Bulletin of the American Physical Society
51st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 65, Number 4
Monday–Friday, June 1–5, 2020; Portland, Oregon
Session M06: Cold Rydberg Gases and PlasmasLive
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Chair: Tom Gallagher, University of Virginia Room: E141-142 |
Thursday, June 4, 2020 8:00AM - 8:12AM Live |
M06.00001: Anderson localization in a Rydberg composite Matthew Eiles, Alex Eisfeld, Jan Michael Rost We demonstrate the localization of a Rydberg electron in a Rydberg composite, a system containing a Rydberg atom coupled to a structured environment of neutral ground state atoms. This localization is caused by weak disorder in the arrangement of the atoms and increases with the number of atoms $M$ and principal quantum number $\nu$. We develop a mapping between the electronic Hamiltonian in the basis of degenerate Rydberg states and a tight-binding Hamiltonian in the so-called "trilobite" basis, and then use this concept to pursue a rigorous limiting procedure to reach the thermodynamic limit in this system, taken as both $M$ and $\nu$ become infinite, in order to show that Anderson localization takes place. This system provides avenues to study aspects of Anderson localization under a variety of conditions, e.g. for a wide range of interactions or with correlated/uncorrelated disorder. [Preview Abstract] |
Thursday, June 4, 2020 8:12AM - 8:24AM Live |
M06.00002: Rydberg molecules induced by high angular momentum electron-perturber interactions Panagiotis Giannakeas, Matthew T Eiles, Francis Robicheaux, Jan-Michael Rost The composite system of a Rydberg atom in the presence of a neutral one is investigated. Going beyond previous studies, we developed a theoretical framework based on the generalized local frame transformation theory which allows us to include higher partial wave interactions of the Rydberg electron with the neutral atoms, which yields additional molecular potential energy curves. These new potential curves give rise to a new family of Rydberg molecules on top of trilobite and butterfly ones. In addition, we demonstrated that these potential curves possess exotic properties, such as their support of a quasi-heavy Rydberg series which are attached to every electronic Rydberg manifold. Also, we study the influence of these new potential curves on the trilobite and butterfly curves and we observed that yield corrections of the order of a few percent for a given electronic Rydberg manifold. [Preview Abstract] |
Thursday, June 4, 2020 8:24AM - 8:36AM Live |
M06.00003: Electromagnetically-induced transparency with Cu$_2$O Rydberg excitons in the presence of phonon coupling Valentin Walther, Peter Gruenwald, Thomas Pohl Rydberg excitons in Cu$_2$O have emerged as a platform of strongly interacting atom-like particles with great potential for both fundamental phenomena as well as optical applications. A central problem is a strong absorptive background underlying the spectrum, stemming from the excitons' coupling to optical phonons and constricting the effect of exciton interactions. Here, we analyze how and under which conditions electromagnetically-induced transparency (EIT) can suppress this background. We investigate the optical response in two-photon absorption as a function of yet unknown system parameters. Depending on these parameters, the background and exciton spectrum can partially or even fully be separated, essentially switching off the coupling to the phonon dynamics. This procedure also provides a direct handle on the experimental determination of these quantities and places limits required for optical applications. Our findings pave the way for the exploitation of Rydberg blockade with Cu$_2$O excitons in EIT setups. [Preview Abstract] |
Thursday, June 4, 2020 8:36AM - 8:48AM Live |
M06.00004: Slow Decay Processes of Electrostatically Trapped Nitric Oxide Rydberg Molecules Stephen Hogan, Adam Deller, Matthew Rayment The large static electric dipole moments associated with high Rydberg states of atoms and molecules make samples in these states amenable to deceleration and electrostatic trapping using inhomogeneous electric fields. In this talk we will describe experiments in which these methods of Rydberg-Stark deceleration have been implemented for the first time to control the motion of nitric oxide (NO) molecules initially traveling in pulsed supersonic beams. In this work the molecules were prepared in long-lived Rydberg-Stark states, with static electric dipole moments of up to 7000 D, by resonance-enhanced two-color two-photon excitation from the ground state. They were then loaded into the traveling electric traps of a chip-based Rydberg Stark decelerator. While confined in these traps the molecules were decelerated from 800 m/s to rest in the laboratory-fixed frame of reference in a time of ~250 $\mu$s and over a distance of 105 mm. The trapped molecules were detected in situ in the decelerator by pulsed electric field ionization. Measurements of the decay of the molecules from the traps over timescales of up to 1 ms, performed with the decelerator operated at 295 K and at 30 K provide new insight into the slow decay processes of long-lived Rydberg states of NO. [Preview Abstract] |
Thursday, June 4, 2020 8:48AM - 9:00AM Live |
