Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session S07: New Laser Cooling and Trapping Techniques |
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Chair: Toshi Shimasaki, UCSB Room: 206 B |
Thursday, June 8, 2023 10:30AM - 10:42AM |
S07.00001: Design and Commissioning of an Octupole Magneto-optical Trap for Sub-Doppler Cooling of 39K Corbyn D Mellinger, David Loos, Benjamin D DalFavero, Chance Persons, Joe Klomp, Jonathan P Wrubel Potassium has proven to be a difficult atom to Bose-condense, with initial condensates coming about due to sympathetic cooling from other species, e.g. 87Rb. The difficulty with achieving a high phase-space trap is largely due to the hyperfine atomic structure of potassium, with splitting between the 2P3/2 F'=3 and F'=2 levels only 20 MHz (3.3Γ) in 39K and about 17 MHz (2.8Γ) in 41K, preventing the use of dark-spot magneto-optical traps (MOTs). Low density and high photon rescattering make loading a potassium optical dipole trap challenging. Sub-Doppler cooling techniques have been developed for potassium, but dipole trap loading remains inefficient due to the low initial density. |
Thursday, June 8, 2023 10:42AM - 10:54AM |
S07.00002: A bilayer system of dipolar atoms on a 50 nm scale Li Du, Pierre Barral, Michael Cantara, Julius de Hond, Wolfgang Ketterle We implement a new super-resolution technique which arranges magnetic atoms on a sub-50 nm scale --- a scale on which the interatomic dipole-dipole interaction is greatly enhanced. We demonstrate the technique by creating a bilayer system of ultracold dysprosium atoms with tunable interlayer distances. The dipolar interaction between the two layers is observed via the interlayer sympathic cooling and the coupled collective excitations. This technique can be generalized to optical tweezers, and should enable quantum gates driven by magnetic dipole-dipole interactions. |
Thursday, June 8, 2023 10:54AM - 11:06AM |
S07.00003: Strontium Tweezer Arrays via Holographic Metasurfaces Aaron Holman, Weijun Yuan, Ximo Sun, Chun-Wei Liu, Kevin Wang, Xiaoyan Huang, Nanfang Yu, Bojeong Seo, Sebastian Will We present a platform for trapping neutral strontium atoms in optical tweezer arrays generated by holographic metasurfaces. Metasurfaces - flat, nanopatterned optical devices - offer an exciting new avenue for the creation of versatile trapping potentials for cold atom experiments. Metasurfaces are usable in- and outside of vacuum, have a small footprint, and excel in high power capability, enabling large tweezer arrays. We characterize the homogeneity, loading characteristics, and cooling of atoms in these traps. The trap wavelength is at 520 nm, an unexplored magic wavelength for the 1S0 - 3P1 intercombination line of strontium. We demonstrate a diverse set of trapping geometries, such as quasicrystals and twisted bilayer graphene, suitable for applications in quantum simulation and quantum optics. Leveraging the versatile trapping geometries, we are working towards the realization of atomic waveguides, demonstrating super- and subradiance in the atomic emission, which may enable future applications as atomic quantum memories. |
Thursday, June 8, 2023 11:06AM - 11:18AM |
S07.00004: Atom-number enhancement by shielding in a strontium magneto-optical trap Sandra Buob, Jonatan Höschele, Antonio Rubio-Abadal, Vasiliy Makhalov, Leticia Tarruell Atomic strontium has gained popularity over the last years in various fields of quantum science, such as quantum simulation and computation, atomic clocks and atom interferometers. Many of these applications require the preparation of laser-cooled clouds with large atom numbers. In this talk, we report on a method to double the atom number in a strontium magneto-optical trap (MOT) that can benefit existing experiments as it requires no constructional changes. |
Thursday, June 8, 2023 11:18AM - 11:30AM |
S07.00005: Chiral-coupling-assisted refrigeration and superior dark-state sideband cooling in trapped atoms Hsiang-Hua Jen Cooling the trapped atoms toward their motional ground states is key to applications of quantum simulation and quantum computation. Here we demonstrate the capability of light-mediated chiral couplings between atoms, which enables a superior cooling scheme exceeding the single-atom limit of sideband cooling. We present the chiral-coupling-assisted refrigeration in the target atom at the price of heating the others under asymmetric drivings, where its steady-state phonon occupation outperforms the lower bound set by a single atom. By utilizing nonreciprocal couplings between two atoms, we also present an intriguing dark-state cooling scheme in Λ-type three-level structure, which is shown superior than the conventional electromagnetically-induced-transparency cooling in a single atom. Our results present a resource of collective chiral couplings which help surpass the bottleneck of cooling procedure in applications of trapped-atom-based quantum computer and simulator. |
Thursday, June 8, 2023 11:30AM - 11:42AM |
