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 F01: Poster Session I (4:30-6:30pm, EDT)Poster
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Room: Grand Ballroom C |
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F01.00001: GPMFC STUDENT POSTER PRIZE COMPETITION FINALISTS
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F01.00002: Molecular vibrational spectroscopy with 13-digit accuracy Kon H Leung, Brandon Iritani, Emily Tiberi, Tanya Zelevinsky Molecular clocks are a powerful platform in the search for new physics, including yet unknown forces and the time variation of fundamental constants. Previously, we demonstrated magic wavelength trapping of 88Sr2 molecules in a 1D optical lattice, enabling coherence times approaching 100 ms limited by lattice light scattering [1,2]. Here, we present a detailed analysis of the high-Q vibrational clock transition spanning the entire depth of the X1Σg+ ground potential. We demonstrate control of systematic shifts in the molecular clock at the 10-14 level with possibilities for further improvement, and report a measurement of the vibrational splitting with 13-digits accuracy. Additionally, we discuss current efforts toward longer clock interrogation times and larger signal-to-noise through STIRAP [3], rotational repumping, and atomic sideband cooling. |
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F01.00003: Reducing magnetic-field related noise in the ACME III Electron EDM Search Siyuan Liu, John Mitchell The next generation of the ACME Experiment (ACME III) is under development, aiming to measure the electric dipole moment (EDM) of the electron with an unprecedented sensitivity and to probe physics beyond the Standard Model. This upgrade features a longer interaction region to increase the spin precession time, and significantly smaller magnetic-field-related noise. To achieve this, we’re building 3 key systems related to the control of magnetic fields. A custom 3-layer mu-metal magnetic shield covering a larger interaction region is expected to reduce the ambient magnetic field to below , with the help of its optimized geometric design and state-of-the-art degaussing systems. An upgraded self-shielding cosine-theta coil can apply homogeneous fields in the interaction region without magnetizing the shields. A field measurement system, consisting of an array of wide-dynamic-range magneto-resistive sensors and ultra-sensitive optically pumped magnetometers, monitors the field distribution in and around the shields during the experiment, enabling the precise measurement of field gradients and the detailed assessment of systematic uncertainties. |
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F01.00004: Measuring the Gravitational Redshift at the Centimeter-Scale using a Multiplexed Optical Lattice Clock Jonathan C Dolde, Xin Zheng, Hong Ming Lim, Nico Ranabhat, Shimon Kolkowitz Precision tests of general relativity allow for searches of beyond standard model physics at new energy and length scales. In addition, measurements of general relativistic time-dilation with optical atomic clocks have been proposed as a new tool for mapping Earth's gravitational potential with sub-centimeter height resolution. We report progress towards testing the gravitational redshift predicted by general relativity at the centimeter and sub-centimeter scale. We perform synchronous differential measurements between multiple ensembles of ultra-cold neutral 87Sr separated by a centimeter or less in height within a 1D optical lattice. We recently demonstrated a relative fractional frequency uncertainty between two ensembles of 8.9x10-20 in this system, corresponding to a statistical uncertainty of a part in ten of the expected redshift at 1 cm [1]. We present a differential systematics budget summarizing our ongoing evaluation of the differential perturbations to these ensembles at the requisite levels of systematic uncertainty. Finally, we present planned upgrades to improve our multiplexed clock's stability and accuracy. |
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F01.00005: Update of the JILA Gen. II eEDM Experiment Trevor Wright, Tanya Roussy, Luke A Caldwell, Kia Boon Ng, Noah Schlossberger, Sun Yool Park, Anzhou Wang, Benjamin D Hunt, Antonio Vigil, Gus Santaella, Jun Ye, Eric A Cornell Increasingly precise measurements of the permanent electric dipole moment of the electron (eEDM) probe physics beyond the standard model and shed light on open questions such as the baryon asymmetry and dark matter. Our measurement of the eEDM uses a thermal cloud of HfF+ ions held in an RF trap, allowing us to leverage second-scale coherence times and the large internal electric fields present in polar molecules. In this poster I present the final stages of the second generation measurement and discuss key systematic effects in the experiment. |
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F01.00006: Toward vacuum ultraviolet (VUV) dual-comb spectroscopy Yu Zhang, R. Jason Jones Intra-cavity high harmonic generation (iHHG) using a femtosecond enhancement cavity (fsEC) has been proven to be an efficient approach to generate coherent vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) frequency combs. Current VUV or XUV light sources such as synchrotron or excimer lasers either require large facilities or have limited coherence. High resolution measurements in VUV and XUV are of great importance in many areas including tests of fundamental physics, astronomy, as well as in searches for direct excitation of nuclear transitions such as the 229Th M1 isomeric nuclear transition. Direct spectroscopy with a single frequency comb is challenging due to the potential for congestion and overlap of the comb teeth with the transitions of interest. We have pursued a VUV dual-frequency comb system to enable the study of a broader range of atomic and molecular transitions. In this poster, we will show our preliminary results towards the VUV dual-comb utilizing the 3rd (~355 nm) and 5th (213 nm) harmonics from a pair of fsEC's. |
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F01.00007: Directional dark matter detection in diamond: principles and experimental progress Reza Ebadi, Mason C Marshall, David F Phillips, Ronald L Walsworth The next generation of weakly interacting massive particle (WIMP) dark matter (DM) detectors will be sensitive to coherent scattering of solar neutrinos from target nuclei, demanding an efficient background-signal discrimination tool. A directional detector would enable detection of WIMP DM below the "neutrino floor", otherwise an irreducible background. Diamond has been proposed as a next-generation DM detector because of its sensitivity to low-mass WIMP candidates, as well as its excellent semiconductor properties, making it a suitable target for sub-GeV DM detection. We are developing complementary methods for nuclear recoil directionality readout in diamond. WIMP- and neutrino-induced nuclear recoils would leave a sub-micron track of lattice damage, constituting a durable signal for the incoming particle's direction. Spectroscopy of quantum defects such as nitrogen-vacancy (NV) centers allows detection of crystal damage via the strain induced in the crystal lattice, while methods such as x-ray diffraction microscopy allow nanoscale mapping of crystal structure. An alternative method would be to detect the NV centers induced by the WIMP impact in a low-NV-density sample. We present the proposed directional detection principle as well as an overview of recent experimental results. |
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F01.00008: Towards tests of King's Linearity in Ca+ Timothy Chang, S. Charles C Doret We report progress towards a test of King's Linearity in the calcium system via precise measurement of isotope shifts in the 42S1/2→ 32D3/2 (732 nm) and 42S1/2→ 32D5/2 (729 nm) electric quadrupole transitions in Ca+. We co-trap two isotopes and simultaneously excite both ions using frequency sidebands on a single laser, dramatically reducing systematic uncertainties from many sources such as laser frequency drift and magnetic field instabilities. Such measurements have the potential to reach Hz-level precision (part-per-billion) or better. A King Plot made at this level of precision could offer unprecedented sensitivity to probe for the existence of light bosonic Dark Matter and other new physics beyond the Standard Model while also providing benchmarks for ever-improving theory of atomic and nuclear structure. |
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F01.00009: Ultrasensitive Force Sensing with Optically Levitating Nanoparticles Nia Burrell, Chethn Galla, Andrew Laeuger, Evan Weisman, Andrew A Geraci Measuring short-range forces such as deviations to Newtonian gravity or Casimir forces requires precision sensitivity. Optically-levitating nanospheres in vacuum have experimentally been shown to present excellent sensitivity at the zeptonewton scale. Our experiment makes use of precise position control of an optically levitating 300 nm silica sphere in vacuum. We plan to use this system to search for a Yukawa-type correction to Newtonian gravity. Furthermore, successful execution of our experiment can allow us to investigate other short-range surface-force phenomena as well. |
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F01.00010: Optical frequency comb for cryogenic interferometer lock acquisition and calibration Anchal Gupta, Francisco Salces-Carcoba, Yehonathan Drori, rana X adhikari Advanced LIGO uses multi-color cavity metrology to bring several cross-coupled cavities into resonance quickly and robustly. This scheme, known as arm length stabilization (ALS), uses the beatnote between a frequency-doubled auxiliary field and the main laser to stabilize the 4-km arm interferometer into its operating point. Third-generation cryogenic gravitational-wave (GW) detectors such as Voyager will operate well beyond the Si absorption band, i.e. ≥ 1.3 μm, rendering the second harmonic ALS scheme impractical for wavelengths ∽ 2 μm. The auxiliary wavelength is instead chosen to be near 1.5 μm which has no simple relation to the main laser that can be bridged over with a single non-linear interaction. Here, we propose using an optical frequency comb as a beatnote measurement tool between the two wavelengths. We consider a feedforward technique to suppress most of the frequency comb intrinsic noise in the beatnote fluctuations detection and derive the stability requirements based on lock acquisition, and for doing differential strain calibration in future cryogenic gravitational-wave detectors. |
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F01.00011: Nuclear-spin-dependent parity-violating anapole moment in diatomic molecules Yuly A Chamorro Mena, Anastasia Borschevsky, Victor V Flambaum Precision experiments to measure the nuclear--spin-dependent parity violation (NSD-PV) using molecules are promising. The use of molecules gives the possibility to amplify the observable signals using close-lying opposite parity eigenstates. Specifically, in systems containing heavy nuclei, the NSD-PV effects are dominated by the P-odd anapole moment contribution. The measurement of the anapole moment has a relevant impact on nuclear physics as its value is related to a set of parameters describing low-energy hadronic PV interactions. In this work, we study diatomic molecules containing lanthanum and lutetium heavy atoms, as promising candidates for measuring the anapole moment. We use high--accurate electronic structure methods to calculate the enhancement parameter Wa, which describes the sensitivity of this molecule to the anapole moment, and we estimate the uncertainty in our predictions. |
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F01.00012: ATOMIC, MOLECULAR, AND CHARGED PARTICLE COLLISIONS
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F01.00013: Measurement of Photophoretic Forces based on Levitating Particles in a Thermophoretic Trap Huiting Liu, Kelsey Gilchrist, Michelle Chong, Cheng Chin We present an experimental platform to study photophoresis based on levitating particles under the illumination of external radiation. The particles are levitated and trapped in a thermophoretic force field in a vacuum cell. Two orthogonal cameras track the three-dimensional motion of the particles. Microspheres, ranging from 5 to 25 μm in radius, are levitated, and they exhibit different motion under illumination: movement in the direction of laser propagation (positive photophoretic force) and opposite the direction of laser propagation (negative photophoretic force). In an effort to understand our observation vis-à-vis existing models of photophoresis, we simulate the radiation field and temperature distribution of levitated spheres and the thermal cell to extract the photophoretic force from the measurement. Our platform allows for long observation time, repeated experiments on the same particle and has the sensitivity reaching 1 pN. This study of illumination-induced dynamics is an essential step towards use of the laser for optical control of mesoscopic particles, which will widen the possibilities of our levitation scheme as a platform for studying force fields in a microgravity environment. |
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F01.00014: Quantitative comparisons of various approximations within multichannel quantum defect theory (MQDT) for ultracold alkali collisions Nirav P Mehta, Alyson Laskowski We have performed a suite of calculations describing homonuclear two-body ultracold collisions of alkali atoms. Within the framework of MQDT, we identify three distinct approximations. These approximations are primarily characterized by the way in which the short-ranged K-matrix is calculated: (1) The energy-independent frame transformation, (2) The energy-dependent frame transformation, and (3) a rigorous multichannel boundary condition. We compare these three approximations to fully converged coupled channels calculations for collisions of Li-6, Li-7, Na-23, K-39, K-40, Rb-85, Rb-87 and Cs-132, identifying and comparing the positions and widths of s-wave magnetic Feshbach resonances up to 1200G. Frame transformation methods provide a profound computational advantage because they completely avoid numerical solutions to the coupled channels equations, even at short range. By performing a systematic study of homonuclear collisions in the aforementioned species, we are able to identify the conditions under which the frame transformation methods begin to fail, and a rigorous short-range multichannel boundary condition becomes necessary. |
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F01.00015: Modeling C60 Charge Exchange and Fragmentation Jonathan C Smucker Charge exchange in atom-ion systems have been studied for decades due to its relevance to various branches of physics. Recently, there has been more attention drawn to charge exchange collisions with complex targets involving a very large number of degrees of freedom such as large molecules, nano-size clusters, condense matter materials and others. We present a theoretical analysis of C60 charge-transfer processes in slow collisions with various atomic cations. We use a simplified Jellium model to describe C60 electronic sub-system and to reduce the complexity of multi-channel elastic and inelastic processes observed in these collisions. Realistic potentials have been constructed to describe these scattering processes. Combining results of scattering calculations performed with these potentials and Landau-Zener charge transfer theory, we calculated the cross sections from C60 + X+ (X represents Oxygen, Nitrogen or Neon) collisions that agree well with existing experimental data. |
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F01.00016: A rigorous probe of the electronic structure of the Bk and Cf actinide atoms through Regge pole-calculated electron elastic cross sections Alfred Z Msezane, Zineb Felfli A recent experiment [1] identified a weak spin-orbit-coupling in Bk while a j-j coupling scheme described Cf. It concluded that these observations strengthen Cf as a transitional element in the actinide series. Regge pole-calculated low-energy electron elastic total cross sections (TCSs) for Bk and Cf atoms are characterized generally by ground, metastable and excited states negative-ion formation, shape resonances (SRs) and Ramsauer-Townsend (R-T) minima [2]. Additionally, a polarization-induced metastable TCS with a deep R-T minimum near threshold is observed in the Bk TCSs, which flips over to a SR appearing very close to threshold in the Cf TCSs [3]. This behavior manifests the size effect and orbital collapse as well as demonstrates the sensitivity of the R-T minima and SRs to the electronic structure of these atoms, thereby permitting their use as novel validation of the experimental observation.
