Long-lived non-thermal states realized by atom losses in one-dimensional quasi-condensates

A. Johnson (1) , S. S. Szigeti (2) , M. Schemmer (1) , Isabelle Bouchoule (1)

1 Laboratoire Charles Fabry / Optique atomique
2 The University of Queensland

We investigate the cooling produced by a loss process non selective in energy on a one-dimensional (1D) Bose gas with repulsive contact interactions in the quasi-condensate regime. By performing nonlinear classical field calculations for a homogeneous system, we show that the gas reaches a non-thermal state where different modes have acquired different temperatures. After losses have been turned off, this state is robust with respect to the nonlinear dynamics, described by the Gross-Pitaevskii equation. We argue that the integrability of the Gross-Pitaevskii equation is linked to the existence of such long-lived non-thermal states, and illustrate this by showing that such states are not supported within a non-integrable model of two coupled 1D gases of different masses. We go beyond a classical field analysis, taking into account the quantum noise introduced by the discreteness of losses, and show that the non-thermal state is still produced and its non-thermal character is even enhanced. Finally, we extend the discussion to gases trapped in a harmonic potential and present experimental observations of a long-lived non-thermal state within a trapped 1D quasi-condensate following an atom loss process.

Domaines: Gaz Quantiques [cond-mat.quant-gas]

A. Johnson, S. S. Szigeti, M. Schemmer, Isabelle Bouchoule. Long-lived non-thermal states realized by atom losses in one-dimensional quasi-condensates. 2017. ⟨hal-01479415v1⟩