Quantum gases in time-modulated optical lattices: from quantum chaos to quantum control and vice versa (Webinar)

In this talk, I propose to focus on two recent experimental results of our team obtained by shaking a Bose Einstein condensate in an optical lattice:

1) In the first part, I will focus on quasi-resonant modulation of the lattice depth to observe a quantum chaos transport mechanism called chaos-assisted tunneling. Under such a modulation, the classical phase space exhibits  stable islands surrounded by a large chaotic sea. The chain of islands mimics an effective superlattice, with new controllable tunneling properties. The coupling between islands is indeed mediated by delocalized Floquet states that spread over the chaotic sea. As a result, the transport between the islands exhibit sharp resonances where the tunneling rate varies by orders of magnitude over a short range of parameters. We experimentally demonstrate and characterize these resonances for the first time in a quantum system. This opens the way to new kinds of quantum simulations with long-range transport [1,2].

2) In the second part, I will focus the discussion on the production of s-wave scattering halos from collisions between the momentum components of a Bose–Einstein condensate released from an optical lattice. We report on the engineering of those halos through the precise control of the atom dynamics in the lattice: we are able to specifically enhance collision processes with given center-of-mass and relative momenta. In particular, we observe quantized collision halos between opposite momenta components of increasing magnitude [3]. More generally, by a proper driving of the lattice position, we will show our ability to engineer a wide variety of momentum superpositions using optimal control theory.

Bibliography:

[1] M. Arnal, G. Chatelain, M. Martinez, N. Dupont, O. Giraud, D. Ullmo, B. Georgeot, G. Lemarié, J. Billy and D. Guéry-Odelin, Science Advances 6, eabc4486 (2020).

[2] Maxime Martinez, Olivier Giraud, Denis Ullmo, Juliette Billy, David Guéry-Odelin, Bertrand Georgeot, and Gabriel Lemarié, arXiv:2011.02557v1 [quant-ph]

[3] G. Chatelain, N. Dupont, M. Arnal, B. Brunaud, J. Billy, B. Peaudecerf, P. Schlagheck and D. Guéry-Odelin, New Journal of Physics 22, 123032 (2020).