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F01.00017: The effect of collisions on the rotational angular momentum of diatomic molecules studied using polarized light Ergin H Ahmed, Phillip T Arndt, John P Huennekens, Charles Packard, Vy Tran, Joshua Carey, Rebecca Livingston, Victoria M Marcune, Brendan A Rowe, James Ng, Jianbing Qi, A M Lyyra We report results of an experimental study of the changes in the alignment of the rotational angular momentum of diatomic molecules during elastic collisions. The experiment involved collisions of diatomic lithium molecules in the A1Σu+ excited electronic state with noble gas atoms (helium and argon) in a thermal gas phase sample. Polarized light for excitation was combined with detection of polarization-specific fluorescence in order to achieve magnetitic sublevel state selectivity. Our experimental results show that elastic M changing collisions are allowed, and we measure the collisional rate for such process in J = 1 rotational level. Furthermore, we show that the elastic M-changing collision rate is more than a factor of four times smaller than the inelastic, ΔJ = +2, J-changing collision rate for collisions of Li2 A1Σu+(v = 5, J = 1) molecules with either argon or helium atoms. In other words, it is significantly more difficult for a collision with a noble gas atom to change the orientation of the molecular rotation vector than to change the magnitude of the rotation vector. |
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F01.00018: Electron Ionization of the Ta Atom Stuart Loch, Michael S Pindzola Electron-impact ionization cross sections are calculated for the |
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F01.00019: A Compact 0.7 T Electron Beam Ion Trap using Radial NdFeB Magnets David La Mantia, Aung S Naing, Joseph Tan The study of multiply-ionized atoms has been greatly facilitated by the invention of the electron beam ion trap (EBIT)1, a device developed in the late 1980s for the effective production and trapping of highly-charged ions (HCIs). The original EBIT used superconducting magnets to intensify the electron beam, a costly setup to build and operate. In recent years, rare-earth permanent magnets have facilitated compact, room-temperature EBITs that are better suited for atomic clock research and other applications requiring ions with low ionization thresholds. Based on early efforts2 at NIST, a prototype miniaturized EBIT3 employed a pair of axially-magnetized NdFeB rings yoked by soft-iron drift tubes to produce a peak field of 290 mT at the trap center, demonstrating production of various highly-charged ions such as Ne8+, Ar9+, Ar13+, Kr17+ and other species of HCIs with ionization potential up to 900 eV. In this work, the architecture is redesigned along the lines of a similar compact Penning trap4 which embeds three pairs of radially magnetized rings within yoking electrode structures to yield a higher axial field approaching about 700 mT at the trap center. We report on the progress in building this device, which can operate at electron beam energies up to 5 kV. Possible applications include the calibration of advanced quantum sensors, and the extraction/isolation of mid-Z, mid-q ions for spectroscopy of long-lived states. |
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F01.00020: Electron-impact excitation of Sc II Swaraj S Tayal, Oleg Zatsarinny New large-scale calculations for electron impact excitation collision strengths and radiative parameters for Sc II spectral lines between the 145 fine-structure levels belonging to the 3p63d2, 3p63d4l (l=0-3), 3p63d5l (l=0-3), 3p63d6s, 3p64s2, 3p64s4l (l=0-3), 3p64s5l (l=0-1), and 3p64p2 configurations have been performed. Accurate description of the target wave functions and adequate account of the various interactions between target levels have been determined by a combination of the multiconfiguration Hartree-Fock (MCHF) and the B-spline box-based close-coupling methods together with the nonorthogonal orbitals technique. The valence electron wave functions are described by multichannel expansions in a B-spline basis and are subjected to a boundary condition to become negligible at the boundary. The calculations of collision strengths have been performed using the close-coupling approximation based on the B-spline Breit-Pauli R-matrix method [1]. The relativistic effects in the scattering calculations have been incorporated in the Breit-Pauli Hamiltonian using the one-body Darwin, mass correction, and spin-orbit operators. The likely uncertainties in our results have been estimated by means of comparison with other calculations and experimental radiative parameters. [1] O. Zatsarinny 2006 Comp. Phys. Commun. 174 273. |
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F01.00021: 1,3S and 1,3P electron-positronium scattering Sandra J Ward Quintanilla, William J Mitchell 1,3S and 1,3P electron-positronium scattering |
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F01.00022: Rovibrational transitions in HCl due to collisions with H2 Teri Price, Daniel Hoffman, Josiah Taylor, Benhui Yang, N. Balakrishnan, Phillip C Stancil, Robert C Forrey In this work, we present scattering calculations of HCl with H$_2$ using a new full-dimensional potential energy surface. State-to-state rate coefficients for rovibrational transitions were calculated using a quantum close-coupling method for vibrational quenching in HCl(v1=1, j1)+H2(v2=0, j2) → HCl(v1'=0, j1')+H2(v2'=0, j2' ) collisions, with j1=0-5. Rate coefficients ranging from 5 to 1000 K are presented for both para-H2 (j2=0) and ortho-H2 (j2=1) collision partners. A 5D coupled-states (5D-CS) approximation was used to determine rate coefficients, which were benchmarked against the close-coupling results. Since the 5D-CS approximation reduces the computational time, it was used to extend the database of transitions to include HCl states with v1 = 0 - 2 with j1 up to 30 for temperatures between 10 K and 3000 K.Hyperfine-resolved rate coefficients for rovibrational transitions of HCl were determined by using a recoupling approach and the 5D-CS T-matrices. HCl has been detected in the atmospheres of some planets, as well as in interstellar clouds. It is an important tracer of chlorine, and the rates presented here will allow a better determination of the HCl abundance in the interstellar medium and an improved understanding of interstellar chlorine chemistry. |
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F01.00023: New resonant features observed in the positron annihilation spectrum of aromatic molecules. Soumen Ghosh, James R Danielson, Clifford M Surko Energy resolved positron annihilation spectra for molecules are typically dominated by relatively sharp features that have been identified as vibrational Feshbach resonances (VFR) involving fundamental modes. Recently, new resonances beyond the fundamental modes has been observed in some ring and chain hydrocarbons [1]. Here, we present the annihilation spectrum for benzene (C6H6), fully deuterated benzene (C6D6), and three partially deuterated benzenes (C6H5D, C6H3D3, C6HD5) using a cryogenic positron beam (FWHM ~ 22 meV) [2]. The narrow-energy beam allows for the resolution of new features in the spectra. Several resonances beyond the fundamental modes are observed, and their identification is confirmed by measuring the shifts in these resonances in the partially deuterated molecules. The existence of these resonances confirms that the physics of VFR is not limited only to coupling to fundamental modes. Possible physical interpretations of these resonant features and open questions related to their energies and magnitudes will be discussed. |
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F01.00024: COLD ATOMS, IONS, MOLECULES, AND PLASMAS
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F01.00025: Design of a Meter-Scale Storage Ring for Neutral Atoms William Debenham, Daniel J Heinzen We report on the design of a meter-scale storage ring for neutral lithium atoms. Atoms are to be guided primarily by hexapole magnetic fields produced with permanent magnets. Atoms from an existing intense atomic beam source would be loaded into the ring by optically pumping them from an unguided to a guided state. Stability requirements, similar to those encountered in high-energy particle storage rings, play a crucial role in the design. We calculate the motion of atoms in the ring taking full account of the detailed size, shape, and strength of the individual magnets. We have identified a design that is approximately mode-matched to our existing beam source, and provides stable confinement for hundreds of orbits. The primary motivation for this work is to store exceptionally large numbers of circulating atoms, which could then find application to precision measurement experiments and atom optics, and possibly to coherent matter wave physics. |
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F01.00026: Modelling of a Seeded Supersonic Jet Cold Atom Source Jeremy Glick, William Debenham, Daniel J Heinzen, Jacek Klos, Eite Tiesinga We present a Monte-Carlo simulation of the capture of lithium atoms by a supersonic helium jet. We have calculated fully quantum, differential, lithium-helium scattering cross-sections for use in this simulation. The seeding conditions are similar to those of a new cold atom source we are developing. This source contains a thermal atomic lithium beam directed into the helium jet at a distance of about 1 cm from the nozzle. The nozzle is cryogenically cooled to approximately 5 K to reduce the forward jet velocity. Lithium atoms thermalize with the helium jet, and are then extracted from the jet with a magnetic lens. This experimental approach allows us to reach milliKelvin temperatures in the moving frame, which would not be possible with a pure lithium expansion. A further simulation is then carried out, tracing the atoms through the focusing magnet. Simulation results show reasonable agreement with the experimentally observed focused lithium flux of up to 2 × 1012 s-1 and spot size of 3 to 5 mm. We will also discuss the use of these simulations for further optimization of our cold atom source. |
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F01.00027: Four–body systems near the p–wave unitary regime Michael D Higgins, Chris H Greene N–body interacting bosons and fermions with s–wave interactions at the unitary regime have been extensively studied for many years. Two main classes of systems near the s–wave unitary regime are the BEC-BCS crossover problem, and the three–body Efimov effect and how this effect presents universal behavior in N–boson systems. In this work, four fermion systems with p–wave interactions tuned to different scattering volumes (Vp) are studied using the adiabatic hyperspherical framework with an explicitly correlated Gaussian basis to represent natural and unnatural parity states. Two–body interactions are treated, specifically Gaussian–type interactions as well as soft–core Van der Waals interactions to provide insights for realistic systems relevant to experiment. When the interactions are tuned to the p–wave unitary regime (Vp → ∞), there exists a universal trimer for the Lπ = 1- and 1+ symmetries, where the 1+ trimer is more deeply bound. Attached to these trimer states, exist tetramer states whose potential universal character is under investigation. Four body reaction rates are also computed in this regime for various symmetries that support two–body fragmentation channels in addition to the continuum. |
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F01.00028: Extending the Range of AC Conductivity Measurements in Magnetized Ultracold Neutral Plasmas Jacob L Roberts, Puchang Jiang, John Guthrie, Bridget O'Mara Ultracold neutral plasmas can be used to study basic plasma processes such as electron-ion collisions and AC conductivity under extreme conditions. We have extended our measurement of the influence of magnetization on electron-ion collisions to magnetic fields where the electron Larmor radius is the smallest length scale in the plasma and electron-electron thermalization times are limiting our ability to explore higher magnetic fields with our current technique. Our measurements are compared with theoretical predictions. |
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F01.00029: Migrating an Ion Trap Experiment to ARTIQ: Pitfalls and Community Contributions Ryan A McGill, Kenton R Brown, Craig R Clark, Brian J McMahon ARTIQ offers a modernized solution to hardware and software control over ion trapping experiments [1]. Prior to ARTIQ, many ion trapping setups, including those at GTRI, have successfully employed in-house-developed experiment controllers that require customized programming suites for operation. However, as ion-trap experiments grow more complex, it will be advantageous to employ a more standard solution. Some of the disadvantages to our current experiment control setup include the time and cost of building custom hardware, the limited number of personnel available to uncover and fix bugs, and the use of an obscure scripting language which makes leveraging open-source libraries for hardware control and data analysis challenging. Here we discuss our work to migrate a fully working ion trap from existing equipment to an ARTIQ build. ARTIQ is still in active development, and while there is good documentation online, there is a lack of complete tutorials and examples. This means that mistakes are likely when developing an experimental framework, and we address the pitfalls we have encountered. We also discuss our development of drivers for external devices not currently found within the ARTIQ community, such as for the National Instruments PXIe-5413 DAC, a COTS device which has enabled DC electrode control at clock speeds of 20 MHz in our experiments. |
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F01.00030: Progress Towards a Spin-Specific Microwave Atom Chip Trap William Miyahira, Morgan E Logsdon, Cate Sturner, Sindu Shanmugadas, Jordan Shields, Stephen Rosene, Kerry Wang, Seth Aubin We report on progress in the development of a spin-specific microwave atom chip trap based on the AC Zeeman (ACZ) effect. In this scheme, atoms are trapped in the minima of circularly polarized magnetic near-fields generated by AC currents in atom chip traces. ACZ potentials have applications in atom interferometry, quantum gates, and 1D many-body physics. Our proposed design utilizes multiple microstrip transmission lines to produce traps by overlapping the near-fields of neighboring microstrips. Axial confinement can be provided using a microwave lattice based on the ACZ or AC Stark effect. Ultimately, for an atom interferometer, precisely phase-controlled microwaves can control the axial position of the atoms in the lattice to increase interferometer arm separation or enclose an area. ACZ potentials are inherently spin-specific, able to trap any hyperfine magnetic state, and offer phase and detuning as parameters to control trap features. Additionally, potential roughness from chip wire defects is predicted to be suppressed compared to DC micro-magnetic chip traps. We investigate this in a two-wire configuration. To efficiently couple broadband microwaves onto the microstrip traces, we are developing an interface based on tapered coplanar waveguides. We present electromagnetic simulations of the microwave atom chip and interface designs. |
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F01.00031: Collective chemical reactions and domain wall dynamics in an atomic Bose-Einstein condensate Shu Nagata, Zhendong Zhang, Kai-Xuan Yao, Cheng Chin Chemical reactions in the quantum degenerate regime proceed in a different manner than those of a thermal gas. At ultralow temperatures, quantum statistics can determine the chemical kinetics. We report on the formation of molecules from an atomic Bose-Einstein condensate (BEC) near a g-wave Feshbach resonance. The molecular formation rate below critical temperature greatly differs compared to the thermal regime where the chemical kinetics are affected by atom collisions. When we induce a transition from atoms to molecules in the quantum degenerate regime, the molecular population oscillates at the frequency determined by the molecular binding energy. Our work demonstrates the quantum coherence of collective chemical reactions in a strongly interacting Bose gas. |
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F01.00032: Mesoscopic Magnetic Chip Traps for NASA's Cold Atom Laboratory Leah Phillips, Jason R Williams, David C Aveline, Robert J Thompson NASA’s Cold Atom Lab facility (CAL) provides a unique microgravity environment ideal for ultracold atom experiments investigating fundamental physics, new technologies, and quantum matter [1]. To take advantage of the ISS environment for atom interrogation and precision measurements, atoms must be brought to near rest without strong, confining magnetic fields [2]. Currently CAL’s tight atom chip trap is loaded directly from a quadrupole trap; this is a low efficiency transfer that significantly limits the final total atom number. Due to the atom chip’s current design, the final magnetic trap is also limited in trap frequencies and range of physical translation. As part of a near-term upgrade to CAL, we are investigating an auxiliary mesoscopic magnetic trap design to enable an intermediary stage of the atom loading process for higher transfer efficiency and also provide additional flexibility to generate very low frequency traps and an improved range of aspect ratios. This poster discusses the progress made toward upgrading CAL’s magnetic trap capabilities for reaching higher numbers of ultracold rubidium atoms and potentially colder samples in microgravity. |
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F01.00033: Towards Quantum Simulation of Light-Matter Interfaces with Strontium Atoms in Optical Lattices Jan Trautmann, Annie Jihyun Park, Valentin Kluesener, Dimitry Yankelev, Immanuel Bloch, Sebastian Blatt In the last two decades, quantum simulators based on ultracold atoms in optical lattices have successfully emulated strongly correlated condensed matter systems. With the recent development of quantum gas microscopes, these quantum simulators can now control such systems with single-site resolution. Within the same time period, atomic clocks have also started to take advantage of optical lattices by trapping alkaline-earth-metal atoms such as Sr, and interrogating them with unprecedented precision and accuracy. |
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F01.00034: Lasers for cooling and spectroscopy of 9Be+ and improved UV doubling cavity designs David Fairbank, Alessandro L Banducci, Aron Guerrero, Robert Gunkelman, Connor Taylor, Megan Vildibill, Jacob VanArsdale, Samuel M Brewer Laser cooling of Be+ ions requires a laser system with a wavelength of 313nm. Several schemes for generating mW levels of 313nm laser light have previously been developed, including second harmonic generation of a dye laser operating at 626nm, sum frequency generation based on a pair of fiber lasers, and frequency tripling of an ECDL. Here, we compare the performance of an ECDL-based laser system to a VECSEL-based laser system for use in a frequency quadrupling approach. In both systems, the initial frequency doubling from 1252nm to 626nm is done using a single pass PPLN waveguide doubler. For the final UV doubling stage from 626 nm to 313nm, we have characterized two resonant UV doubling cavities. One cavity design uses a Brewster cut BBO crystal and another is optimized for an AR-coated, flat facet BBO crystal. We present a comparison of the two 313nm laser systems. |
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F01.00035: Robust optical engineering and atomic source development for a Barium ion-based quantum simulator. Noah Greenberg, Ali Binai-Motlagh, Crystal Senko, Kazi Islam, Mahmood Sabooni, Xinghe Tan Interest in trapped-ion physics has grown significantly over the last two decades due to exceptional experimental success, proving it to be one of the leading hardware candidates for quantum information processing and simulation. Harnessing the full potential of this platform requires building increasingly complex machines capable of driving many different atomic transitions and addressing long chains of ions. With this increase in optical complexity, comes an increase in potential points of failure throughout the necessary optical systems required to drive these transitions. To this end, we have designed and built optical systems for fiber coupling, monitoring, and focusing light at the ions that are robust against drifts due to thermal fluctuations and optomechanical failure. The optical components in these systems are mounted directly on thick, custom machined aluminum plates and include dowel pins for precision alignment. We have designed a rack-mountable laser pegboard system with vertically mounted components to reduce footprint, which serves to drive four crucial transitions in our ion trapping experiment. Light captured in our rack system is sent through fiber to our optical table, where we have engineered optics for addressing our ions, capturing fluorescence, and monitoring the optical health of the experiment remotely. Throughout these beam paths, there are many cameras, photodiodes, and motorized optomechanical devices, which aid in pinpointing points of failure in this complex system. In addition to optical work, we touch on the atomic source development of our qubit of choice, Barium-133. This isotope is radioactive and can only be used in microgram quantities. We test different heat treating methods and laser ablation parameters in order to maximize the amount of Barium-133 we will eventually trap from our sample. |
