d24s2 3F2 blackbody radiation (BBR) shift was also calculated. Good agreement between the experimental and computed energy levels and Lande g-factors confirms the fidelity of the obtained results and the accuracy of the CI+All-order method for Ti. |
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N01.00123: Laser Induced Fluorescence Spectroscopy of the Rb 5S - 6S One-Photon M1 Transition Mark D Lindsay, Carson D McLaughlin, Randy J Knize Using a collimated Rb atomic beam and locking a microwave-driven EOM sideband of our 497 nm laser to an ultrastable very high finesse optical cavity, thus tuning the laser with microwave frequency accuracy, we have conducted one-photon LIF spectroscopy of the Rb 5S - 6S transition, in both isotopes. We are in the process of measuring for the first time the M1 transition amplitude to, and the atomic scalar and vector polarizabilities α and β of, the Rb 6S state. The M1 transition amplitude has implications for detecting the Dirac Negative Energy States of Rb. |
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N01.00124: Hyperfine Splittings and Isotope Shift of the Rb 5S - 6S Two-Photon Transition Carson D McLaughlin, Rajani Ayachitula, Mark D Lindsay, Randy J Knize Using a Rb vapor cell and locking a microwave-driven EOM sideband of our 993 nm laser to an ultrastable very high finesse optical cavity, thus tuning the laser with microwave frequency accuracy, we have conducted Doppler free two-photon spectroscopy of the Rb 5S - 6S transition, in both isotopes. We have measured the hyperfine splittings of the 6S state, and the isotope shift of the transition, to an accuracy of about 10 kHz. |
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N01.00125: Identification of Iridium I and II Lines from a Hollow Cathode Lamp Brynna Neff, Steven Bromley, Brandon Martin, Mike Fogle, Stuart Loch, Joan Marler The observation of neutron star mergers has highlighted the importance of heavy metals such as iridium in astrophysics. However, more experimental work is still necessary to have a thorough understanding of the electronic structure of iridium. To this end, we collect spectra emitted between 200 and 1500 nm from a Hollow Cathode lamp in order to identify both new and previously observed lines of Iridium I and II. We analyze the line intensities to determine their dependence on the current applied to the lamp as well as the relative intensities of lines with the same upper energy level. |
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N01.00126: Towards an optogalvanic flux sensor for nitric oxide based on Rydberg excitations Philipp Neufeld, Fabian Munkes, Patrick Kaspar, Yannick Schellander, Lars Baumgärtner, Lea Ebel, Jens Anders, Edward R Grant, Robert Loew, Tilman Pfau, Harald Kuebler We demonstrate the applicability of a new kind of gas sensor based on Rydberg excitations. From a gas mixture the molecule in question is excited to a Rydberg state. By succeeding collisions with all other gas components this molecule becomes ionized and the emerging electrons can be measured as a current. We investigate the excitation efficiency dependent on the used laser powers, the applied charge-extraction voltage as well as the overall gas pressure. |
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N01.00127: Laser Spectroscopy of MgF Kayla J Rodriguez, Stephen Eckel, Eric Norrgard
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N01.00128: Nonadiabatic decay of metastable states on coupled linear potentials Ansh N Shah, Alisher Duspayev, Georg A Raithel
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N01.00129: Progress toward precise determination of atomic lifetimes using photon echoes Thomas Vacheresse, Gehrig M Carlse, Alexander Pouliot, Hermina C Beica, Louis Marmet, A Kumarakrishnan We review the progress of a photon echo experiment for sensitive measurements of atomic lifetimes. Using short-pulse excitation of atomic rubidium vapor, we have recently reported the most statistically precise measurement of (26.11 ± 0.03) ns for the 52 P3/2 lifetime*. The experiment relies on heterodyne detection and exploits the signal-to-noise ratio of the coherent release of energy along the direction of excitation, which is an exponential decay as a function of pulse separation T, as well as large repetition rates that are feasible in a heated vapor cell. We describe a background subtraction technique for simultaneously recording signal and background pulses at repetition rates of 1MHz. We expect this technique to overcome technical limitations and allow the exploration of systematic effects. |
