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

## TL;DR

This paper demonstrates that atom losses in a 1D Bose gas can produce long-lived, non-thermal states with mode-dependent temperatures, linked to the system's integrability, and confirms their robustness through classical and quantum analyses, including experimental evidence.

## Contribution

It reveals the formation of long-lived non-thermal states in 1D Bose gases due to atom losses, highlighting the role of integrability and extending analysis to quantum noise and trapped gases.

## Key findings

- Non-thermal states are formed after atom losses in 1D Bose gases.
- These states are robust and long-lived, even after losses cease.
- Experimental evidence supports the theoretical predictions.

## Abstract

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.