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F01.00036: Towards 780 nm Ion-Photon entanglement John M Hannegan, James Siverns, Qudsia Quraishi Trapped ions excel as networking nodes due to long-lived internal states for local processing and readily accessible ion-photon entanglement. Practical implementation of multi-node quantum networks will likely include different types of quantum technologies with links enabled by quantum frequency conversion. Previously, we demonstrated ion/neutral atom-based hybrid platforms in the form of slow light [1] and two-photon interference between these two different node-types over a 150 m fiber network [2]. These experiments, however, used photons originating from a 138Ba+ trapped ion without measurement of the ion-photon entanglement required in quantum networking protocols [3]. Here, we present our progress on measuring the entanglement between an ion and frequency converted photons at 780 nm. We demonstrate control and detection of ground state and optical qubits and use this as part of a protocol to measure ion-photon entanglement fidelity at both the native ion emission wavelength of 493 nm and the frequency converted wavelength at 780 nm. |
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F01.00037: Towards Cavity-Assisted Doppler Cooling of Ca+ in a Compact Penning Trap Jonathan R Jeffrey, Brian J McMahon, Brian C Sawyer Previous work with 40Ca+ in radiofrequency Paul traps has demonstrated the viability of free-space Doppler laser cooling using electric-dipole-forbidden (e.g. S → D) optical transitions and high-intensity 729 nm laser beams. Some advantages of this “all-infrared” cooling and detection scheme include background-free ultraviolet fluorescence detection and narrow-linewidth Doppler and sub-Doppler ion cooling. We recently developed a compact Penning ion trap based on thermally-stable SmCo permanent magnets and a printed-circuit-board electrode topology. This compact trap is compatible with an in-vacuum Fabry-Perot optical cavity with high finesse at 729 nm. Here we present numerical simulations and experimental progress towards cavity-enhanced, all-infrared Doppler laser cooling in this novel compact Penning trap apparatus. |
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F01.00038: A modular trapped ion node for long distance quantum networking Michael Kwan, James Siverns, Edo Waks
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F01.00039: Quantum sensing and simulations in a Penning ion trap Jennifer F Lilieholm, Matthew J Affolter, Bryce Bullock, Allison L Carter, Elena Jordan, John J Bollinger, Kevin Gilmore, Anthony M Polloreno, Diego E Barberena, Ana Maria Rey, Robert J Lewis-Swan We summarize recent experimental work towards improved quantum sensing and simulations on 2D crystals of over a hundred ions stored in a Penning trap. Our most recent quantum sensing experiments demonstrated a displacement sensitivity of nearly 9dB below the standard quantum limit, which enabled an electric field sensitivity of 240 nV/m/Hz. Over the past year, we have been exploring different paths towards improved quantum sensing and simulations. Through parametric amplification of the axially center-of-mass mode, we should be able to amplify our sensitivity to small displacements and improve our entanglement generation time and fidelity. In order to explore more complicated quantum simulations, we are investigating a path towards single-site addressing of the ion's spin degree of freedom. To that end, we will show theory and experimental work that uses a deformable mirror to create variable AC Stark shifts to address a subgroup of ions. |
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F01.00040: Improving trapped ion motional coherence for quantum simulations of molecular dynamics Tomas Navickas, Ting Rei Tan, Tim F Wohlers-Reichel, Ryan J MacDonell, Arjun Rao, Cornelius Hempel, Ivan Kassal, Michael Biercuk, Michael Biercuk The analog simulation of a quantum chemical system is challenging using conventional computers, particularly in strong vibronic (vibrational and electronic) coupling regimes when the Born-Oppenheimer approximation breaks down. We show that vibronic coupling Hamiltonians representing ultrafast molecular dynamics can be efficiently simulated on quantum systems with coupled internal states and bosonic modes [1]. Furthermore, this “mixed qudit boson” (MQB) approach can be extended to time-domain measurements used to reproduce molecular absorption spectra. We performed proof-of-principle experiments using a trapped-ion system. Time-domain measurements make our simulator susceptible to various mechanisms of decoherence. This places stringent requirements on the simulation time before the system thermalizes with the environment. We identified the limiting factor of simulation times in our system is the bosonic radial mode’s coherence time associated with technical noises within the radio-frequency trapping field. By implementing amplitude noise filtering and feedback, we improve radial mode coherence times from ~1 ms to more than ~20 ms. This enabled us to compute the 1-dimensional Franck-Condon spectra of an SO2 molecule. |
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F01.00041: Towards laser-free dynamical cooling via exchange with a pre-cooled ion Vikram Sandhu, Holly N Tinkey, Spencer Fallek, Ryan A McGill, Craig R Clark, Kenton R Brown The ability to transport ions within a future quantum information processor is expected to play a key role in enabling small subsets of ions to be addressed without crosstalk. This need for transport may necessitate subsequent recooling, as it can be difficult to transport ions without heating them up to the detriment of subsequent quantum operations. Furthermore, anomalous heating increases ion temperatures both during transports and in stationary potentials. As the number of transport operations increases, current recooling methods impose a bottleneck on the speed of trapped-ion quantum information processors [1]. We are currently working towards the experimental implementation of a novel laser-free dynamical cooling scheme [2]. We plan to merge a hot ion with a precooled coolant ion (drawn from a cold reservoir) into the same harmonic potential. During and after the merge, a controllable energy exchange takes place [3], transferring motional quanta from the hot ion to the coolant. After the exchange, the ions are separated and the coolant ion is returned to the cold reservoir. In this work, we lay out our experimental progress, as well as the challenges ahead. |
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F01.00042: Continuous Variable Quantum Computing with Trapped Ions Jasmine Sinanan-Singh, Gabriel Mintzer, Susanna L Todaro, Kyle DeBry, Felix W Knollmann, Xiaoyang Shi, Colin D Bruzewicz, John Chiaverini, Isaac L Chuang The standard approach to quantum computation uses qubits, which are well-described as a two-level system. An alternative approach is continuous-variable quantum computation (CVQC), which uses observables with a continuum of values such as the position and momentum of a particle. CVQC has been explored in other physical platforms, such as superconducting and photonic systems, but there remain open questions about the feasibility and implementation for trapped-ions. In this work, we use the motional modes of trapped ions as our continuous variable and develop protocols for a hybrid boson-qubit system by coupling the bosonic mode to the ion’s electronic state. We report progress toward implementing CVQC operations with electric fields and bi-chromatic laser pulses. We explore using bi-chromatic sideband laser pulses, which provide a spin-dependent displacement on the motional modes, to store and manipulate information in the ion’s bosonic modes. We present a computational framework for simulating CVQC operations in a realistic trapped-ion system with realistic noise sources and preliminary experimental results implementing these operations on 88Sr+ ions. |
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F01.00043: Progress towards a quantum network of 40Ca+ ions trapped in a fiber-based optical cavity Jules M Stuart, Lindsay Sonderhouse, Kaitlyn David, Andrew C Wilson, Daniel H Slichter, Dietrich Leibfried Quantum computers based on trapped ions offer many advantages for executing quantum algorithms, such as long coherence times, precise qubit control and reconfigurable connectivity. As computations increase in complexity, as well as for applications beyond quantum computing, it will be useful to have a photonic interconnect that can entangle distant ion qubits over geographical distances. A network of entangled qubits may, for example, enable increased measurement sensitivity in sensors or increased security in quantum communication protocols. Here we report on our progress to create high-fidelity and high-rate entanglement between ions and telecom-wavelength photons for long-distance entanglement distribution. In our approach, we plan to use calcium ions trapped in a fiber Fabry-Perot optical cavity that is integrated into a surface-electrode ion trap. |
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F01.00044: Fundamental Limits on Gate-Laser Scattering Errors in Barium-133 Samuel Vizvary, Matthew Boguslawski, Zachary J Wall, Isam D Moore, Eric R Hudson, Wesley C Campbell Barium-133 is a promising trapped-ion qubit for large scale quantum computing with easily accessible laser frequencies, robust state preparation, and high fidelity readout. Past theoretical calculations placed a limit on Ba+ stimulated Raman Gate errors due to off resonant photon scattering from the qubit hyperfine ground state to auxillary electron states that limited two-qubit gate fidelities to around 0.999. However, examining the scattering errors with an expanded model for the Raman gate and scattering processes reveals that the error rates can be orders of magnitude lower at readily available gate laser wavelengths. We present a study of measured scattering errors and relate these errors to the ultimate fidelity limits of laser-driven gates in the 133Ba+ qubit. |
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F01.00045: A segmented-blade ion trap with high optical access for quantum information processing Anthony Vogliano, Sainath Motlakunta, Nikhil Kotibhaskar, Jingwen Zhu, Chung-You Shih, Darian Mclaren, Rajibul Islam, Roland Hablutzel Marrero
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F01.00046: Towards a cryogenic vacuum system for rapid testing of ion traps Chaoshen Zhang, Sean W Buechele, Andrew Jayich We present on progress towards a cryogenic trapped ion system for rapid and iterative trap testing. The low vapor pressures of nearly all substances at cryogenic temperatures (<10 K) allow for low vacuum pressures to be quickly realized. The cryogenic stage to which the ion trap is thermally anchored is designed for convenient trap replacement. The design is partly enabled by the wider range of materials that will not outgas due to cryopumping. We plan to take advantage of other features of the cryogenic environment, such as the use of superconducting rings to reduce magnetic field fluctuations, see X. Wang, et al., PRA 81, 062332 (2010). |
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F01.00047: Delaying tunable single photons from a quantum dot with an atomic ensemble Paul Anderson, Rubayet Al Maruf, Sreesh Venuturumilli, Divya Bharadwaj, Sonell Malik, Jiawei Qiu, Yujia Yuan, Philip Poole, Dan Dalacu, Michael E Reimer, Michal Bajcsy InAsP quantum dots embedded in InP nanowires are manufactured to have an emission around the D1 line of cesium (894 nm) and can serve as a bright source of single photons. To interface these photons with atoms, their wavelength has to be controlled with precision that is usually not considered in experiments involving solid-state emitters. To overcome this, we have recently discovered a method of tuning the photon frequency via gas deposition. To characterize the quality of this tunability, we measure the delay experienced by these photons passing through a vapor cell of cesium atoms. Here, we report theoretical estimates and experimental observations of delay of a broadband (~1 GHz) single photons as they transmit through a cloud of warm cesium vapor. |
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F01.00048: Observation of ultracold neutral plasmas using an ion time-of-flight technique Jakub Bystricky, Duncan A Tate, Yu (Coulson) Zhi We have implemented a new technique for observing the expansion ultracold neutral plasmas (UNPs) by stripping the electrons with a fast rise-time electric field pulse (10 ns rise-time, 20 V/cm amplitude) and projecting the ions towards a micro-channel plate detector (MCP). The resulting ion time-of-flight (TOF) signal can then be used to extract the spatial distribution of the ions. By applying the pulse at varying delay times, t, after the UNP creation, we can observe how the radius of the ion distribution, σ, changes with the plasma evolution time. We will describe our progress towards using this technique to obtain the asymptotic plasma expansion velocity, v0. This quantity is found experimentally using σ2 = σ02 + v02 t2, where σ0 is the initial (t = 0) plasma radius, and is related to the effective initial electron temperature, Te,i, by Te,i = mionv02/kB. Values of Te,i are then compared with Te,0, the electron temperature expected from the excess energy of the photons used to create the UNP. |
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F01.00049: Rydberg EIT frequency modulation spectroscopy in Rb Duncan A Tate, Eli Zibello, Kate Jensen We are investigating excitation of nS1/2 and nDJ Rydberg states in Rb using two home-made external cavity diode lasers (ECDLs). Successful excitation of the Rydberg state is detected using electromagnetically-induced transparency (EIT). The probe laser ECDL excites the 5S1/2 → 5P3/2 transition at 780 nm, and the coupling laser ECDL excites the 5P3/2 → nlJ (where n ≈ 25) transition at 483 nm. The probe laser is locked to the F = 4 → F′ = 5 hyperfine component in 85Rb using a Doppler-free DAVLL scheme. The small change in the probe laser absorption when the coupling laser is resonant with a hyperfine component of the 5P3/2 → nlJ transition is detected using frequency-modulation (FM) spectroscopy at 100 MHz. One novel feature of our experiment is that we use an inexpensive Sharp laser diode (GH04850B2G, 60 mW, $30) that free-runs near 488 nm as the coupling ECDL, rather than an expensive commercial (e.g., Toptica) diode laser system where the 480 nm light is produced by frequency doubling light (using an external resonant cavity) from an amplified 960 nm ECDL. Our coupling laser has an output power of approximately 10 mW, rather than 100 - 200 mW available from a commercial system. This necessitates our second innovation, which is that we directly modulate the injection current of the laser diode in the probe ECDL at 100 MHz to do FM spectroscopy, rather than using an external electro-optic modulator. |
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F01.00050: Towards trapped-ion qudit measurement in 137Ba+ by quadrupole shelving Brendan Bramman, Pei Jiang Low, Yvette de Sereville, Matthew L Day, Crystal Senko We present on initial results of trapped-ion qudit shelving measurements using the quadrupole transition in barium ions. We describe shelving sequences which will allow for optimal measurement of up to 5-level qudits using adiabatic passage, and we estimate this protocol to have a fidelity of over 99% for up to 5-level qudits. This work is a first-step towards fully implementing the qudit framework of quantum-information processing in trapped-ion systems. We also observed useful four-level dynamics which allowed us to coarsely tune the 1 Hz laser to the quadrupole transition before fine-tuning by Rabi oscillations. We present progress on spectroscopy of the quadrupole transition and other experimental steps towards full qudit manipulation. |
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F01.00051: Towards a trapped electron quantum computing platform Madhav Dhital, Qian Yu, Alberto M Alonso, Jackie Caminiti, Kristin M Beck, Robert T Sutherland, Dietrich Leibfried, Kayla J Rodriguez, Hartmut Haeffner, Boerge Hemmerling Trapped electrons are an attractive system for a novel quantum computing platform. Their light mass enables fast interactions and their simple two-level system prevents leakage into unwanted states. Quantum information can be encoded in the electron's spin state, which allows for using well-known microwave technology to read out and manipulate the qubit and at the same time avoids the need for complex laser systems. We plan to explore the possibility of creating a scalable quantum computing platform for electrons by combining the advantages of chip-based and macroscopic Paul traps. Here, we present our progress toward trapping and manipulating electrons in a micro-sized 3D-printed linear Paul trap. |
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F01.00052: A Monolithic Three-Dimensional Linear Ion Trap Henry Luo, Michael Straus, Norbert M Linke Trapped ions are a successful platform for quantum information processing, metrology, and many other applications. Compared to microfabricated surface traps, three-dimensional (3D) blade traps benefit from lower heating rate, deeper and more symmetric trapping potential, higher optical access, and better shielding from stray electric fields. However, they are generally assembled from discrete blades and are susceptible to misalignment, which can lead to excess micromotion as well as an inhomogeneous and non-harmonic trapping potential. We present the design and construction of a monolithic 3D blade trap fabricated from a single piece of fused silica, using photochemical processes developed by our collaborator Translume Inc. We discuss the optimization of the trapping potential for a long ion-chain with even spacing. We also present the design of the ceramic structures for mounting the trap, which allows for easy assembly and efficient heat dissipation, while maintaining high optical access. |
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F01.00053: Towards building and controlling large registers of 133Ba+ trapped-ion qubits Andres Vazquez Brennan, Fabian Pokorny, Ana Sotirova, Jamie Leppard, Chris J Ballance The synthetic 133Ba+ isotope has unique properties useful for trapped-ion quantum information processing. It offers long-lived magnetically-insensitive `clock' qubits in the 6S1/2 and 5D5/2 manifolds that can be manipulated with visible and near-IR light [1]. Thus, advanced qubit control schemes can be realised with high fidelity using off-the-shelf optics. We demonstrate an all-fibre Raman system using low noise lasers at 532nm, standard fibre modulators, and a custom laser-written waveguide beam delivery system. |
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F01.00054: Green's function approach to the Bose-Hubbard model with disorder Renan da Silva Souza, Axel Pelster, Francisco E Alves dos Santos We present our results of studing the three different ground states of |
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F01.00055: Optical clocks based on highly charged ions for improved frequency standards and tests of fundamental physics Alessandro L Banducci, David Fairbank, Aron Guerrero, Robert Gunkelman, Megan Vildibill, Connor Taylor, Jacob VanArsdale, Samuel M Brewer Optical clocks based on highly charged ions (HCIs) offer a number of promising avenues for the study of physics beyond the standard model. Among these are searches for time variation of the fine structure constant, (̇α/α), and tests of quantum electrodynamics (QED). Due to level crossings occurring in high charge states, narrow linewidth, optically accessible transitions with a high sensitivity to ̇α/α are predicted in both Nd10+ and Pr10+. We present the status of an ongoing experimental program to perform high-precision, quantum-enabled laser spectroscopy of transitions in these ions. We plan to first create HCIs in a compact electron beam ion trap (EBIT) and then transfer them to a radiofrequency (rf) Paul trap where quantum-logic spectroscopy (QLS) will be performed. In addition, we present an update on the development of a Ba4+ quantum-logic clock as an improved optical frequency standard and an optical fiber link between CSU and the NIST-WWV clock ensemble located in Fort Collins, CO. |