M06.00005: Ultrafast electron cooling in an expanding ultracold micro-plasma Juliette Simonet, Tobias Kroker, Mario Neundorf, Markus Drescher, Klaus Sengstock, Philipp Wessels-Staarmann Strong-field ionization of a quantum gas by ultrashort laser pulses allows creating electrons and ions with tunable excess energy. A single femtosecond laser pulse focused to a micrometer-sized waist can ionize up to several thousand atoms out of a Bose-Einstein condensate, thus triggering the formation of strongly coupled ultracold plasmas. We report on the observation of electron cooling in an expanding micro-plasma from initially 5000 K electron temperature to about 1 K within a few hundred nanoseconds. Our experimental setup grants access to the electronic kinetic energy distribution with meV resolution. Furthermore, we have performed numerical simulations of the collective Coulomb driven plasma dynamics which are in excellent agreement with the measurements. The simulations reveal an efficient energy transfer to the ionic system within the first ten picoseconds. [Preview Abstract] |
Thursday, June 4, 2020 9:00AM - 9:12AM Live |
M06.00006: Thermalization in strongly coupled dual species plasma expansions Tucker Sprenkle, Ross Spencer, Scott Bergeson We report measurements of ion temperature evolution in a dual-species ultracold neutral plasma. The plasma is created by photo-ionizing laser-cooled Yb and Ca atoms in a MOT. As this strongly-coupled plasma expands, we use spatially-resolved imaging to measure the expansion velocity, density, and ion temperature as a function of time. The plasma reaches a partial thermal equilibrium, depending on the relative Ca/Yb density ratio. We compare our measurements with a 1D radial fluid code and find significant discrepancies in the temperature and density evolution. [Preview Abstract] |
Thursday, June 4, 2020 9:12AM - 9:24AM Live |
M06.00007: Rydberg Dressing in Optical Tweezer Arrays Nikolaus Lorenz, Lorenzo Festa, Lea Steinert, Philip Osterholz, Robin Eberhard, Christian Gross Neutral atoms in microtrap arrays brought to interaction by Rydberg coupling offer a novel platform to study quantum magnetism. We have constructed a new experiment with potassium atoms, which aims to induce the magnetic interactions via near-resonant Rydberg coupling, so called Rydberg dressing. Here we report on coherent Rydberg coupling in a two dimensional array of single atoms. We observe fast coherent Rabi oscillations of single atoms as well as of small Rydberg superatoms. Finally we discuss first experiments towards Rydberg dressing induced interactions among atomic ground states. [Preview Abstract] |
Thursday, June 4, 2020 9:24AM - 9:36AM On Demand |
M06.00008: Off-resonant radiofrequency heating of ultracold plasmas with weakly and extremely magnetized electrons John Guthrie, Puchang Jiang, Jacob Roberts We have developed an experimental technique to measure the electron temperature increase in ultracold plasmas caused by off-resonant radiofrequency (RF) heating. This heating rate is determined by electron-ion interactions and so can be used to test theories that predict the strength of those interactions. These measurements have been conducted at both low (weak) and high (extreme) degrees of electron magnetization to measure the impact of magnetization on electron-ion interactions. Despite applying strong enough magnetic fields that the electron gyroradius was the dominant length scale in the system, the RF heating rate was unaffected at the 20\% precision level. These experimental results can be used to determine the magnetic field dependence of required cutoff parameters in linear response theories. [Preview Abstract] |
Thursday, June 4, 2020 9:36AM - 9:48AM On Demand |
M06.00009: Time-dependent response of vapor-cell Rydberg EIT in pulsed optical and RF fields Rachel Sapiro, Georg Raithel, David Anderson We investigate the time dependence of atom-light and atom-RF field interactions in Rydberg electromagnetically-induced transparency (EIT) in a room temperature and heated vapor cell. Quantum-optical transients are observed with rapid onset and dissolution of EIT induced by coupler-light pulses. The formation and dissolution time of the transient EIT regime, and its dependencies on light intensity and Rydberg-atom density are studied. Simulations of pulsed EIT are performed by solving a time-dependent three-level master equation with mean-field level-shift corrections, and averaging over the Maxwell velocity distribution in the cell. The results are in excellent agreement with experimental observations, including accurately reproducing quantum-optical transients observed at both onset and dissolution. Time-dependent responses of EIT to RF-field pulses are also investigated. [Preview Abstract] |
Thursday, June 4, 2020 9:48AM - 10:00AM |
M06.00010: Laser-Induced Fluorescence Imaging of Magnetized Ultracold Neutral Plasmas Grant Gorman, MacKenzie Warrens, Thomas Killian Ultracold neutral plasmas (UNPs), created by photoionization of a cold gas, are an excellent tool for studying strongly coupled plasmas, in which the ratio of the nearest neighbor Coulomb energy to the average thermal energy, $\Gamma_i$, is greater than one. Magnetized UNPs are of current interest because of the interplay of magnetization and strong coupling, connection to plasma confinement, and modification of recombination dynamics in strong fields; however, magnetization of UNPs also complicates the use of laser-induced-fluorescence (LIF) images of the ions to extract spatially-resolved density and temperature measurements. Here, we use combined molecular-dynamics and quantum-trajectories (MDQT) simulations to understand the impact that collisions and optical pumping has on the LIF spectra. We then use these simulations to validate an empirical model of the LIF spectra and extract spatially-resolved density and temperature measurements of the magnetized UNP. [Preview Abstract] |
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