Reinforcement learning in cold atom experiments.

Cold atom traps are at the heart of many quantum applications in science and technology. The preparation and control of atomic clouds involves complex optimization processes, that could be supported and accelerated by machine learning. In this work, we introduce reinforcement learning to cold atom experiments and demonstrate a flexible and adaptive approach to control a magneto-optical trap.

Multiplane Diffractive Acoustic Networks.

Acoustic holograms are able to control pressure fields with high spatial resolution, enabling complex fields to be projected with minimal hardware. This capability has made holograms attractive tools for applications, including manipulation, fabrication, cellular assembly, and ultrasound therapy. However, the performance benefits of acoustic holograms have traditionally come at the cost of temporal control.

Bichromatic state-dependent disordered potential for Anderson localization of ultracold atoms.

Abstract: The ability to load ultracold atoms at a well-defined energy in a disordered potential is a crucial tool to study quantum transport, and in particular Anderson localization. In this paper, we present a new method for achieving that goal by rf transfer of atoms in an atomic Bose-Einstein condensate from a disorder-insensitive state to a disorder-sensitive state. It is based on a bichromatic laser speckle pattern, produced by two lasers whose frequencies are chosen so that their light-shifts cancel each other in the first state and add up in the second state.

Elastic Scattering Time of Matter Waves in Disordered Potentials.

We report on an extensive study of the elastic scattering time τ_{s} of matter waves in optical disordered potentials. Using direct experimental measurements, numerical simulations, and comparison with the first-order Born approximation based on the knowledge of the disorder properties, we explore the behavior of τ_{s} over more than 3 orders of magnitude, ranging from the weak to the strong scattering regime. We study in detail the location of the crossover and, as a main result, we reveal the strong influence of the disorder statistics, especially on the relevance of the widely used Ioffe-Regel-like criterion kl_{s}∼1.

Measurement of Spectral Functions of Ultracold Atoms in Disordered Potentials.

We report on the measurement of the spectral functions of noninteracting ultracold atoms in a three-dimensional disordered potential resulting from an optical speckle field. Varying the disorder strength by 2 orders of magnitude, we observe the crossover from the "quantum" perturbative regime of low disorder to the "classical" regime at higher disorder strength, and find an excellent agreement with numerical simulations. The method relies on the use of state-dependent disorder and the controlled transfer of atoms to create well-defined energy states.

Continuous loading of a conservative potential trap from an atomic beam.

We demonstrate the fast accumulation of 52Cr atoms in a conservative potential from a guided atomic beam. Without laser cooling on a cycling transition, a dissipative step involving optical pumping allows us to load atoms at a rate of 2×10(7)  s(-1) in the trap. Within less than 100 ms we reach the collisionally dense regime, from which we produce a Bose-Einstein condensate with subsequent evaporative cooling.