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F01.00056: Experimental Demonstration of Swift Analytical Universal Control over Nearby Transitions Yue Li, Zhi-Cheng He, Xinxing Yuan, Mengxiang Zhang, Chang Liu, Yi-Xuan Wu, Mingdong Zhu, Xi Qin, Zheng-Yuan Xue, Yiheng Lin, Jiangfeng Du We simultaneously drive two near-by transitions with a trapped 9Be+ ion by a time dependent waveform, demonstrating individual and simultaneous quantum control over the transitions even with the average Rabi rates close to their frequency separation[1]. Our demonstration is extended from recent theoretical proposals to simplify the parametrization of the waveform with analytical methods [2,3]. We achieve operation fidelities ranging from 99.2(3)% to 99.6(3)% with approximately an order of magnitude speed up comparing with weak square pulse, conventionally used to resolve nearby transitions. Our work may be able to extend towards working with complicated spectrum for scaled quantum system and high-spin systems, and may be beneficial to a broad range of systems, such as superconducting qubits, phonons in trapped ions. |
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F01.00057: Observation of spin-tensor induced topological phase transitions of triplet degenerate points with a trapped ion Mengxiang Zhang, Xinxing Yuan, Xi-Wang Luo, Chang Liu, Yue Li, Mingdong Zhu, Xi Qin, Yiheng Lin, Jiangfeng Du We work with a three-level system in a trapped $^9\rm{Be}^+$ ion to experimentally simulate a spin-tensor-momentum topological system. We observe different types of triply degenerate points (TDPs) with different topological charge via measuring the Berry flux on a loop around the gap-closing lines, as well as the topological phase transition on the gap-closing point. For measuring the Berry flux, we explore a new method by examining the geometric rotations of both spin vectors and tensors, which differs from spin-1/2 case where Berry flux can be described solely by the rotation of spin vectors. Our work paves the way to explore novel topological phenomena. In addition, the controllable multi-level ion offers an ideal platform to study high-spin topological physics. |
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F01.00058: DEGENERATE GASES AND MANY-BODY PHYSICS
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F01.00059: Potassium condensates in optical tweezers Jeremy Estes, Jared E Pagett, Stephen Yan, Andrew Jayich, David M Weld We present progress on the design and construction of a compact, potassium based neutral cold atom machine which will combine the high precision spatial control of optical tweezers with the creation of degenerate quantum gasses. The machine leverages the small fine and hyperfine structures, and broad Feshbach resonances of potassium, to minimize vector light shifts in tweezers and provide the necessary control over atom-atom interactions for evaporative cooling to quantum degeneracy. With these capabilities we aim to explore fundamental new directions in quantum thermodynamics, simulation of many-body phenomena, and entanglement generation. |
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F01.00060: A new ultracold quantum gas experiment at the University of San Diego Judith Gonzalez Sorribes, Maren E Mossman Ultracold atomic physics experiments provide a flexible platform for studying quantum gas mixtures in a table-top setting. In the Quantum Hydrodynamics Lab at the University of San Diego (a primarily undergraduate institution), we are currently building an apparatus capable of creating and manipulating quantum gas mixtures of rubidium and potassium in 1D and 2D. In this research, we have developed computational models in python to optimize the performance of the apparatus, as well as started to build the physical apparatus. We will discuss the design of the system as well as provide the status of experiments. |
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F01.00061: Progress on studying ultracold atomic bubbles aboard the International Space Station using Science Module 3 of the Cold Atom Laboratory Joseph D Murphree, Nathan Lundblad, David C Aveline, Courtney Lannert, Brendan Rhyno, Smitha Vishveshwara Bose-Einstein condensates (BECs) formed on a thin, hollow shell have a novel topology and are predicted to exhibit interesting collective modes, expansion dynamics, and vortex behavior. Although shell-shaped electromagnetic potentials can be created for dilute atomic clouds by dressing a static magnetic field with radio frequency radiation, the force of gravity in a typical laboratory causes the atoms to pool earthward. NASA's Cold Atom Laboratory (CAL) offers an elegant solution to this problem by allowing ultracold atom experiments to be conducted in the microgravity environment of the International Space Station. We report progress on studying bubbles of ultracold rubidium-87 atoms in rf-dressed potentials using CAL's Science Module 3 (SM3). Bragg spectroscopy is used to explore the momentum properties of the cloud, from which the temperature of the thermal component and presence of the condensed fraction may be determined. We also discuss using CAL's microwave capabilities to create microwave-dressed atomic bubbles. |
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F01.00062: Decoherence and dissociation of 7Li matter-wave breather Sehyun Park, Yi Jin, Ricardo Espinoza, Randy Hulet, Maxim Olshanii Breathers, i.e. higher-order solitons, can be obtained from fundamental solitons by quenching the interaction strength in the nonlinear Schrodinger equation (NLSE). A Bose-Einstein condensate (BEC) confined to a quasi-one dimensional waveguide is a valuable platform to study soliton physics, primarily because of the ability to tune interactions via a Feshbach resonance. In the mean-field (MF) limit, one-dimensional breathers are expected to show a pure periodic oscillation without decay or dissociation due to the integrability of the NLSE. Nevertheless, quantum effects are predicted to cause breathers to undergo a frequency drift of their oscillation [1] and to dissociate into its constituent solitons [2] even at meso- or macroscopic scale. Even in the MF limit, however, systematic effects such as particle loss can produce loss of coherence. In this experiment, matter-wave breathers from a BEC of 7Li are prepared in an optical dipole trap [3]. The axial trap confinement is relaxed sufficiently to prepare the system in the quasi-one dimensional regime. We report the experimental observation of the decoherence and dissociation of breathers at a rate that depends on several parameters, including the number of atoms and the proximity to the collapse threshold. These measurements should help to resolve the role played by quantum effects in our experiment. |
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F01.00063: On-demand generation of dark-bright soliton trains in Bose-Einstein condensates Alejandro Romero Ros, Garyfallia Katsimiga, Panayotis Kevrekidis, Barbara Prinari, Gino Biondini, Peter Schmelcher Dark-bright (DB) solitons are fundamental macroscopic nonlinear excitations that arise in repulsive two-component Bose-Einstein condensates (BECs), whose dynamics and interactions are still an ongoing topic of interest and study. |
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F01.00064: Dynamics of Momentum Bifurcation of Li-6 Molecules in Shaking Optical Lattice Kaiyue Wang, Feng Xiong, Colin V Parker Upon applying a shaking optical lattice to a Bose-Einstein condensate of ultracold Li-6 molecules, we observe deformed bands with two minima resulting from the shaking, as has been previously observed in bosonic species. Time-of-flight measurements show momentum distributions concentrated at the expected quasi-band minima. However, during the evolution from the single minimum to the double minimum, the zone center acquires an inverted dispersion, which resembles the behavior of self-trapped solitons bound by interactions and having negative mass. The atoms remain at this point for a short period, before the momentum distribution acquires a distinct bifurcation into two separated but tight distributions. We here present how we study the process by tuning various variables (shaking time, lattice depth, momentum separation, interactions, etc) and probing techniques. |
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F01.00065: Dynamical excitation processes and correlations of three-body two-dimensional mixtures George Bougas, Simeon Mistakidis, Panos Giannakeas, Peter Schmelcher The quenched dynamics of Bose-Fermi ultracold mixtures in two-dimensional harmonic traps is investigated. For mass-imbalanced three-body systems, we exemplify a selective triggering of the available energy branches by considering different spatial extents of the initial non-interacting state and subsequently switching on the interactions. Our analysis shows that for prequenched non-interacting states with widths smaller than the harmonic oscillator length, trimer and atom-dimer states are predominantly populated, otherwise trap states are substantially contributing in the course of the evolution. The different excitations have a particular imprint in the dynamics of few-body correlations captured by the Tan contacts. The latter provide an independent probe for the dynamical formation of few-body bound states. Overall, the two- and three-body correlations are reduced for increasing width of the initial state. However, in the vicinity of avoided-crossings between trap and atom-dimer states of the post-quenched Hamiltonian the few-body correlations remain sharply enhanced. |
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F01.00066: Progress Towards Realizing One-Dimensional Spin-Orbit-Coupled Bose Gases Shih-Wen Feng, Chuan-Hsun Li, Felicia Martinez, Qi Zhou, Yong P. Chen One-dimensional (1D) quantum systems subject to gauge fields are important platforms to explore novel correlated quantum states yet remain largely unexplored in experiments. Without gauge fields, quantum systems at low energies are generally described by Luttinger liquids whose behavior strongly depends on interparticle interactions. However, spin-orbit coupling (SOC) can notably modify the energy-momentum dispersion, leading to the emergence of unconventional Luttinger liquids whose behavior depends on both SOC and interactions. In experiments, we plan to set up a 2D optical lattice to generate an array of 1D tubes. In addition, 1D SOC along the tube direction is created by a pair of counter-propagating Raman laser beams to atoms. This setup will allow us to explore the equilibrium and excited states of 1D Bose gases subject to SOC at various Raman coupling strengths and interactions. For instance, we can measure atoms' momentum distribution to obtain the single-particle correlation function. Such a correlation is expected to decay exponentially at a critical Raman coupling strength even in the weakly interacting regime, indicating the emergence of non-Luttinger liquids that do not exhibit a quasi-long-range order. |
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F01.00067: Simulating Non-Local Multibody Interactions in a One-Dimensional Ultracold Atomic Gas Philip R Johnson, Nathan L Harshman Local quantum field theories are constructed using delta function interactions, such that elementary point particles only interact when in direct contact. The usual paradigm is that relativity requires local interactions between point particles, and quantum mechanical models involving long-range interaction potentials then arise as effective interactions. Here we explore a class of simple one-dimensional models with non-local, delta function, multibody interactions: a global interaction between two separated particle pairs, that only turns on when the two particles in each pair come in contact. The comparative simplicity of this model allows us to study analytically some fundamental features of non-local interactions without many of the obscuring complications that arise for familiar quantum mechanical long-range potentials. We show how this model can be realized within an ultracold atomic system, making possible the experimental creation of synthetic nonlocal delta function interactions. We further analyze that topologically non-trivial, few body and many-body states occur in the model. |
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F01.00068: Spin-charge separation and pairing in a 1D Fermi gas Aashish Kafle, Ruwan Senaratne, Danyel Cavazos-Cavazos, Sheng Wang, Feng He, Ya-Ting Chang, Han Pu, Xiwen Guan, Randall G Hulet We investigate the behavior of spin-1/2 fermions in one dimension for tunable repulsive and attractive interactions. We confine 6Li atoms to a 2D optical lattice, which forms an array of quasi-one-dimensional waveguides. For repulsive interactions, we realize a Tomonaga-Luttinger liquid (TLL), and observe the low-energy collective excitations and spin-charge separation using Bragg spectroscopy [1]. The velocity of the charge wave increases, while the velocity of the spin wave decreases with increasing interaction strength. The measured Bragg spectra for the two modes compare well with the dynamic structure factors computed using Bethe ansatz and TLL theory [1]. Pairing is expected for attractive interactions. We have observed a pairing gap using RF spectroscopy, showing evidence of molecule formation. The molecular-state binding energy reaches threshold at a zero-crossing of the 3D scattering length on the low-field side of the Feshbach resonance, which exists due to the negative background scattering length of this collision channel. This is the first observation of a so-called confinement induced background dimer, which has no accessible analog in 3D. We map the binding energy as functions of 3D scattering length and confinement strength, and find the molecules to be long lived, perhaps due to their highly-elongated, anisotropic nature. |
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F01.00069: Measuring Rapidities of a Bosonic Dipolar 1D Quantum Gas in Tonks and Super-Tonks Regimes Kangning Yang, Kuan-Yu Li, Kuan-Yu Lin, Benjamin L Lev, Marcos Rigol, Yicheng Zhang, Sarang Gopalakrishnan The distribution of rapidities—quasi-momenta of a one-dimensional (1D) many-body system that depends on the interactions within particles—are of great interest in characterizing many-body states. The bosonic 1D dipolar gas, with its integrability-breaking long-range interactions, is a perfect platform to explore rapidity distributions in a nearly integrable system. We report the measurement of rapidity distributions in a 1D dipolar quantum gas of dysprosium, where we use a Feshbach resonance to tune the short-range interaction strength and a magnetic field angle to tune the long-range dipole-dipole interaction sign and strength. In addition to ground state measurements, we also topologically pump the gas into super-Tonks regime to measure the rapidities of prethermal long-lived excited states (akin to many-body scar states). |
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F01.00070: Realizing a bosonic fractional quantum Hall state with ultracold atoms in an optical lattice Joyce Kwan, Perrin C Segura, Sooshin Kim, Julian Leonard, Markus Greiner
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F01.00071: Chiral Cavity QED in a Synthetic Gauge Field Margaret G Panetta, Clai Owens, Brendan Saxberg, Gabrielle Roberts, Srivatsan Chakram, Ruichao Ma, Andrei Vrajitoarea, Jon Simon, David Schuster We share results from a recent manuscript (arXiv:2109.06033) in which we demonstrate strong coupling between a superconducting transmon qubit and a square lattice of 3D microwave resonators engineered to host a synthetic magnetic field for photons. This quantum nonlinear metamaterial hosts spectrally distinct, topologically protected edge channels and is the first photonic topological lattice platform compatible with strong interactions. We explore cavity quantum electrodynamics in this chiral system: we count and manipulate individual photons in each lattice mode, driving resonant interactions between the nonlinear emitter and individually addressable modes of the topological lattice vacuum, and observe the Lamb shift on the qubit from the synthetic vacuum of the lattice. We share progress towards measurements with multiple nonlinearities coupled to this photonic lattice, enabling communication via the chiral lattice edge channels and opening avenues towards exploring photon-photon interactions and many-body physics in this synthetic quantum material. |
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F01.00072: Exploring parametric resonances in Bose-Einsten condensates with spin-orbit coupling William H Wills, Michael M Forbes Spin-orbit coupling provides a set of useful system parameters to control in cold atom experiments that have applications to spintronics and quantum computation. Here we utilize spin-orbit coupling to probe parametric resonances in computational bosonic superfluids via modulating these parameters in the presence of a potential. |
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F01.00073: Quantum simulating thermalization dynamics of a U(1) lattice gauge theory Guo-Xian Su, Zhaoyu Zhou, Jad C Halimeh, Robert Ott, Hui Sun, Philipp Hauke, Bing Yang, Zhensheng Yuan, Jürgen Berges, Jian-Wei Pan Gauge theories are fundamental to our understanding of modern physics. The highly constrained gauge theory dynamics couples fermionic matter through dynamical gauge fields, which find its applications ranging from early universe cosmology to heavy-ion collisions. However, computing real-time quantum many-body dynamics in these problems is in general beyond the capability of classical computers. Using a 71-site Bose–Hubbard quantum simulator, we study emergent thermal equilibrium in the wake of quenches from out-of-equilibrium initial states and demonstrate the irreversible behavior within unitary dynamics of a U(1) lattice gauge theory. While the unitary quantum evolution admits no loss of information, we find the system relax towards a common steady-state well approximated by a thermal ensemble. Our work paves the way for investigating real-time many-body dynamics of gauge theories, and opens up the possibility of studying more complex generic gauge theories in synthetic quantum matter devices. |
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F01.00074: Rymax-One: Solving Optimization Problems on a Neutral Atom Quantum Computer Niclas Luick Quantum computers are set to advance various domains of science and technology due to their ability to efficiently solve computationally hard problems. Of particular interest are combinatorial optimization problems, whose solutions could provide the basis for optimal supply chains and vehicle routing. However, achieving such a quantum advantage is still prevented by the quality and scale of the available quantum computing hardware. |
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F01.00075: Mapping a Spin Dynamics Resonance Beyond the Single-mode Approximation in a Sodium Spinor Bose-Einstein Shan Zhong, Hio Giap Ooi, Sankalp Prajapati, Jianwen Jie, John E. Moore-Furneaux, Doerte Blume, Arne Schwettmann We present experiments on a resonant coupling between spin and spatial degrees of freedom beyond the single-mode approximation (SMA) during short time non-equilibrium dynamics in a sodium spin-1 Bose-Einstein Condensate. Our quench-induced spin oscillation experiments rely on microwave dressing of the F = 1 hyperfine states where F denotes the total angular momentum of the Na atoms. Our data shows a slow baseline drift of the spin oscillation when the effective quadratic Zeeman shift q is tuned via microwave dressing to certain values. The baseline drift occurring at certain values of q indicates spin dynamics beyond the SMA. Our data agrees well with recent theory, based on a q-dependent, resonant coupling between spin and spatial degrees of freedom. We further explore these effects by scanning q around the point of maximum baseline drift to map out the the width of the complete resonance phenomenon as a function of q. This research has implications for using Bose-Einstein condensates as models for quantum phase transitions and spin squeezing studies as well as for non-linear SU(1,1) interferometers. |
