Modified Bose-Einstein condensation in an optical quantum gas

TL;DR

This paper explores how controlled dissipation and feedback influence Bose-Einstein condensation in an optical quantum gas, revealing physical mechanisms in non-equilibrium conditions and opening new avenues for quantum simulation.

Contribution

It demonstrates the effects of environment-controlled dissipation and feedback on Bose-Einstein condensation in a photonic gas, providing insights into non-equilibrium quantum phenomena.

Findings

Condensation results from energy minimization, loss reduction, and constructive feedback.

Physical mechanisms of condensate formation are revealed under non-equilibrium conditions.

Experimental results suggest new pathways for quantum simulation with optical condensates.

Abstract

Open quantum systems can be systematically controlled by making changes to their environment. A well-known example is the spontaneous radiative decay of an electronically excited emitter, such as an atom or a molecule, which is significantly influenced by the feedback from the emitter's environment, for example, by the presence of reflecting surfaces. A prerequisite for a deliberate control of an open quantum system is to reveal the physical mechanisms that determine the state of the system. Here, we investigate the Bose-Einstein condensation of a photonic Bose gas in an environment with controlled dissipation and feedback realised by a potential landscape that effectively acts as a Mach-Zehnder interferometer. Our measurements offer a highly systematic picture of Bose-Einstein condensation under non-equilibrium conditions. We show that the condensation process is an interplay between minimising the energy of the condensate, minimising particle losses and maximising constructive feedback from the environment. In this way our experiments reveal physical mechanisms involved in the formation of a Bose-Einstein condensate, which typically remain hidden when the system is close to thermal equilibrium. Beyond a deeper understanding of Bose-Einstein condensation, our results open new pathways in quantum simulation with optical Bose-Einstein condensates.