Séminaire CEMPI

Peter Schlagheck (Université de Liège)

Quantum interference with ultracold bosonic quantum gases

Ultracold bosonic atoms in optical lattices are certainly among the most versatile experimental platforms for performing quantum simulations of interacting many-body physics. They were particularly employed in order to explore thermalization and localization phenomena through time evolution processes following a quantum quench. While many of those phenomena admit a classical understanding in terms of the dynamics of the underlying classical bosonic field theory, quantum tunneling and interference effects beyond this classical correspondence can nevertheless play a significant role in the context of thermalization and many-body localization.  In my talk, I will specifically focus on the manifestation of many-body quantum interference in the time evolution of ultracold bosonic atoms. I shall argue that the phenomenon of coherent backscattering in Fock space can give rise to an appreciable deviation from quantum ergodicity in finite optical lattices that feature microscopically small populations [1]. I shall furthermore show that mesoscopoically populated Bose-Einstein condensates in such lattices exhibit significant enhancements of their return probability to their initial state as compared to a classical Truncated Wigner prediction [2]. Those enhancements arise due to quantum interference effects that are induced by the presence of discrete symmetries as well as by dynamical localization and scars.

[1] T. Engl et al., Phys. Rev. Lett. 112, 140403 (2014).
[2] P. Schlagheck et al., Phys. Rev. Lett. 123, 215302 (2019).