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F01.00076: Study of matter-wave superradiance in a dipolar Erbium BEC Mingchen Huang, Bojeong Seo, Ziting Chen, Mithilesh Parit, Yifei He, Peng Chen, Gyu-Boong Jo Lanthanide atoms such as dysprosium and erbium have attracted significant attention in quantum |
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F01.00077: Dissipation and the Bulk Viscosity in 1D odd-wave Fermi gases Jeff A Maki, Shizhong Zhang One-dimensional Fermi gases at low energy are often described by the Luttinger liquid model. To investigate dissipative effects, it is necessary to include non-linear terms whose form depend on the microscopic details of the system. For example, in the investigation of the bulk viscosity of 1D Fermi gases with even parity interactions, three-body effects are required to generate a finite bulk viscosity. In this talk we address the corresponding question for a non-relativistic spin polarized Fermi gas with odd parity interactions and evaluate the bulk viscosity explicitly. We find results consistent with non-relativistic conformal symmetry, and the bulk viscosity is due to two-body interactions beyond the Luttinger liquid model. |
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F01.00078: Towards the Realization of Tunable Open Quantum System using the Clock Transition Ka Kwan PAK, Zejian Ren, Elnur Hajiyev, Entong ZHAO, Chengdong HE, Gyu-Boong Jo Spin-orbit-coupled (SOC) atoms with tunable dissipation offer a great opportunity to study the non-Hermitian quantum system. In such a system, controlled dissipation is realized by state-selective atom loss which enables the closing of energy gap opened by SOC and allows us to explore chiral behavior of quantum state evolution near the exceptional point (EP). In 173Yb ultracold fermions, for example, a 556 nm transition (1S0 → 3P1) has been used to control the dissipation [1], but there remains a challenge of the study of many-body non-Hermitian physics due to the rapid relaxation of the system. To overcome this, we plan to implement the atom loss using the clock transition 1S0 → 3P0 [2]. We expect the clock transition will prevent atoms from jumping back from excited state to ground state within the experimental time scale, which reduces the undesirable heating and therefore relaxation. |
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F01.00079: LASERS AND QUANTUM OPTICS
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F01.00080: The usefulness of homogeneous coordinates in paraxial optics Theodore A Corcovilos Homogeneous coordinates are a well known tool in the computer graphics community because they allow the expression of rotations, translations, perspective transforms, and affine transformations as linear operators in homogeneous space, but these methods are rarely used in the physics community. Homogeneous coordinates are particularly well suited to paraxial geometric optics because they are the natural setting for projective geometry (specifically oriented projective geometry) which itself underlies optics in the paraxial limit. |
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F01.00081: Exploring the consequences of non-differentiable angular dispersion in optical fields Layton A Hall, Ayman F Abouraddy Diffractive and dispersive devices introduce angular dispersion (AD) into pulsed optical fields. It is commonly assumed that the propagation angle of each wavelength is differentiable with respect to wavelength. However, recently developed space-time (ST) wave packets – propagation-invariant pulsed beams whose spatial and temporal degrees of freedom are intertwined – provide evidence for the existence of ‘non-differentiable’ AD in which the derivative of the propagation angle is not defined at some wavelength. We experimentally explore the unique consequences of introducing non-differentiable AD into a pulsed optical field. Whereas traditional AD ensures luminal group velocities for pulses traveling along the optical axis, we verify that the group velocity of ST wave packets endowed with non-differentiable AD can be tuned arbitrarily. We also confirm that non-differentiable AD enables tuning the group-velocity dispersion in both the normal and anomalous regimes while simultaneously suppressing higher-order dispersion coefficients, or may be used to intentionally suppress or induce there higher-order terms. These characteristics have been realized experimentally using a universal AD synthesizer capable of producing an arbitrary AD spectral profile. These developments may lead to new applications in dispersion compensation and nonlinear optics. |
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F01.00082: Towards narrow-linewidth, superradiant lasing from a hot atomic beam in 40Ca Andrew A Lesak, Sean J Brudney, Aaron X Casserly, Chester J Hamilton Mantel, Jeremy M Metzner, Isam Daniel Moore, Alexander D Quinn, Vikram Sandhu, David J Wineland, David T Allcock Frequency-stabilized lasers serve as the cornerstone of many atomic physics experiments. Stabilization is commonly achieved by electronically locking the laser frequency to a reference cavity. Cavity length fluctuations, resulting from thermal and mechanical noise, limit the laser linewidth, requiring complex cavity-stabilization systems to reach <1 Hz linewidths. Recent proposals have theorized narrow-linewidth lasers operating in the superradiant (‘bad-cavity’) regime based on a simple, thermal atomic beam in which the detrimental effects of cavity length fluctuations are highly suppressed [1]. In this poster, we present the required cooling schemes, atomic beam oven, and cavity needed to achieve narrow-linewidth, superradiant lasing in 40Ca. In addition, we discuss the stability of our in-house laser system that notably features a wavemeter as the main frequency reference and includes the cooling lasers needed to support the superradiant laser and our other, trapped Ca+ ion experiments. |
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F01.00083: Quadrature Shadow Imaging with Thermal Light Ziqi Niu, Savannah Cuozzo, Pratik Barge, Hwang Lee, Lior Cohen, Eugeniy Mikhailov, Irina B Novikova A number of biological objects can only tolerate very low light exposure. This makes imaging them a challenging task since the detection of very low-power optical fields is strongly affected by the dark noise of a camera. |
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F01.00084: Enhancing atomic dark matter and gravitational wave detectors with quantum optimal control Zilin Chen, Timothy Kovachy, Garrett Louie Large-scale atom interferometers using strontium atoms are promising for searching for ultralight dark matter and gravitational waves in a currently unexplored frequency range. In atom interferometry, the atomic superposition states are created and controlled by transferring momentum from laser pulses. The interferometer sensitivity can be enhanced by implementing large momentum transfer (LMT) atomic beam splitters with hundreds or even thousands of pulses which drives atomic transitions between ground and excited states. Deviation from ideal transitions limits the control efficiency and leads to significant atom loss after numerous pulses. During the driving process, deviations can be induced by various factors such as location deviation of atoms in the cloud, non-zero initial velocity spread of atoms respective to the rest-frame, intensity, phase fluctuations and polarization aberration in the laser pulses, and non-zero environmental electromagnetic fields. We manage to drive transitions of the 87Sr atoms in simulation with high fidelity and shorter pulse duration by employing the optimal quantum control techniques which increase the robustness and efficiency of driving pulses against nonideal factors by detuning the amplitude and phase instantaneously and constantly in the pulse duration timescale. |
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F01.00085: Towards trapped atom interferometry for quantum inertial sensing: Creating, shaping and manipulating BECs Alexander Herbst, Knut Stolzenberg, Henning Albers, Sebastian Bode, Dennis Schlippert Position determination for the purpose of navigation plays a crucial role for modern civilization. However, the use of global satellite systems in conjunction with classical inertial sensors has severe limitations due to restricted availability and error accumulation. Trapped atom interferometers are promising candidates for new devices addressing these problems, as they aim to combine the robustness of classical sensors with the precision of light-pulse atom interferometers. |
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F01.00086: Laser system for Stark-shift-compensated dual beam splitters for atom interferometry Minjeong Kim, Joseph Curti, Chris Overstreet, Peter Asenbaum, Remy P Notermans, Mark Kasevich High-power, narrow-linewidth laser systems are important for applications in atom interferometry. The properties of the atom optics lasers that split and recombine the atomic wave packets are often directly related to the performance of an atom interferometer. Here we have developed a laser system that enables Stark-shift-compensated dual beam splitters ideal for low-loss, high-contrast atom interferometry. Up to 40 W of 780 nm beams are generated by frequency-doubling and efficiently overlapping 1560 nm lasers. The optical spectrum spans 370 GHz, centered around the rubidium D2 resonance frequency. We use serrodyne modulation to shift the frequency of each spectral component. Integrating this system into an existing atom interferometer can greatly enhance its sensitivity, making it an excellent probe for studying gravitational interactions in quantum systems. Our recent observation of a gravitational Aharonov-Bohm effect is discussed. Other applications include a more precise test of the equivalence principle, or a measurement of the gravitational constant. Further upgrades such as higher modulation bandwidth are under way. |
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F01.00087: Matter Wave Analog of a Fiber-Optic Gyroscope Katarzyna Krzyzanowska, Saurabh Pandey, Ceren Uzun, Malcolm G Boshier Confining the propagating wavepackets of an atom interferometer inside a waveguide can substantially reduce the size of the device while preserving high sensitivity. We have used the moving guide technique to create the first waveguide Sagnac atom interferometer. An 87Rb BEC is formed near the focus of a waveguide made by a single red-detuned beam. The BEC is split, reflected, and recombined with a series of Bragg pulses while the waveguide moves transversely so that the wavepacket trajectories enclose an area. We demonstrated single and multiple loop architecture. We also showed that the device can operate along both horizontal and vertical axis, which means that the moving guide approach is suitable for measuring rotation in all directions. Moreover, interference fringe was obtained for wavepackets propagating with splitting momenta higher than 2hk, up to 6hk. In this talk/poster, we will describe recent progress on the experiment, including increases in enclosed area and coherence time, and discuss important limitations of this type of atom interferometer. |
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F01.00088: An Atomic Fabry-Perot for the Generation and Measurement of Ultracold Wavepackets Nicholas Mantella, Joseph McGowan IV, Harshil Neeraj, David C Spierings, Aephraim M Steinberg A matter-wave Fabry-Perot (FP) for the generation of ultracold wavepackets could be implemented using an optical double barrier. Observation of the transmission spectrum of a single such FP becomes impractical for wavepacket temperatures above about 100pK. The resonances are washed out due to the velocity width of the incident wavepacket being larger than the width of the resonances. We propose a scheme for using a second atomic FP with a tunable cavity length to characterize the filtering properties of the first. Gross-Pitaevskii (GP) simulations of a 87Rb BEC interacting with double-Gaussian potentials show that evidence of resonant transmission can be observed using this scheme. The GP simulations use experimentally achievable parameters of a 1nK 87Rb BEC of a few thousand atoms, incident on barriers with a 1/e2 radius of 1.3 µm. With these parameters, BECs containing a few hundred atoms could be generated at a temperature less than 50pK. We plan to realize this scheme experimentally using a spatial light modulator to manipulate the optical potential for the tunable cavity length matter-wave FP. |
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F01.00089: The Hannover Very Long Baseline Atom Interferometer Dennis Schlippert, Henning Albers, Vishu Gupta, Ali Lezeik, Christian Meiners, Abhishek Purohit, Christian Schubert, Dorothee Tell, Klaus H Zipfel, Ernst M Rasel Very Long Baseline Atom Interferometry (VLBAI) corresponds to groundbased atomic matter-wave interferometry on large scales in space and time, letting the atomic wave functions interfere after free evolution times of several seconds or wave packet separation at the scale of meters. As inertial sensors, e.g., accelerometers, these devices take advantage of the quadratic scaling of the leading order phase shift with the free evolution time to enhance their sensitivity, giving rise to compelling experiments. With shot noise-limited instabilities better than 10−9 m/s2 at 1 s at the horizon, the Hannover VLBAI facility may compete with state-of-the-art superconducting gravimeters, while providing absolute instead of relative measurements. Operated with rubidium and ytterbium simultaneously, tests of the universality of free fall at a level of parts in 1013 and beyond are in reach. Finally, the large spatial extent of the interferometer allows one to probe the limits of coherence at macroscopic scales as well as the interplay of quantum mechanics and gravity. We report on the status of the VLBAI facility, its key features - the high-flux atomic sources for Rb and Yb, the 10 m magnetic shield, and the low-noise seismic attenuation system - and future prospects in fundamental science. |
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F01.00090: High-fidelity splitting of Bose-Einstein condensates into high-order momentum states Ceren Uzun, Saurabh Pandey, Vashisth Tiwari, Katarzyna Krzyzanowska, Malcolm G Boshier Matter-wave interferometers that are based on Bose-Einstein condensates (BEC) have important precision-measurement applications in both fundamental sciences and in improvement of devices like accelerometers and rotation sensors. A crucial part of realizing a BEC-based interferometer is the matter-wave beam splitter. Optimal splitting of a stationary BEC into a linear superposition of states with high momentum enables the split matter-waves to travel further and thus, increases the sensitivity of matter-wave interferometers. Recent work (Cassidy et al., J. Appl. Phys., 130, 194402 (2021)) has numerically explored different shapes of optical splitting pulses for achieving high-momentum states with robust fidelity. In this work, we experimentally investigate splitting Bose-Einstein condensates into high-order target momentum states using optical standing-wave Bragg pulse sequences of various shapes. We also numerically explore the high-order momentum splitting dynamics with different pulse shapes using one-dimensional Gross-Pitaevskii (GPE) simulations. We will report the comparison between our splitting experiments and the GPE simulations. |
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F01.00091: A Loadlock Chamber for Cavity QED Henry Ando, Chuan Yin, Jonathan Simon By interfacing optical cavities with cold atoms, one can achieve strong light-matter coupling and engineer effective interactions between photons. In our group we are experimenting with many novel cavity designs, so a major technical speed bump we face is opening and baking our UHV system every time a new optical cavity is installed. We present here on a solution which obviates the large majority of the labor involved in the installation of new cavities into the vacuum system: a loadlock with a translator. The vacuum system consists of two separate chambers separated by a gate valve, one for science which never breaks vacuum (the "science" chamber), and one for opening to install new cavities (the "loadlock" chamber). Once a new cavity is installed and baked in the loadlock chamber, it is carried through the gate valve by the translator, all under UHV conditions. This enables new cavities to be installed without disturbing any of the optics for the MOT, imaging, or lattice systems, reducing the installation time by weeks. We present here on the design principles and current status of the apparatus. |
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F01.00092: Angular momentum transfer via virtual atomic excitations Claire Baum, Matthew Jaffe, Lukas Palm, Jonathan Simon The tunability of atomic parameters has made atomic systems an appealing experimental platform. We utilize the tunability of atomic energy levels to transfer angular momentum to photons. By spatiotemporally modulating a cloud of 87Rb at the waist of a twisted cavity with a far-detuned Stark-shifting beam, photons that pass through the cloud are converted to different angular momentum modes of the cavity. We observe this conversion and achieve the maximum theoretical conversion efficiency, demonstrating the coherent modification of photonic degrees of freedom and prospects for engineering couplings between arbitrary modes. |
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F01.00093: Atom-Nanophotonic Quantum Network Node with Direct Telecom Operation Noah Glachman, Shankar G Menon, Yuzhou Chai, Kevin Singh, Alan M Dibos, Johannes Borregaard, Hannes Bernien Practical quantum networks designed for long distance operation require the use of telecom photons to mitigate fiber losses. However, many promising qubit candidates do not have ground state telecom transitions. We propose a scheme that overcomes this limitation by strongly coupling atomic qubits to telecom nanophotonic cavities which both provide the efficient light-matter interface necessary for a quantum network node and circumvent the need for frequency conversion by exploiting excited-excited state transitions. Specifically, our scheme creates robust time-bin entanglement between the atomic hyperfine ground states and telecom photons collected via the cavity mode. We show that high fidelity entanglement can be generated with experimentally realistic parameters including cavity coupling strength, finite atomic temperature, and polarization impurity of the addressing lasers due to the nearby dielectric surface. |
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F01.00094: Two-Qubit Nanophotonic Quantum Network Node Using Strained Silicon-Vacancy Spins in Diamond Yan Qi Huan, Pieter-Jan C Stas, David Levonian, Bartholomeus Machielse, Denis D Sukachev, Aziza Suleymanzade, Erik Knall, Benjamin Pingault, Can M Knaut, Daniel Assumpcao, YAN-CHENG WEI, Mihir K Bhaskar, Hongkun Park, Marko Loncar, Mikhail Lukin Quantum nodes incorporating a long-lifetime quantum memory and a high-fidelity spin-photon interface are a crucial component of long-range quantum networks. Here, we report on the deterministic creation of such nodes based on the 29Si-isotope silicon-vacancy center (SiV) platform in diamond nanophotonic cavities, where the optically-accessible SiV electronic spin is combined with a reproducible nuclear spin memory qubit in an integrated two-qubit register. We demonstrate the necessary operations for a quantum network node, namely: spin-photon gates between the electron spin and a time-bin encoded photon, storage of the electron qubit state in the nuclear memory, and repeated electron initializations while preserving the nuclear memory. We perform these operations on a highly-strained SiV, leading to continued coherent operation even above typical dilution refrigerator temperatures, thus easing the way for a full implementation of the quantum repeater and entanglement distillation protocols between multiple nodes. |
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F01.00095: Ultrafast Local State Detection of Single Atoms and Deterministic Loading of Tweezer Array Using Cavity Readout Yuehui Lu We investigate an atomic array coupled to a high-finesse optical cavity. This system is a versatile platform for exploring open many-body quantum dynamics, implementing quantum error correction, and testing quantum advantage. |
