Bulletin of the American Physical Society
49th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 63, Number 5
Monday–Friday, May 28–June 1 2018; Ft. Lauderdale, Florida
Session V02: Hot Topics |
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Chair: Marianna Safronova, University of Delaware Room: Grand A |
Friday, June 1, 2018 10:30AM - 11:00AM |
V02.00001: Quantum liquid droplets in a mixture of Bose-Einstein condensates Invited Speaker: Leticia Tarruell Dilute quantum droplets are clusters of ultra-cold atoms self-trapped by attractive mean-field forces, and stabilized against collapse by the repulsive effect of quantum fluctuations. Despite not falling into the standard van der Waals paradigm, their properties are those of a liquid and reveal beyond mean-field effects in a weakly interacting system. In this talk, I will describe our recent observation of quantum droplets in a mixture of Bose-Einstein condensates and the experimental study of the corresponding liquid-to-gas phase transition [1]. I will also discuss the difference existing between bright solitons and quantum droplets, which from a non-linear optics perspective can be understood as high-dimensional solitons stabilized by a higher order non-linearity due to quantum fluctuations [2]. [1] C. R. Cabrera, L. Tanzi, J. Sanz, B. Naylor, P. Thomas, P. Cheiney, and L. Tarruell, Science 359, 301 (2018). [2] P. Cheiney, C. R. Cabrera, J. Sanz, B. Naylor, L. Tanzi, and L. Tarruell, Phys. Rev. Lett. 120, 135301 (2018). [Preview Abstract] |
Friday, June 1, 2018 11:00AM - 11:30AM |
V02.00002: Two-dimensional electronic spectroscopy of cold, controlled systems Invited Speaker: Frank Stienkemeier The first two-dimensional electronic spectroscopy (2DES) study of cold molecules (sub Kelvin internal temperature) prepared by helium nanodroplet matrix isolation in a molecular beam apparatus is presented. In contrast to experiments in the liquid/solid phase, our approach allows for the preparation of isolated model systems in well-defined initial quantum states and to study their ultrafast dynamics with high (rovibrational) resolution under the influence of a controlled environment. The principle is demonstrated for high-spin Rb$_{2}$ and Rb$_{3}$ molecules synthesized on the surface of superfluid helium nanodroplets which are studied with phase-modulated 2DES combined with photoionization. Our 2DES spectra exhibit unprecedented high resolution: molecular spin-orbit states are clearly distinguished and a striking asymmetry between absorption and emission is observed due to the cold initial molecular states. As an intriguing aspect of system-bath interactions, we observe coherent spin dynamics in Rb$_{2}$ (symmetry-forbidden in the gas phase) and evidence for a spin-driven chemical reaction in Rb$_{3}$ . Both processes have not been reported for these systems before, which confirms the potential of our unique experimental approach. In general, the established combination of 2DES with well-defined model systems exhibiting a controllable coupling to the environment and limited complexity, will allow studying fundamental principles in physics and chemistry and will help to advance theoretical descriptions of multidimensional spectroscopy. Considering the low density in our molecular beam ($\leq10^{7}$ cm$^{-3}$ ), our experimental setup furthermore opens the possibility to expand 2DES to new fields, e.g. ultracold atoms and molecules, trapped ions or size-selected molecular clusters. [Preview Abstract] |
Friday, June 1, 2018 11:30AM - 12:00PM |
V02.00003: Probing many-body dynamics on a Rydberg quantum simulator Invited Speaker: Mikhail Lukin We demonstrate a method for the creation of controlled many-body quantum matter that combines deterministically prepared, reconfigurable arrays of individually trapped cold atoms with strong, coherent interactions enabled by excitation to Rydberg states. Using this approach we realize a programmable Ising-type quantum spin model with tunable interactions and system sizes up to 51 qubits. Within this model, we observe transitions into ordered states that break various discrete symmetries, verify their high-fidelity preparation, and investigate dynamics across the phase transition in large atom arrays. In particular, we observe novel, robust many-body dynamics corresponding to persistent oscillations of the order after a sudden quantum quench. These observations enable new approaches for exploring many-body phenomena and open the door for realizations of novel quantum algorithms. [Preview Abstract] |
Friday, June 1, 2018 12:00PM - 12:30PM |
V02.00004: Neural-Network Quantum States: from Condensed Matter to Quantum Computing Invited Speaker: Giuseppe Carleo Machine-learning-based approaches, routinely adopted in cutting-edge industrial applications, are being increasingly adopted to study fundamental problems in science. Very recently, their effectiveness has been demonstrated also for many-body physics. In this seminar I will present recent applications to the quantum realm. First, I will discuss how a systematic machine learning of the many-body wave-function can be realized. This goal has been achieved in [1], introducing a variational representation of quantum states based on artificial neural networks. This representation can be used to study both ground-state and unitary dynamics, with controlled accuracy. I will then show how a similar representation can be used for applications directly relevant to ultra-cold atoms and quantum computing. In this context, I will discuss both Quantum State Tomography of highly-entangled states [2], and a novel approach for the classical simulation of large quantum circuits [3].\\ \\ [1] Carleo, and Troyer — Science 355, 602 (2017). [2] Torlai, Mazzola, Carrasquilla, Troyer, Melko, and Carleo — Nature Physics (2018). doi:10.1038/s41567-018-0048-5 [3] Jonsson, and Carleo — In preparation (2018) [Preview Abstract] |
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