S07.00006: Expansion dynamics of a shell-shaped Bose-Einstein Condensate Zerong Huang, LiYuan Qiu, Chun Kit Wong, Fan Jia, Yangqian Yan, Dajun Wang We report the creation of a shell BEC in the presence of Earth's gravity with immiscible dual-species BECs of sodium and rubidium atoms. After minimizing the displacement between the centers of mass of the two BECs with a magic-wavelength optical dipole trap, the interspecies repulsive interaction ensures the formation of a closed shell of sodium atoms with its center filled by rubidium atoms. Releasing the double BEC together from the trap, we observe explosion of the filled shell accompanied by energy transfer from the inner BEC to the shell BEC. With the inner BEC removed, we obtain a hollow shell BEC that shows self-interference as a manifestation of implosion. Some recent results on the expansion dynamics after quenching the interspecies interaction will also be presented. |
Thursday, June 8, 2023 11:42AM - 11:54AM |
S07.00007: A Single-Wavelength Trap Array of Neutral Rubidium and Cesium Atoms Sam A Norrell, Sam A Norrell, Chengyu Fang, Ravikumar Chinnarasu, Cody A Poole, Arian M Noori, Trent Graham, Sanket Deshpande, Mikhail A Kats, Mark Saffman Neutral atoms trapped in optical lattice arrays provide a promising framework for quantum computation, but crosstalk between individual qubits limits the functionality of such devices. Using multiple atomic species offers potential solutions to many of the issues single-species quantum computers encounter. We present a two-species trap array using a single laser and exclusively passive optical elements. This array operates at reduced cost, space, and alignment overheads compared to tweezer arrays for even single-species operation. |
Thursday, June 8, 2023 11:54AM - 12:06PM |
S07.00008: Detachable 2D MOT Platform as a Cesium Source Towards the Construction of a Quantum Simulator Involving Cesium-Lithium Mixtures Jonathan Yang, Kaiyue Wang, Colin V Parker, Sachin Barthwal In our efforts to construct a Cesium-Lithium (Cs-Li) Bose-Fermi mixture apparatus for quantum simulation experiments, we have constructed a compact 2D magneto-optical trap (MOT) platform which acts as a continuous source of cold Cs atoms. This design requires only one laser output and contains all the optics necessary to split the beam 5 ways into the horizontal and vertical directions with the correct polarizations. This platform is moreover detachable, thus facilitating easier attachment onto the Cs-Li mixture chamber, however, it is currently connected to a test chamber in which a 3D Cs MOT is first loaded. We subsequently increase the detuning and magnetic field gradient to produce a compressed MOT (CMOT), before increasing the detuning even further and removing the magnetic field to generate an optical molasses. After that we load the Cs atoms into an optical lattice and further cool them via a degenerate Raman Sideband Cooling (DRSC). Time-of-flight (TOF) absorption images are utilized to calculate parameters including the temperature, atom number, and density. |
Thursday, June 8, 2023 12:06PM - 12:18PM |
S07.00009: Use of machine learning to maximize loading efficiency of cold cesium atoms into a hollow-core photonic crystal fiber Paul Anderson, Sreesh Venuturumilli, Katie McDonnell, Rubayet Al Maruf, Michal Bajcsy We report the results of a machine-learned algorithm for optimal loading of cold cesium atoms into a hollow-core photonic crystal fiber. Light-matter interactions using atomic ensembles has remained a popular means for quantum communication and quantum memories. However, interacting with single photons using cold atomic ensembles generally requires a large number of atoms within a tightly-focused beam. We accomplish this by inserting cold atoms, prepared in a magneto-optical trap, into a vertical segment of hollow-core fiber using gravity and an attractive dipole beam. The loading efficiency depends on many parameters which dictate the initial position, size, and temperature of the cloud, as well as the time taken to reach the fiber core. Many of these parameters are coupled to one another and performing a full sweep of the parameter space would be time consuming. Thus, the preference is to intelligently scan through the parameter space to find optimal settings within a reasonable timeframe. From here, the machine-learning algorithm M-LOOP was used in conjunction with our experiment control program to maximize the number of atoms loaded inside the fiber. However, the success of the algorithm depends greatly on the feedback received (cost function) accurately represents the end result we desire with minimal uncertainty. Using optical depth requires scanning many detunings to get a single cost function and is very sensitive to probe coupling through the fiber. Instead, we use a method called bleaching where the atom number is determined by counting photons missing from a resonant pulse sent through the fiber. |
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