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F01.00096: Integrating Twisted Cavities and Rydberg Atoms for Photonic Quantum Matter Lukas Palm, Matthew Jaffe, Claire Baum, Jon Simon Twisted optical cavities are a powerful tool to shape the photonic energy landscape and create artificial gauge fields for light. We combine these optical tools with ultracold atoms to imbue photons with interactions by turning them into quasiparticles called cavity Rydberg polaritons. Achievable size of many-body states using this hybrid platform is limited by the number of degenerate optical cavity modes as well as atomic density. We describe our recent efforts in designing and building a highly integrated apparatus containing a twisted resonator using intra-cavity lenses, a twisted build-up cavity for Rydberg excitation light, electric field control as well as in-vacuum alignment capabilities. With this system combining quantum optics techniques and Rydberg atoms we want to realize and probe highly correlated quantum phases of matter. |
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F01.00097: Demonstration of atom-light interaction on a nanophotonic microring circuit Xinchao Zhou, HIKARU TAMURA, Tzu-Han Chang, Sambit Banerjee, Chen-Lung Hung Interfacing cold atoms with nanoscale photonic structures promises stronger atom-light interactions and novel quantum functionalities via dispersion engineering, controlled photon propagation, topology, and chiral quantum transport. Our approach is based on high quality silicon nitride microring resonators fabricated on a transparent membrane substrate, which is compatible with laser cooling and trapping of cold atoms. This platform holds great promises as a scalable on-chip atom cavity QED system with strong and cooperative atom-light coupling. In this poster, we demonstrate an efficient optical guiding technique for trapping cold atoms in the near field of a planar nanophotonic circuit, realize atom-photon coupling to a whispering-gallery mode in a microring resonator. From the observation of the atom-induced transparency for light coupled to a microring, we characterize the atom-photon coupling rate, extract guided atom flux, and further explore the possibility of trapping single guided atoms directly on the microring waveguide. Our demonstration paves a way to explore collective quantum optics and many-body physics by forming an organized atom–nanophotonic hybrid lattice and inducing tunable long-range atom-atom interactions with photons on a nanophotonic circuit. |
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F01.00098: Progress towards the Strong Interaction between Thermal Atoms and Microring Resonator with High-Quality Factor Linzhao Zhuo, Bochao Wei, Chao Li, Alexandra P Crawford, Ali E Dorche, Kirsten Masselink, Ali Adibi, Chandra Raman Quantum sensors based on thermal atoms offer simplicity in comparison to laser cooling and may further have lower vacuum requirements. In this work, we investigate single-atom detectability based on strong coupling of thermal atoms to a micro-ring resonator with a high quality (high-Q) factor. In our experimental platform, we fabricate a silicon nitride (SiN) high-Q microring resonator on an integrated photonic chip with bus waveguides to couple light in and out through the edge. The chip is attached to a thermoelectric cooler (TEC) that is capable of tuning and stabilizing the resonance frequency of the resonator to the D2 optical transition of 87Rb at 780 nm. The customized assembly is hosted in a quartz cell under a vacuum level of 10-6 Torr which is much higher than the pressure used in cold atom systems. The laser beam is coupled in and out of the bus waveguide using long working distance microscope objective in a confocal configuration to achieve high coupling efficiency. We then generate the atomic vapor by inductively heating a welded loop of Rb dispensers. This platform enables the study of the interaction between thermal atoms and SiN resonators in order to investigate atom-light interactions at a miniature scale. |
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F01.00099: Towards on-site absolute calibration of single photon detectors with high accuracy Francisco E Becerra, Sujeet Pani, Duncan Earl Single photon detectors are ubiquitous in many protocols for quantum communications and quantum information processing. Many of these applications critically depend on precise knowledge of the detection efficiency of these detectors. Different methods for determining the efficiency of single photon detectors have been pursued including the use of transfer standard detectors and different sources of light. A method based on the use of a source of quantum correlated photon pairs provides means for realizing the absolute calibration of single photon detectors with high accuracy [1]. Given the nature of the generation process in the sources of photon pairs, every time a photon is detected, there is in principle absolute certainty that a second photon exists. This information provides a natural way for measuring the detection efficiency of a single photon detector in absolute terms with high accuracy [2]. We investigate the potential for implementing this calibration method based on a commercial source of quantum correlated photons for on-site calibration of single photon detectors without requiring any standard. We compare this calibration method with the calibration method based on transfer standard detectors using stable laser sources. We observe that while the efficiency of the source of quantum correlated photons directly affects the determination of the detector efficiency, the accurate calibration of the source could provide a path for making this method a viable way for realizing on-site absolute detector calibration. |
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F01.00100: A mathematically derived formula revealing the nature of Doppler effect and Cherenkov radiation Qian Chen Currently, the nature of Doppler effect was not fully clear. For example, all Doppler effect formulas only work for constant velocities. Hence, what is the implication of a time-varying velocity in the Doppler effect? A general formula is mathematically derived purely from the principle of constant light speed, which provides a straightforward mathematical explanation of the fundamental nature of Doppler effect. This single formula covers the classical and transverse Doppler effects and applies to time-varying velocities. It is also supported by existing experiments of Doppler effect and theoretically proved by Maxwell’s wave equations. This formula shows that the Doppler effect is the result of the time scaling factor between the light emission time and the observation time caused by the varying propagation delay due to the relative motion between the light origin and observer. Furthermore, this same formula also provides a straightforward mathematical explanation of Cherenkov radiation and Cosmological red-shift. The fact that all these physical phenomenons can be mathematically explained by the same general formula is interesting. These findings are just part of a new theoretic framework mathematically derived from the principle of constant light speed, named as “Asymmetry Theory”, which is comprehensive, self-consistent, and in harmony with all existing experiments. |
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F01.00101: Kapitza-Dirac Blockade: A Universal Tool for the Deterministic Preparation of Non-Gaussian Oscillator States Herman Batelaan, Wayne Cheng-Wei Huang, Markus Arndt “Harmonic oscillators count among the most fundamental quantum systems with important applications in molecular physics, nanoparticle trapping, and quantum information processing. Their equidistant energy level spacing is often a desired feature, but at the same time a challenge if the goal is to deterministically populate specific eigenstates. Here, we show how interference in the transition amplitudes in a bichromatic laser field can suppress the sequential climbing of harmonic oscillator states (Kapitza-Dirac blockade) and achieve selective excitation of energy eigenstates, cat states, and other non-Gaussian states [1]. This technique can transform the harmonic oscillator into a coherent two-level system or be used to build a large momentum-transfer beam splitter for matter waves. To illustrate the universality of the concept, we discuss feasible experiments that cover many orders of magnitude in mass, from single electrons over large molecules to dielectric nanoparticles.” [1] Wayne Cheng-Wei Huang, Herman Batelaan, and Markus Arndt, Phys. Rev. Lett. 126, 253601 (2021). |
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F01.00102: Robust Atom Optics for Large Momentum Transfer Atom Interferometry with Strontium-88 Garrett Louie, Tejas Deshpande, Zilin Chen, Timothy Kovachy Large momentum transfer (LMT) atom interferometry requires atom optics with near unity population transfer and stable phase control, which are limited by noise factors such as thermal cloud expansion, stray magnetic fields, and laser fluctuations. To allow greater momentum transfer under a broad range of experimental conditions, we use the quantum optimal control Python toolkit developed by Q-CTRL to engineer amplitude and phase-modulated pulses for the 461 nm (multi-photon Bragg) and 689 nm (single-photon) transitions of Sr-88. We have simulated π-pulses maintaining over 99.9% population transfer and phase stability across several static and time-dependent noise channels, which couple as power, frequency, and polarization errors. These are more robust at a given laser power without exceeding the duration of typical Gaussian and composite pulses. We also report on progress towards implementation of the 689 nm pulses for point-source interferometry (PSI) with a hot (~1 mK) cloud [1][2]. The 6W output from a pair of Ti:sapphire lasers is shaped into arbitrary pulses via AOMs driven by a quadrature modulated rf signal. Such pulses could later be used as wavefront diagnostics during operation of colder interferometers such as MAGIS-100 [3]. |
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F01.00103: Realization of a gravity gradiometer with a waveguide atom interferometer Changhyun Ryu, Kevin Henderson Accurate measurement of gravitational force has many important applications, from geophysical exploration to gravitational wave detection. A gravity gradiometer can be used to detect gravitational signatures without vibration noise for these applications. An atom interferometer in free space has been used to develop one of the most sensitive gravity gradiometers. However, the required significant interrogation time results in a considerable free fall distance, making it challenging to create a portable sensor and increase the sensitivity for the most critical applications. Here, we report the realization of a gravity gradiometer with a waveguide atom interferometer with which atoms are guided during the interrogation without free fall. With two separate clouds of Rb atoms on a waveguide, a differential measurement of the acceleration of atoms was made, which can be used to detect gravity gradients along the axial direction of the guide beam. The coherent interrogation time up to 80ms was demonstrated, and a further increase is being investigated by reducing relative phase fluctuations from various sources. The progress of this project will be reported. |
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F01.00104: Fiber-Coupled Twin Beams from Four Wave Mixing in Rubidium Umang Jain, Jae H Choi, Christopher Hull, Alberto M Marino The reduced noise properties of twin beams make it possible to enhance the sensitivity of measurements beyond the classical shot noise limit (SNL). Expanding such capabilities beyond proof-of-principle experiments and into practical applications will require technological advancements, such as the implementation of fiber coupled compact sources. We show that it is possible to generate fiber coupled twin beams with a large degree of quantum correlations. We generate the twin beams with a nonlinear four wave mixing (FWM) process in a double-Λ configuration in rubidium vapor. In this process the absorption of two pump photons leads to the simultaneous generation of probe and conjugate photons, which gives rise to the quantum correlations. In order to generate bright twin beams, we combine the pump beam with a seed probe beam at a slight angle at the center of a hot rubidium vapor cell. The generated bright probe and conjugate beams are then fiber coupled to two separate single mode fibers with ∼90% coupling efficiency. In doing so, special care needs to be taken due to the multi-spatial-mode nature of the twin beams. We optimize the FWM process to maximize the level of squeezing while minimizing the number of spatial modes in the generated probe and conjugate beams. We show that is possible to obtain fiber coupled twin beams with ∼ 4.5 dB of intensity difference squeezing out of an initial level of ∼ 7 dB of squeezing. |
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F01.00105: Scalable Source of Multipartite Entangled States of Light Daida Thomas, Saesun Kim, Alberto M Marino Continuous variable multipartite entanglement (CVME) is a valuable resource for quantum information science and quantum computation, as it can enable a stronger violation of bell-type inequalities. Due to the strong non-locality, it can benefit applications such as quantum teleportation, dense coding, and quantum sensing. It is also a necessary resource for applications such as controlled quantum secure direct communications in which a third party acts as a controller for secure communication between any two parties in a network. Experimental realizations of CVME have already been demonstrated with different configurations, such as cascaded parametric amplifiers, beam splitter networks with input single mode squeezed states of light, and time-bin multiplexing of squeezed light sources in the temporal domain. Here, we present our preliminary experimental results on the implementation of a scheme to generate genuine CVME through the use of spatial modes. The system consists of an SU(1,1) like interferometer with two four wave mixing processes serving as the source and mixing element for the different spatial modes. The setup contains only two active elements and offers the advantage of providing a simpler and scalable technique for the generation and verification of genuine multipartite entanglement in the spatial domain. |
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F01.00106: Atom-atom van der Waals Interactions through a Lens Aníbal L Olivera, Kanupriya Sinha, Pablo Solano We study the fluctuation-mediated interactions between two atoms in the presence of an aplanatic lens, demonstrating an enhancement in the resonant part of their van der Waals interaction. We derive the field propagation of the linear optical system in terms of its electromagnetic Green's tensor. We analyze the collective internal atomic dynamics via a Lindblad master equation, which allows one to characterize the dispersive and dissipative interactions between atoms. Furthermore we describe the quantized center of mass dynamics of the atoms, studying the possibility of creating a novel trapping mechanism. Our work opens new avenues for expanding van der Waals interactions to macroscopic scales and the experimental platforms to study them. |
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F01.00107: Creating knots in spinor Bose-Einstein condensates via a Raman process Zekai Chen, Elisha B Haber, Nicholas P Bigelow The study on three-dimensional topological defects draws a broad interest in condensed matter physics, fluid dynamics, biology, quantum information and cold atom physics. Creating three-dimensional topological defects such as knots in ultracold atomic gases is of interest because it can allow us to study the interaction and evolution of such topological features in a superfluid. In this work, we propose an experimentally feasible protocol to imprint knotted topological excitations onto the wavefunction of a dilute pseudo-spin-1/2 Bose-Einstein condensate (BEC) via a Raman process. Our calculation shows that these topological excitations can be imprinted by engineering the spatial profiles of the Raman laser fields. Additionally, we demonstrate the capability to adjust the size and the aspect ratio of the knotted nodal line by tuning the parameters of the Raman lasers. |
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F01.00108: QUANTUM INFORMATION SCIENCE
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F01.00109: A Landau Theory for Spin Squeezing Maxwell B Block, Bingtian Ye, Sabrina Chern, Emily J Davis, Norman Y Yao Generating spin-squeezed states in quantum simulators with power-law interactions is a key experimental challenge with limited theoretical guidance. While numerical evidence suggests it should be possible to achieve spin squeezing with sufficiently long-range (but still energetically extensive) XXZ Hamiltonians, the precise requirements remain unclear. Here, we conjecture a comprehensive explanation for the "squeezing phase diagram" of long-range XXZ models. While squeezing in such models is dynamically generated by time evolution from simple product states, our explanation is intimately connected to the presence of finite-temperature equilibrium order in the Hamiltonian and thermalization within symmetry sectors of fixed total magnetization. Using a variety of numerical methods, we test our conjecture in one-dimensional models and find necessary and sufficient conditions for spin squeezing. We discuss the implications of these conditions for realizing spin-squeezing in a variety of quantum simulation platforms. |
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F01.00110: Unambiguous state discrimination as a limit of an optimal nonprojective measurement of binary coherent states Spencer D Dimitroff, Elohim Becerra, Matt T DiMario Recent advances in quantum measurement theory have shown that it is possible to realize an optimal inconclusive measurement of binary nonorthogonal coherent states based on linear optics, coherent displacement operations, continuous photon counting, and fast feedback [1]. The optimal inconclusive measurement is a nonprojective quantum measurement that generalizes the minimum error (Helstrom) measurement and the optimal unambiguous measurement of binary states, achieving the minimum error probability for a given probability of an inconclusive result. We study this optimal nonprojective measurement to implement the zero-error optimal unambiguous state discrimination (USD) of binary coherent states. While it is possible to implement optimal USD of binary coherent states with a measurement based on displacement operations to the vacuum state without feedback [2], it is known that such an optimal quantum measurement cannot be implemented in the presence of experimental imperfections due to the impossibility of perfectly realizing this displacement operation. We explore the use of the optimal inconclusive measurement in this zero-error regime, which does not fully rely on displacement operations to the vacuum state, with the aim of demonstrating a USD measurement that is more robust to experimental imperfections. This robust quantum measurement can be critical in realistic implementations of quantum communication protocols based on USD of coherent states. |
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F01.00111: Numerically simulating Doppler effects in coherent spectroscopy of warm Rydberg atoms Paul Kunz, Brielle E Anderson, Donald P Fahey, Kevin C Cox, David H Meyer A relatively new class of warm vapor-based quantum sensor, the Rydberg electric field sensor, is being investigated by a growing number of groups around the world. These sensors rely on coherent spectroscopy of highly excited Rydberg states, and there is a need to identify preferable optical schemes among the numerous possibilities. Choosing a combination of three or more wavelengths opens the possibility for configuring the beams to cancel the total photon momenta, i.e. the optical wavevectors sum to zero. Simulating such experiments can be computationally intensive given the number of atomic levels, electric fields, and motional degrees of freedom involved. We present numerical simulations that well match our experimental data. This both informs optimization of the experiment, and gives insights into mechanisms that are most relevant to the sensor's signal-to-noise ratio. |
