Dissipation Driven Coherent Dynamics Observed in Bose-Einstein Condensates

TL;DR

This paper reports the first experimental observation of dissipation-driven coherent oscillations in a Bose-Einstein condensate, demonstrating dissipation as a tool to control quantum many-body dynamics.

Contribution

It introduces dissipation as a novel and controllable mechanism to induce and observe coherent quantum oscillations in Bose-Einstein condensates.

Findings

Dissipation causes different atom loss rates in thermal and condensate components.

Dissipation can be used to increase system temperature without density excitation.

Coherent atom exchange leads to observable oscillations in atom numbers.

Abstract

We report the first experimental observation of dissipation-driven coherent quantum many-body oscillation, and this oscillation is manifested as the coherent exchange of atoms between the thermal and the condensate components in a three-dimensional partially condensed Bose gas. Firstly, we observe that the dissipation leads to two different atom loss rates between the thermal and the condensate components, such that the thermal fraction increases as dissipation time increases. Therefore, this dissipation process serves as a tool to uniformly ramp up the system's temperature without introducing extra density excitation. Subsequently, a coherent pair exchange of atoms between the thermal and the condensate components occurs, resulting in coherent oscillation of atom numbers in both components. This oscillation, permanently embedded in the atom loss process, is revealed clearly when we inset a duration of dissipation-free evolution into the entire dynamics, manifested as an oscillation of total atom number at the end. Finally, we also present a theoretical calculation to support this physical mechanism, which simultaneously includes dissipation, interaction, finite temperature, and harmonic trap effects. Our work introduces a highly controllable dissipation as a new tool to control quantum many-body dynamics.