A. RANCON “Many-Body Dynamical Localization and effective thermalization of a kicked Bose gase”

Adam Rançon, Laboratoire PhLAM, Université de Lille

Dynamical localization is the quantum chaos analog of the Anderson localization of disordered systems, but in momentum space. Interactions tend to destroy localization, but strong enough disorder gives rise to Many-Body Localization (MBL), a phase of matter that has been observed experimentally in cold atoms.
Here we discuss the effect of interactions on a one-dimensional kicked Bose gas in the strong interaction limit (Tonks regime), and show that dynamical localization is not destroyed by the interactions, in the sense that the energy of the system stays finite at long times.
We show that this steady-state is ergodic, i.e. described by a thermal density matrix, with an effective temperature that depends on the kicking parameters and the number of particles. This is in stark contrast with standard MBL. The one-body reduced density matrix of the gas decays exponentially at large distance, implying absence of coherence, while the momentum distribution’s tail at large momenta is characterized by an effectively thermal Tan contact.