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N01.00130: Rovibrationally resolved lifetime of the 6sSg(v=40,J) state molecular sodium Burcin S Bayram, Sanjib Thapa, Shakil M Bin Kashem, Morgan Davies Alkali molecules and investigations of their structures and dynamics of short range interactions are important for ultracold molecular physics. This is because ultracold molecules have been used to probe new states of quantum matter, molecule lasers, and to improve precision measurements of fundamental constants. Due to the exotic behavior of the 6sSg(3s+5s) symmetry with double well structure, studying the radiative properties of this state becomes especially important. This work deals with the experimental and and theoretical studies of the 6sSg(v=40, J=23-25) state of sodium diatomic molecules in collaboration with Professors Ashman of Providence College and Faust of Susquehanna University. We used two-step double resonance technique for excitation and photon-counting technique for detection. Molecules are resonantly excited from the two pulsed lasers at 574.54 nm and 561.67 nm to follow XsSg(7,23) - AsSu(37,24) - 6sSg(40,23) excitation channel. Spectrometer is used as a filter to select specific molecular fluorescence peak, then the peak was directed to the pmt-multichannel analyzer to measure the 6sSg(40,23) state lifetime. |
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N01.00131: Suppression of Raman interaction due to destructive interference in alkali atoms Arina Tashchilina, Evgeny Moiseev, Logan W Cooke, Joseph Lindon, Lindsay J LeBlanc Raman interactions are a powerful tool for performing arbitrary rotations between two Zeeman levels of an individual ion or a neutral atom. Universality of the technique places it on central roles in many quantum technologies: single qubit gates in atomic quantum processors, mediating interactions in quantum simulators, and mapping quantum information into long-lived states in optical quantum memories, to name a few. |
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N01.00132: Measuring the hyperfine splitting of rubidium 5P$_{1/2}$ excited-state using Saturated Absorption Spectroscopy Priyanka M Rupasinghe, Fiona Wee, Thomas Bullock, Jiaxing Liu The Saturated Absorption Spectroscopy (SAS) was performed to measure the hyperfine energy splittings of rubidium 5P$_{1/2}$ excited state using a homemade external-cavity diode laser (ECDL) operating at 795 nm. Any nonlinearities associated with ECDL scans were removed by using a low-expansion confocal Fabry-Perot cavity and hence created a linearized frequency axis for the spectra collected in a fully automated fashion. Our results will be compared with the previous measurements reported in the literature. |
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N01.00133: Lifetime study of cubic Rb vapor cell with Al2O3 coating through light induced atomic desorption JiHoon Yoon, Sangkyung Lee, Sin Hyuk Yim Lifetime of Rb vapor cell with Al2O3 coating was studied by light induced atomic desorption(LIAD). By observing variation of Rb vapor density due to LIAD, we measured characteristic parameters describing LIAD of our cubic cells. The model describing LIAD includes irreversible absorption of free Rb atoms inside the coating. We studied the dependency of irreversible absorption rate on coating, temperature and buffer gas pressure. At the same time, the density variation of free Rb atoms inside the coating was calculated by LIAD model. Taken together, the cell lifetime was estimated with given initial amount of Rb atoms. |
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N01.00134: ULTRAFAST AND STRONG FIELD PHYSICS
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N01.00135: Covariance Velocity Map Imaging Measurements of Strong Field Double Ionization Chuan Cheng, Vaibhav Singh, Spiridoula C Matsika, Thomas Weinacht Double ionization has been of long outstanding interest as a probe of electron correlation in molecules exposed to strong laser fields. However, state resolved measurements of the double ionization yield have been quite elusive. Recently, progress has been made on both single photon and strong field state resolved double ionization on water molecule. Here we have extended our experiment to more complicated molecular structures such as deuterated formaldehyde (CD2O). We doubly ionize the molecules with pulses over a range of pulse energies and durations (5-30 fs, 44 TW/cm2 - 240 TW/cm2 ). We measure the full 3D momentum of the fragments using velocity map imaging and a Timepix camera, and we make use of covariance analysis to separate different dissociation channels. By performing trajectory surface hopping (TSH) calculations on the low lying states of the dication, we can determine the kinetic energy release (KER) of fragments associated with each state of the dication. Fitting the measured KERs for different dissociation channels allows us to determine the relative population of the different dication states produced by the strong field double ionization. We find that the populations do not vary monotonically with energy. |