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F01.00112: Super-resolution Airy disk microscopy of individual color centers in diamond Aedan Robert H Gardill, Ishita Kemeny, Yanfei Li, Maryam Zahedian, Xiyu Xu, Matthew C Cambria, Jennifer Choy, Ádám Gali, Vincenzo Lordi, Jeronimo R Maze, Shimon Kolkowitz Super-resolution imaging techniques are critical to nanoscale microscopy in fields such as physics, biology, and chemistry. However, many super-resolution techniques require specialized optics components such as the vortex-waveplates used for stimulated emission and depletion (STED) microscopy. We present a novel technique, Super-resolution Airy disk Microscopy (SAM) that can be used in any standard confocal microscope without the need for specialized optics or physical modifications to the microscope. We demonstrate this technique using ground state depletion by imaging nitrogen-vacancy (NV) centers in bulk diamond below the diffraction limit. We achieve a greater than 14x fold improvement in resolution compared to the diffraction limit, corresponding to a measured spatial resolution of 16.6(8) nm. We illustrate the utility of this technique by localizing and performing individual measurements on pairs of NV centers separated by less than the diffraction limit, including two NV centers with the same orientation. Part of this work was performed under the auspices of US DOE by LLNL under Contract DE-AC52-07NA27344. |
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F01.00113: Optical and magnetic properties of Rb-doped Ne solids David M Lancaster, Ugne Dargyte, Jonathan D Weinstein Single-atom quantum sensors require long coherence times and the ability to detect and control the atom's quantum state. We have found that the spin state of Rb atoms trapped in cryogenic neon solids satisfies these requirements, making this system a promising one for magnetometry of materials co-trapped in the matrix and for single-molecule NMR. This poster presents key optical and magnetic properties of Rb atoms in solid Ne, modifications to our apparatus to enable single-atom detection in the matrix, and our current progress towards that goal. |
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F01.00114: Equivalent Circuit Models of the Matter Wave Transistor Oscillator Hannah North, Dana Z Anderson, Seth Caliga A triple-well atomtronic transistor is an atomic potential consisting of source, gate, and drain potential wells defined by a pair of closely-spaced, gaussian optical barriers. When appropriately configured with a finite temperature Bose-Einstein condensate (BEC) in the source well the system will oscillate and emit a coherent matter wave into the drain in much the same way that an electronic transistor oscillator emits a coherent electromagnetic wave when coupled to the vacuum through an antenna. The underlying physics involving many-body interactions is complex (D.Z. Anderson, Phys. Rev A, 104, 033311 (2021). However, system design and understanding is substantially facilitated by an equivalent circuit model. In such an atomtronic circuit, standard circuit principles and heuristics such as Kirchhoff's voltage (potential difference) and current (atom flux) apply. We describe the principles of the atomtronic transistor oscillator through such equivalent circuits using standard electric circuit concepts. We also discuss the properties of the emitted matter waves, which are distinct from the more familiar de Broglie waves. The waves are well suited to matterwave interferometric sensing. |
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F01.00115: Entanglement generation and quantum random walks in strontium atom arrays Nathan A Schine, Aaron W Young, William J Eckner, Adam M Kaufman Tweezer arrays of neutral divalent atoms can simultaneously realize the numerous requirements for explorations of quantum many body physics, quantum information processing, and quantum-enhanced optical clocks, namely low entropy state initialization, high fidelity quantum control and entanglement generation, and long coherence times on optical transitions. In order to scale these capabilities to hundreds of atoms, we utilize hybrid trapping potentials defined by both optical tweezers and a 3d optical lattice. We report on the implementation of atom rearrangement in 2d within the lattice and its impact on investigations of Rydberg-mediated clock-qubit spin squeezing, which produces metrologically relevant entangled states and enables systematic explorations of the transverse-field Ising model. Atom rearrangement will also enable explorations of multi-atom Hubbard physics and sampling problems with programmable initial configurations. This work further defines a route toward native multi-qubit gates and the production of tunable graph states relevant for quantum error correction codes. |
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F01.00116: Towards spin squeezing in a two-dimensional dipolar spin system Weijie Wu, Emily J Davis, Bingtian Ye, Simon Meynell, Lillian Hughes, Zilin Wang, Francisco Machado, Ania C Jayich, Norman Y Yao Using entangled states to enhance quantum metrology represents an exciting near-term application for NISQ hardware. In particular, spin-squeezed states have been demonstrated to enhance phase resolution beyond the standard quantum limit. Generating squeezed states via unitary evolution traditionally requires all-to-all Ising interactions, whereas native interactions on a variety of platforms are typically local. Recently, squeezing via a broader class of power-law XXZ Hamiltonians has been explored numerically, motivating experimental investigations of squeezing with dipolar interactions. Our platform consists of a two-dimensional hybrid spin ensemble of nitrogen vacancy (NV) and substitutional nitrogen (P1) centers in diamond. The dilute NV probe spins are used to spin-polarize the surrounding P1 ensemble, which subsequently evolves freely under the intrinsic dipole-dipole interaction. Distortions of the P1 spin projection noise alter the decoherence profile of the NV probe spins, allowing a diagnosis of squeezing without sub-shot-noise detection resolution. Because the angular average of the dipolar coefficient is zero in three dimensions, our two-dimensional sample uniquely enables squeezing via native interactions in a solid-state spin ensemble. |
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F01.00117: Control and Entanglement of Rydberg Atom Qubits near a Nanophotonic Device Brandon Grinkemeyer, Paloma Ocola, Ivana Dimitrova, Elmer Guardado-Sanchez, Tamara Dordevic, Polnop Samutpraphoot, Vladan Vuletic, Mikhail Lukin Rydberg atoms in optical tweezers have shown promise as a platform for quantum computing. However, Rydberg atoms lack a natural form of quantum networking and fast readout. Which would increase their prospects for scalability, as well as, their ability to perform in-situ quantum error correction. We investigate the use of an optical interface in the form of a silicon nitride photonic crystal cavity (PCC). In our previous work we have demonstrated fast non-destructive state readout through the PCC and the ability to coherently move entangled atoms from the PCC to freespace. In order to determine the viability of a Rydberg atom PCC interface, we characterize the coherence of Rydberg atoms in the presence of the PCC. We find that the Rydberg atom coherence quickly breaks down when we are closer than 100s of microns from the nanophotonic cavity due to the large charge on the PCC and it's charge fluctuation. However, we can recover coherence through decoupling sequences. These results support further investigation of integrating rydberg atom quantum computers with nanophotonic interconnects. |
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F01.00118: Progress towards quantum transduction in a hybrid mm-wave-optical system Tingran Wang, Aishwarya Kumar, Lavanya Taneja, Mark J Stone, Aziza Suleymanzade, Alexander V Anferov, David Schuster, Jonathan Simon We present a hybrid system for coupling mm-wave and optical photons using Rubidium Rydberg atoms. The primary device is a high-Q, monolithic, superconducting cavity in a 4 K cryostat, crossed with an optical resonator and with optical access to trap and cool atoms at the center. With high quality factors of the mm-wave cavity and the strong electric dipole couplings between Rydberg states, exceptionally high single atom cooperativities are achievable. Here, we present recent developments in the experiment including the observation of mean-field optical nonlinearities due to the mm-wave cavity. We describe the integration of a high power 297 nm ultraviolet laser into the experiment and progress towards quantum transduction using this platform. We also talk about our lab's efforts in the direction of implementing interesting local and non-local hamiltonians with optical Fabry-Perot resonators. |
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F01.00119: Quantum metrology at high pressures using the nitrogen vacancy center Prabudhya Bhattacharyya, Thomas Smart, Yuanqi Lyu, Satcher Hsieh, Wuhao Chen, Bryce H Kobrin, Thomas Mittiga, Chong Zu, Xiaoli Huang, Viktor Struzhkin, Raymond Jeanloz, Norman Y Yao The nitrogen vacancy (NV) center in diamond is a robust and versatile quantum sensor that can be reliably operated over a wide range of temperature (up to 1000 K) and pressure (up to 60 GPa) conditions. Incorporating NV centers into diamond anvils cells provides a powerful technique of in situ sensing with high spatial resolution for exploring the rich landscape of high-pressure phenomena. However, previous work has brought into question the feasibility of NV measurements in the megabar pressure regimes owing to loss of contrast and blue shifting of the NV zero phonon line (ZPL). We show that controlling the application of stress by playing with the crystal orientation can overcome these road blocks and demonstrate continuous wave ODMR measurements at 120 GPa with sensitivity of 0.6 G/√Hz. This work provides a crucial tool for the investigation of high temperature superconductivity in high pressure super hydrides. |
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F01.00120: Entanglement-Enhanced Matter-Wave Interferometer Chengyi Luo, Graham P Greve, Baochen Wu, Vanessa P Koh, James K Thompson Collective cavity-QED systems have succeeded in generating large amounts (as much as 18.5 dB) [1,2] of directly observed entanglement beyond the standard quantum limit (SQL), which sets a fundamental limit on phase resolution for all quantum sensors with unentangled atoms. Here, we demonstrate for the first time a matter-wave interferometer with 1.7(5)dB directly observed metrological enhancement of phase resolution beyond the SQL [3]. With the atoms free-falling inside a high-finesse cavity, the entanglements of the external degrees of freedom are generated through both quantum non-demolition measurements and cavity-mediated spin interactions, with directly observed metrological gain 3.4(1.0)dB and 2.5(6)dB below the SQL respectively. These results open a new path for combining particle delocalization to directly enhance measurement precision, bandwidth, and accuracy or to operate at reduced size. |
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F01.00121: Reducing Rydberg polarizability by microwave dressing Ravikumar Chinnarasu, Juan Camilo Bohorquez, Mark Saffman We have demonstrated reduction of Rydberg state DC polarizability of Cesium atoms in a 77 K environment utilizing microwave field dressing. In particular we aim to reduce the polarizability of 52P3/2 states which have relevant resonances at 5.4 GHz to 51D5/2, compatible with interfacing Rydberg atoms to superconducting resonators in a cryogenic environment. We measure the polarizability of the Rydberg states using magneto optical trap (MOT) loss spectroscopy. Using an off-resonant RF field coupling these two levels we have demonstrated a reduction in DC polarizability of the 52P3/2 of over 80%. Our experimental findings are in agreement with a numerical model of the system developed using the Shirley-Floquet formalism. We also demonstrate that the DC polarizability reduction is highly anisotropic, with near total nulling possible when the DC and dressing fields are aligned. We hope to use these results to stabilize Rydberg resonances against varying DC fields present near surfaces, enabling advancements in the development of hybrid Rydberg atom - superconducting resonator quantum gates. |
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F01.00122: Single-Spin Magnetomechanics with Levitated Micromagnets John D Schaefer, Emma Rosenfeld, Trisha Madhavan, Frankie Fung, Alexis Mulski, Mikhail Lukin Coupling quantum nonlinearities to mechanics is an outstanding challenge in the field of quantum science. Realizing such a system would prove useful for applications in quantum metrology and quantum information. We demonstrate a new levitated system consisting of micromagnets over a type-II superconductor. The magnet's center of mass is shown to be trapped in three dimensions, resulting in modes at more than 10 kHz and quality factors of ~10^6. Additionally, the modes can be tuned by adjusted the conditions of the system before cooldown. We also demonstrate the coupling of the levitated magnet to the spin of a single nitrogen-vacancy center in diamond, ~0.048(2) Hz. This proof-of-principle is the first step towards a spin-mechanics system in coupling regimes relevant for quantum applications. |
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F01.00123: STRUCTURE AND PROPERTIES OF ATOMS, IONS, MOLECULES, AND PLASMAS
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F01.00124: Gradient domain machine learning with composite kernels: improving the accuracy of PES and force fields for large molecules Kasra Asnaashari, Roman Krems Gradient domain machine learning (GDML) is based on kernel models that use derivatives of an unknown function to estimate both the function and its gradients [1]. It is particularly useful for applications that require models of both black-box functions and their gradients, such as, for example, the construction of potential energy surfaces (PES) and force fields (FF) for molecular dynamics simulations. In this work we show that GDML models can be significantly improved by increasing the complexity of model kernels. We combine an algorithm previously developed for enhancing pattern recognition performance of Gaussian process models [2] with the GDML approach to build models that produce more accurate results with less training data [3] than the corresponding GDML models. To illustrate this, we build global PES and FFs for ethanol, uracil, malonaldehyde and aspirin. For aspirin, the model with composite kernels at 1000 molecular geometries produces global 57-dimensional PES and FF with the mean absolute error 0.177 kcal/mol and 0.457 kcal/mol Å-1. [1] Chmiela S, et al., Sci. Adv., 3(5), e1603015 (2017) [2] Duvenaud D, et al., Proc. of the 30th Int. Conf. on Mach. Learn., PMLR 28(3), 1166-1174 (2013) [3] Asnaashari K and Krems R V, Mach. Learn.: Sci. Technol. 3 015005 (2022) |
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F01.00125: Environmental effects on electronic structure of tetrachloroplatinate(II): a computational approach Walter C Ermler, Amanda Trevino Many quantum chemical methods used for large complexes give a limited treatment of electrons due to the computational demand dictated by the number of electrons that must be considered explicitly, especially when considering chemical environment. Such treatments can fail to correlate accurately with spectroscopic data obtained for ground and excited states. Ab initio electronic structure theory using the spin-orbit configuration interaction method is applied in a study of spectral transitions in PtCl42- including environmental effects. In this method electronic wave functions are eigenfunctions of the total angular momentum operator belonging to one of the symmetry types of the molecular double group. PtCl42- is investigated as a charged gas phase complex, a point-charge-neutralized complex, and a pseudopotential-neutralized complex. The use of a whole-atom relativistic effective core potential for the potassium cation provides the most accurate picture of its electronic structure without increasing the complexity of the calculation and its computational demand. |
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F01.00126: Systematic differences between beyond K-shell Compton profiles obtained from QED based S-Matrix doubly differential cross sections and those obtained from electron momentum distribution functions. Larry A LaJohn In this study comparisons are made between Compton profiles (CP) obtained from full Compton photon scattering S-Matrix doubly differential cross section (DDCS) spectra and those obtained from an electron distribution function (ρ) via J(pz)=∫pz ρ(p)pdp, where J represents the CP and pz denotes the component of the bound state electron momentum along the scattering vector. Good agreement between K-shell CP obtained via the two theories resulted for all atoms tested ranging from very light to the heaviest atoms. However it was found that systematic differences between CP from the two theories occurred for beyond K-shell CP, but only around where pz≈0. For ns (n>1) subshell CP, those obtained via S-Matrix had a 6-8% lower magnitude at pz=0 than for those obtained via ρ. Further all np subshell CP generated via ρ were flat on top while those obtained via S-Matrix DDCS had sharp maxima that were about 10-12% greater in magnitude at pz=0, but were in good agreement on either side of the peak. nd and nf CP generated by the two theories were also found to differ around pz ≈0 but were in agreement in the tail regions. The present results suggests that there are significant QED factors that contribute to beyond K-shell CPs not accounted for in CP obtained via ρ. |
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F01.00127: Fine structure excitation of oxygen by impact with atomic hydrogen P. -G. Yan, J. F. Babb
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F01.00128: Dual-comb Spectroscopy of Laser-Induced Plasmas Yu Zhang, Reagan Weeks, Ryan T Rhoades, Seth Erickson, Mark C Phillips, Sivanandan S Harilal, R. Jason Jones Dual-comb spectroscopy (DCS) has found a broad range of applications thanks to its ability to provide high spectral resolution over a broad bandwidth. Many applications are based on quasi-static spectroscopic measurements such as those needed in remote sensing or LiDAR. We have been exploring the use of DCS to perform time-resolved measurements of laser-induced plasmas (LIPs). LIPs are powerful tools for the analysis of solid-state materials. For example, it has been used for forensic investigations and isotopic analysis of nuclear materials. A common spectroscopic technique utilizes emission from the LIPs, often referred to as laser-induced breakdown spectroscopy (LIBS). Emission studies generally probe early times in the plasma evolution and with limited spectral resolution. We first applied DCS to LIPs as a proof of concept to detected trace amounts of Rb and K over 8 THz following a single laser ablation shot, with sufficient resolution to resolve the Rb D2 lines. We present more recent results demonstrating novel approaches for higher time-resolution, and multi-species measurements of ionic and atomic transitions, as well as molecular formation following oxidation of Ce within the plasma plume. The wealth of spectral information from this technique enables the characterization of the time-evolution of constituent number densities and plasma temperatures. We also demonstrate a new approach for the measurement of oscillator strengths, demonstrating assignments to 43 neutral gadolinium transitions. |
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F01.00129: A projection operator approach to charge-state distributions following the beta-Decay of 6He Aaron T Bondy, Gordon W F Drake The beta-decay of helium-6 provides a testing ground in searching for physics beyond the Standard Model, which predicts the kinematics of this decay. A large discrepancy between our theory and experiments at the University of Washington [1] has emerged in the amount of double ionization following beta-decay. The theoretical method utilizes correlated Hylleraas wave functions and is not satisfactory in partitioning the charge states since E > 0 states contain an overlap between the single and double continua. We have developed a projection operator formalism using product states that improves the agreement by a factor of four, but a substantial disagreement remains. We report on our use of delta function matrix elements, using the method pioneered by Drachman [2], to measure the ground-state component of our pseudostates to inform modifications so that E > 0 states are represented more accurately. We propose that boundary conditions at the origin should contain the same information as the asymptotic ones used in collision and photoionization studies. |
