Chaotic walking of a cold atom in an ideal cavity

Victor Yu. Argonov, Sergey V. Prants

Sergey V. Prants

Sergey V. Prants, V. O. Vitkovsky

Sergey V. Prants

Abstract Coherent dynamics of cold atoms in a 2D optical lattice with interfering laser beams is studied with account for internal and external degrees of freedom of an atom. A system of differential equations for coupled degrees of freedom obtained in the semiclassical approximation has regular and chaotic solutions depending on the atomic-field detuning from resonance. The Hamilton chaos is manifested in the form of chaotic Rabi oscillations and random walks of cold atoms in the lattice for relatively small resonance detunings. It is shown that the deterministic chaos appears as a result of jumps in the value of the electric dipole moment of an atom approaching the nodes of a 2D standing wave. This in turn causes a pseudorandom behavior of momenta of atoms and, as a consequence, their random walks in the absolutely rigid 2D optical lattice without any external modulation of its parameters. It is shown in numerical experiments with 106 atoms that their distributions over the lattice for different resonance detunings differ significantly. This fact can be used for detecting the effect of random walks of cold atoms in a real experiment by the absorption image method.

Olivier Leblanc, Loïc Tadrist, Nicolas Moreau +3 more

Walking droplets represent an ideal playground to explore wave-particle duality at the macroscopic scale. The proper control and measurement of such system requires several experimental tools that are not often easily affordable at undergraduate level. This paper proposes a complete low-cost and open-source experimental setup for walking droplets with a performance characterization. The setup is tested by examining the behaviour of droplets in the stadium billiard, a two-dimensional concave cavity that yields chaotic trajectories. Drastic differences between classical and quantum particles behaviour were observed in such geometry. In particular, the long-term evolution of walking droplets in a stadium billiard presents clear scarring patterns, informing on the existence of preferred "probable positions" within the billiard.