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N01.00136: Two-path interference in the resonance-enhanced few-photon ionization of lithium atoms Nicolas Douguet, Bishnu P Acharya, Santwana Dubey, K. L. Romans, A.H.N.C. De Silva De Silva, Kyle Foster, Onyx Russ, Klaus R Bartschat, Daniel Fischer We investigate the resonance-enhanced few-photon ionization of an atomic Li target at a photon energy near the resonance between the 2s ground and 2p excited states. For this system, the ground-state ionization resembles an atomic “double slit”, because it can proceed through the 2p resonances with the magnetic quantum number m being either −1 or +1. In our experiment, the target can be prepared in one of the polarized excited 2p states before subjecting it to the ionizing radiation, thereby effectively closing one of the two slits. This procedure makes it possible to extract the interference term between the two pathways to obtain complex phase information on the final state. The analysis of our experimental results is supported by an ab initio model based on the numerical solution of the time-dependent Schroedinger equation. |
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N01.00137: Investigating strong-field induced rotational coherences in the cationic states of oxygen using UV pulses and high-resolution FFT spectroscopy Huynh Van Sa V Lam, Tomthin Nganba Wangjam, Vinod Kumarappan We investigate the bound wave packet populated by an intense 800-nm pulse in low-lying cationic states of oxygen. This wave packet is probed using dissociation by a UV pulse. The delay-dependent momentum distribution of O+ is Fourier transformed to obtain kinetic-energy-dependent and rotational-state-resolved quantum beat spectra. The Fourier spectrum shows dominant signature of wave packets in b4Σ_{g}^{_} and the X2Πg states. The similarity in appearance of the b4Σ_{g}^{_} state quantum beat spectra compared to the case of a weak 800 nm probe confirms the resonant coupling between b4Σ_{g}^{_} and a4Πg induced by the 800 nm pump. The dominance of the X2Πg(v=3) state, on the other hand, shows the importance of resonant coupling in the UV probe pulse. Rotational coherence in the X2Πg state also shows correlation between rotational and electronic dynamics via spin-orbit coupling. |
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N01.00138: Analysis of strong-field ionization via a Bohmian Mechanics approach Taylor Moon, Klaus R Bartschat, Nicolas Douguet We employ Bohmian Mechanics to investigate the strong-field ionization of atomic hydrogen in an ultrashort infrared pulse. The streamlines of the probability current are computed and allow us to obtain quantum trajectories providing insights into the strong-field ionization process. In particular, we study the transition from the multi-photon to the tunneling regime and interpret the main features of the asymptotic electron momentum distribution. |
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N01.00139: Modeling molecular break-up processes under short and intense laser pulses Chi-Hong Isaac Yuen, Paresh Modak, C.D. Lin Intense short laser pulses (a few femtoseconds) have been used in recent years to study the breakup dynamics of molecules. |
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N01.00140: Ambiguity Removal of Two-Color SHG-FROG Traces by Time Seperation Mark Schittenhelm, Rana Jafari, George N Gibson, Rick Trebino, Soroush Khosravi The complete temporal characterization of two-color ultrashort pulses is important for many applications, especially the study of ultrafast events and generation of high-order harmonics in the soft x-ray and extreme ultraviolet regions. While Second-Harmonic Generation (SHG) Frequency-Resolved Optical‑Gating (FROG) has proven to be a powerful and reliable technique for precisely measuring even complex pulses, it (and all other known self-referenced techniques) suffer from an inherent relative-phase ambiguity for two-color pulses and so will not provide complete information about the pulse total electric field in some cases. In this work, we demonstrate that such ambiguities in SHG FROG measurements can be eliminated by separating the components (colors) of the two-color pulse in time. We find that the ability to remove this ambiguity in SHG-FROG strongly depends on the pulse separation, as well as the pulse durations. The dependence of the rms difference between the actual and ambiguous SHG-FROG traces on pulse separation exhibits an oscillatory behavior and is non-zero (that is, the ambiguity is removed) only for a certain range of separations. We demonstrate this behavior for multi-cycle and few-cycle pulses. |