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F01.00130: High-accuracy prediction of atomic properties of germanium and a systematic estimation of uncertainty Marten Luit Reitsma, Anastasia Borschevsky The relativistic Fock-space coupled-cluster method1 in combination with the finite-field approach2 was used to calculate electric field gradients and magnetic hyperfine fields for the 4p2 and 4p5s states of germanium. Nuclear dipole and quadrupole moments were determined for isotopes of germanium by combining these calculations with hyperfine parameter measurements at ISOLDE-CERN.3 The effects of different computational parameters were investigated and used to determine the uncertainty on the calculated values. |
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F01.00131: A Model of the Atom's structure Based on Two Entangled Quantum Mechanical Systems Hassan Gholibeigian In a quantum worldview, fundamental Particles (FPs) as the building blocks of the world have three entangled identities in both physical and biological characters: matter, dynamic, and information identities. The first character is matter identity including; mass, energy, and charge. The second character is dynamic identity including; particle-wave motion and spin. And the third character is information potential/identity. The information potential (quantum mind/soul) of the conscious FP gets the necessary information, processes, and defines the next quantum state of the FP as its road map. The information potential of an FP includes four hierarchy qualities; matter, plant, animal, and human that became on and active during the world evolution [Gholibeigian, 2015APS.APR.L1027G]. In this way, it seems that an atom is formed by two entangled wavy-like geometries that interact permanently with each other. The first wavy-like geometry is formed by a quantum mechanical system of the atom’s FPs. The second wavy-like geometry is formed by a quantum mechanical system of the information potentials of those FPs like a 3D hologram with the fractal mechanism. The hologram receives the necessary information for the atom, processes and generates consciousness for the atom’s dynamic motion. |
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F01.00132: The Atom’s Structure Based on the Two Quantum Entangled Wavy-like Geometries Hassan Gholibeigian The quantum system of each fundamental particle (FP) includes an information potential (quantum mind/soul) for receiving and analyzing its necessary information as a road map for leading FP to the next quantum state [Gholibeigian, 2015APS.APR.L1027G]. On the other hand, an atom includes some FPs. Therefore, the structure of the atom can be formed from two nested and quantum entangled wavy-like geometries which interact permanently with each other and arise the atom’s character. Each geometry has its own quantum field. The first geometry includes a quantum field of the all FPs of the atom. The second geometry is a quantum field of the atom’s FPs’ quantum minds like a three-dimensional hologram. This 3D hologram which is the atom’s mind has a quantum coherence, gets the necessary information via its FPs’ mind, processes, deepens via fractals mechanism as a whole, and ultimately generates consciousness as a road map for atoms dynamic motion. This generated consciousness is a quantum mechanical entity that can have an eternal and independent existence. Here, our proposed atom’s model explains the behavior of the two quantum fields. This model leads us to the idea that information can be the fifth dimension of nature in addition to space-time [Gholibeigian, 2017APS.APR.F1038G]. |
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F01.00133: An optical pumping-induced damping of Rubidium Larmor frequency M. M Kim, Sangkyung Lee, Sin Hyuk Yim, JiHoon Yoon We study a transversal spin dynamics considered to be important in optically-pumped alkali atomic magnetometers, specifically a cubic Rb vapor cell exposed under a constant external B-field and a circularly polarized D1-line pumping beam incident perpendicularly to the external field. The transient evolution of the magnetization of Rb during optical pumping exhibits a lowered frequency compared to the Larmor frequency ?B, which indicates a damping effect induced by optical pumping. This phenomenon is measured under various intensities of the optical pumping beam and various temperatures of the cell. The effect can partly be explained by analyzing the density matrix equation of the system. |
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F01.00134: Monte Carlo Simulations of X-ray Sources and Nano-moieties for Radiation Therapy and Diagnostics (Theranostics) Alburuj R Rahman, Max Westphal, Anil K Pradhan X-ray therapy and diagnostics devices generate broadband radiation that is not efficient over the entire range and is eiher tool low or too high in energy. Monochromatic or quasi-monochromatic devices may target specific atomic features in high-Z nanoparticles that may absorb radiation more efficiently. We simulate the X-ray-nanoparticle interactions using a modified version of the general purpose Monte Carlo code GEANT4-DNA to compute single-strand-breakups (SSB) and double-strand-breakups (DSB) to demonstrate the efficacy of X-ray radiosenstization of varioius combination of nano-moiteties such as gold nanoparticles. |
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F01.00135: The structure and shape of the Electron Gh. Saleh Normal matter is made of molecules, which are themselves made of atoms. Inside the atoms, there are electrons spinning around the nucleus. The nucleus itself is made of protons and neutrons. Even these particles which we called them subatomic particles are composite objects. |
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F01.00136: Study on angular time delay of e-C60 elastic scattering Aiswarya R, Jobin Jose The time delay in the photoionization and electron scattering attracted the attention of researchers recently [1,2]. Study of time delay on electron elastic scattering allows to characterize the system in temporal domain. The time delay in electron collision depends on both scattering angle θ and scattered electron energy E [3,4]. In this work, we plan to investigate the angular time delay of e-C60 scattering using partial wave methodology [5]. Two different model potentials are used to simulate the environment of C60 shell: Annular Square Well (ASW) and Gaussian Annular Square Well (GASW) [6,7]. Angular time delay for resonant as well as non-resonant scattering is investigated for both the model potentials and the results are compared. |
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F01.00137: ULTRAFAST AND STRONG FIELD PHYSICS
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F01.00138: Spectrum and Carrier Envelope Phase Dependence of High-order Harmonics in Bulk and Thin Film ZnO Christian A Cabello, Yangyang Liu, Troie Journigan, S. Novia Berriel, Michael Chini, Parag Banerjee High order harmonic generation(HHG) in solids has been proposed as a way to measure band structure, study electron dynamics in solids, and produce attosecond pulses. However, this requires a detailed understanding of the microscopic electron dynamics underlying HHG in solids, which can be obscured by nonlinear propagation effects due to propagation in the bulk crystal. Here, we compare the carrier envelope phase(CEP) dependence and harmonic spectra of HHG in bulk and thin film ZnO using few cycle, mid-infrared pulses. We demonstrate that for a beam incident on both the a-plane and c-plane of the bulk ZnO, the harmonics give a clear CEP dependence consistent with the crystal symmetry. The thin film however showed only a weak and qualitatively different CEP dependence which can be explained using perturbative nonlinear optics. These results are in agreement with previous studies of HHG in bulk crystals, and indicate that nonlinear propagation has a significant impact on the CEP dependence in HHG in addition to the spectral and polarization properties of the emitted harmonics. |
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F01.00139: Time-resolved wavelength-dependent excited-state dynamics of diiodomethane Anbu S Venkatachalam, Huynh Van Sa Lam, Enliang Wang, John Searles, Zane Phelps, Artem Rudenko, Daniel Rolles We investigate the time-dependent excited-state dynamics of diiodomethane (CH2I2) induced by variable-wavelength UV light using a UV-IR pump-probe scheme. The tunable UV pump pulse generated from an optical parametric amplifier (OPA) allows us to study the wavelength-dependent effects in a broad range (266nm – 330nm) of the UV spectrum. Strong-field Coulomb explosion imaging performed in a multi-ion coincidence mode using a velocity map imaging spectrometer gives detailed information about the processes. The dissociation dynamics and vibrational-mode motion, e.g., the scissor movement of the I-C-I angle, are reflected in the delay-dependent kinetic energy release (KER) spectra and angular distributions. |
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F01.00140: Probing the Photoemission Delay in Single-Photon Double Ionization Erik Isele, Taran Driver, Siqi Li, Philipp Rosenberger, Joseph Duris, Matthias Kling, Agostino Marinelli, James Cryan X-ray free-electron laser (XFEL) facilities, which produce light pulses with attosecond scale duration, enable the exploration of multi-body interactions on ultrafast timescales. Combining these novel x-ray pulses with circularly polarized infrared laser pulses enables precision timing of photoemission phenomena. We investigate the retardation of valence photoelectrons released via single-photon, double ionization compared to direct ionization of core-level electrons in a neon target. Non-sequential ionization is mediated by electron correlation interactions; thus, we directly probe the timescale for electronic correlations. We use a novel covariance mapping technique to analyze the angular streaking data to suppress the effect of noise in our photoemission measurement. |
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F01.00141: Ghost Imaging Approach to Photon Energy Resolved Velocity Map Imaging Jun Wang, Taran Driver, Felix Allum, Christopher Passow, Christina Papadopoulou, Günter Brenner, Siqi Li, Stefan Düsterer, Atia Tul Noor, Sonu Kumar, Philip H Bucksbaum, Benjamin Erk, James P Cryan, Ruaridh Forbes Correlating measurements of x-ray observables with properties of the incident beam is a powerful approach to improving measurements with noisy x-ray free electron laser (XFEL) sources. In particular, spectral-domain ghost imaging techniques can facilitate sub-bandwidth resolution in spectroscopic measurements at XFELs, greatly enhancing the scope of time-resolved x-ray absorption and photoelectron studies. Time-resolved experiments using velocity map imaging (VMI) spectrometers also face the limitation of broad bandwidth fundamentally linked to the requisite time-resolution. Here we present a novel approach that combines photon spectrum correlation analysis with the reconstruction of three-dimensional momentum distribution from velocity map images in an efficient, single-step procedure. We demonstrate its efficacy with results on the photoelectron spectra of Argon (Ar 2p) and CS$_{2}$ (S 2p) using the CAMP VMI spectrometer at beamline BL1 of the free-electron laser FLASH. Distinct features are observed despite having splittings that are exceeded by the average bandwidth of the ionizing XFEL pulses. As high-resolution photoelectron spectrum is informative about local chemical environment, our approach can be a powerful tool for studying dynamics in molecular systems. |
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F01.00142: Investigating dissociation pathways in photoinduced NO abstraction from nitrobenzene via electron diffraction Kareem Hegazy, Monika Williams, Renkai Li, Ming-Fu Lin, Brian Moore, Pedro Nunes, Xiaozhe Shen, Stephen Weathersby, Xijie Wang, Jie Yang, Thomas J Wolf Nitrobenzene has a rich and complex photochemistry, which is, however, not well understood. In particular, the photochemical NO abstraction has been thought to undergo a roaming style reaction. Such roaming mechanisms are thought to be an important unimolecular reaction where the fragments “roam” around each other before they react and reorganize. Here we directly observe the time dependent structural evolution of gas phase nitrobenzene pumped with 266 nm light at the SLAC Ultrafast Electron Diffraction facility, with 0.5 Å and 150 fs spatial and temporal resolution, respectively. As the first sub-picosecond geometric probe of nitrobenzene’s dynamics we investigate how its nuclear structure changes as the molecule undergoes its complex photochemical dynamics. We find that nitrobenzene quickly relaxes to the ground state within the first picosecond, indicating that subsequent dissociations are thermally driven and take place in the singlet state. |
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F01.00143: Time resolved photoelectron study of excited state dynamics of gas phase thiocytosine Bijay Duwal, Sarita Shrestha, Susanne Ullrich Sulfur substitution of an oxygen atom in the canonical nucleobases disables ultrafast internal conversion pathways back to the ground state and instead triplet states are populated with high quantum yields. The stabilization of electronically excited states with sulfur localized orbital transitions results in easily accessible crossing points to the triplet manifold and intersystem crossing becomes efficient due to strong spin orbit coupling. To date, studies into the photophysics of thiobases have primarily focused on thiocarbonyl compounds. Thiocytosine is a thionated derivative of cytosine that purely exists in its thiol form in the gas phase. The present study employs time-resolved photoelectron spectroscopy to investigate the excited state dynamics of thiocytosine. It shows efficient intersystem crossing despite the absence of the thiocarbonyl group and thereby demonstrates the photophysics of a thiobase from a new tautomer perspective. |
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F01.00144: Internal conversion and intersystem crossing dynamics of doubly thionated Uracil upon photoexcitation at the first and second absorption band Abed Mohamadzade, Irene Conti, Artur Nenov, Marco Garavelli, Susanne Ullrich 2,4-dithiouracil (2,4DTU) has an absorption spectrum extending from the UV-C to UV-A and, upon photoexcitation, undergoes internal conversion (IC) and intersystem crossing (ISC), leading to a population of the triplet state with near-unity quantum yields. The first and second regions of 2,4DTU align with 4TU and 2TU, respectively, which raises the question of whether selective excitation of one of the 2,4 DTU bands results in photodynamics resembling those of the corresponding singly thionated uracil. We use time-resolved photoelectron spectroscopy and ab initio calculations to investigate this question. A 376nm pump wavelength excites the 1??S4??* which internally converts to the lower 1nS4??* state and then populates the 3??S4??*. At 267nm, we observe a much faster process which, in conjunction with theory, reveals a different story. The photoelectron spectrum shows the initial involvement of two states, 1??S2??*’ and 1??S4??*’, which means two parallel decay routes contribute to the relaxation dynamics. However, both evolve to the 1nS2??*’ state and eventually the 3??S2??*’. For 376 nm, we, therefore, conclude that the excited state pathway remains localized on S4 (sulfur in position 4) orbitals and resembles 4TU. On the other hand, deactivation following 267nm excitation involves states with S2 (sulfur in position 2) localized orbitals. Therefore, the faster IC and ISC observed at 267nm could be explained by a switch in the relaxation pathway rather than excess vibrational excitation. |
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F01.00145: Strong-field dynamics of finite-dimensional solids monitored by attosecond transient absorption spectroscopy Stefano M Cavaletto, Lars Bojer Madsen In solids of finite dimension driven by intense NIR pulses, the edge states adjacent to the valence and conduction bands have been shown to decisively impact the resulting strong-field dynamics, with observable features in the emitted HHG spectrum [1]. Here, we investigate the signatures of these strong-field dynamics in the attosecond transient absorption spectrum, when an XUV or x-ray pulse, suitably delayed from the NIR pulse, is used to monitor the evolution of the system. We employ time-dependent density functional theory to simulate the strong-field dynamics undergone by the finite-dimensional solid and identify features in the spectrum associated with edge states. |
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F01.00146: Exploring correlation, nondipole, and propagation time effects of high-order harmonic generation in solids. Simon Vendelbo Bylling V Jensen, Hossein Iravani, Lars Bojer Madsen We consider high-order harmonic generation (HHG) in solid and nanoscale systems. The significance of laser-induced correlation effects is studied with time-dependent density functional theory on a linear chain model of a generic band gap material [1,2]. Certain regimes are identified, where these effects may alter the harmonic yield by an order of magnitude. We give a guideline for identifying such regimes, as well as regimes where such effects are negligible. |
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F01.00147: Applying Ghost Imaging x-ray photoelectron spectroscopy to study the electronic structure of the biologically significant molecule PENNA Kurtis D Borne, Enliang Wang, Taran Driver, Jun Wang, Xinxin Cheng, Andrei Kamalov, Siqi Li, Xiang Li, Ming-Fu Lin, Razib Obaid, Thomas J Wolf, Anbu Venkatchalam, James P Cryan, Peter Walter, Artem Rudenko, Daniel Rolles We demonstrate the use of the spectral-domain ghost imaging technique to study electron structure of 2-phenylethyl-N,N-dimethylamine (PENNA), a biologically significant molecule due to functioning as a neurotransmitter precursor. This method correlates the single-shot x-ray and photoelectron spectra to reconstruct the spectral response of the molecule with sub bandwidth resolution. We show that we can distinguish the chemical shift of the nitrogen 1s orbital in a mixture of molecular nitrogen and PENNA. We apply this technique to time-resolved measurements in UV ionized PENNA to observe charge transfer between the amine and phenyl groups. |
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F01.00148: High resolution FFT spectroscopy of spin-rotation wavepackets in N2+ following strong-field ionization Tomthin Nganba Wangjam, Huynh Van Sa V Lam, Vinod Kumarappan When nitrogen molecules are ionized by femtosecond pulses at 800 nm, post-ionization coupling launches wavepackets in several low-lying cationic states. We probe these bound-state wave packets using a dissociative third harmonic probe and use FFT spectroscopy to identify the states involved with rotational resolution. We find broad rotational excitation in the three lowest cationic states. The coupling of spin and electronic angular momentum to rotational angular momentum is also apparent over the 200 ps scan. We also isolate the momentum distributions from specific two-state rotational coherences to understand the role of rotational motion in the dissociation process. |
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F01.00149: Fifth-force search with isotope-shift spectroscopy in Yb+ Diana Prado Lopes Aude Craik, Joonseok Hur, Eugene Knyazev, Ian T Counts, Luke A Caldwell, Calvin Leung, Swadha Pandey, Julian C Berengut, Amy Geddes, Witold Nazarewicz, Paul-Gerhard Reinhard, Akio Kawasaki, Honggi Jeon, Wonho Jhe, Vladan Vuletic We present our latest results in a spectroscopic search for new physics by measuring isotope shifts in ytterbium ions. Isotope shifts, when measured on at least two atomic transitions can be displayed in a “King plot”. The presence of nonlinearities in such a plot indicates the existence of effects beyond the expected first-order standard model (SM) contributions to the isotope shifts. We have measured isotope shifts on a highly forbidden 467nm octupole transition in five spinless isotopes of Yb+ and, by combining our data with our previous measurements on quadrupole transitions of the same ion and with recent measurements by other groups on a further two transitions in neutral Yb, we find a King nonlinearity with up to 240σ confidence. Furthermore, we determine, with 4.3σ confidence, that this nonlinearity originates from two distinct physical effects. We identify the main source of nonlinearity as originating from as differences in the 4th nuclear charge moment between isotopes, a higher-order nuclear effect that had not previously been measured with high precision. We discuss possible sources of the second nonlinearity and find that it likely cannot be explained by the expected next largest SM contribution. |
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