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N01.00141: Application of a wavelength-independent autocorrelator for characterization of sub-100 femtosecond UV pulses from an OPA John Searles, Zane Phelps, Anbu S Venkatachalam, Surjendu Bhattacharyya, Huynh Van Sa V Lam, Catherine Mikhailova, Artem Rudenko, Daniel Rolles The tunable output in the UV and DUV region from an optical parametric amplifier (OPA) is used to perform multicolor pump-probe experiments. For this purpose, the OPA output pulses are compressed by a prism compressor. We demonstrate a FROG-type autocorrelator, based on two-photon absorption in a thin crystal, to characterize the compressed sub-100 femtosecond UV and DUV pulses over a broad wavelength region. |
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N01.00142: Atomic Rydberg ionization dynamics out of an optical dipole trap Daniel Fischer, Kevin L Romans Cold-target recoil ion momentum spectroscopy (COLTRIMS) with optically cooled and trapped atomic targets has proven to be a very powerful tool to study atomic ionization dynamics in great detail and with high resolution. Here we investigate how the trapping field of a far-off resonance optical dipole trap can affect such experiments. Specifically, the break-up of optically trapped lithium atoms is observed, which are excited in a femtosecond laser pulse and subsequently ionized in the field of a near-infrared continuous-wave trapping laser. We measure the photoelectron angular and energy distributions as well as the time after the arrival of the femtosecond laser pulse at which the ionization takes place. This allows studying the effect of the trapping laser field on the atomic dynamics and provides information on the time-dependent population transfer of bound and continuum states. |
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N01.00143: A multi-wave mixing study investigating electronic coupling of dark and continuum states in Neon. Islam S Shalaby, Sergio Yanez-Pagans, Nisnat Chakraborty, Arvinder S Sandhu Ultrafast non-linear mixing techniques have been recently extended to the extreme-ultraviolet (XUV) regime which made it possible to probe quantum states and their light-induced couplings. Using transient absorption spectroscopy, we observe electronic couplings between the Rydberg and continuum states around the ionization potential of neutral Neon, as well as couplings to the dark states of Neon involving four and six wave mixing processes. Moreover, we observe long-lived coherent beats involving the spin-orbit split dark states, which form interfering pathways in the multi-wave mixing processes. The photon energy tunability and time-delay of the near-infrared (NIR) probe pulse are used to control the contributions of the different pathways and investigate the electronic structure of the excited states of the atom. The strength of various four- and six-wave mixing signals show an interesting and counter intuitive behavior, which is being investigated. |
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N01.00144: Dynamic interference in the 2+1 photon resonance-enhanced multiphoton ionization of Li Attila Tóth, András Csehi Multiphoton excitation and subsequent ionization of atomic systems is a widely studied |
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N01.00145: Long-lasting Orientation induced by Two-Color Femtosecond Laser Pulses Long Xu, Ilia Tutunnikov, Yehiam Prior, Ilya Averbukh Molecular alignment and orientation have attracted considerable interest due to their importance in various applications in physics, chemical reaction, and attosecond electron dynamics. Recently, we reported a new phenomenon of long-lasting orientation in chiral molecules excited by a laser pulse with twisted polarization and in non-linear molecules excited by THz pulses. ‘Long-lasting’ means that the time-averaged orientation remains non-zero on a time scale exceeding the duration of the external fields by several orders of magnitude. Here we show that non-resonant two-color laser pulses consisting of a fundamental wave and its second harmonic are effective for inducing the molecular orientation, and report long-lasting orientation of symmetric- and asymmetric-top molecules following excitation by two-color femtosecond laser pulses. The long-lasting orientation relies on the combined effect of field-polarizability and field-hyperpolarizability interactions. We also study the dependence of the degree of long-lasting orientation on temperature and pulse parameters. The long-lasting orientation can be measured utilizing second (or higher-order) harmonic generation and may be used to control the deflection of molecules traveling through inhomogeneous electrostatic fields. |
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