Collective modes of a photon Bose–Einstein condensate with thermo-optic interaction

Enrico Stein,Frank Vewinger,Axel Pelster

doi:10.1088/1367-2630/ab4b06

Enrico Stein, Frank Vewinger + Show 1 more

Open Access

https://doi.org/10.1088/1367-2630/ab4b06

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Abstract

Although for photon Bose–Einstein condensates the main mechanism of the observed photon–photon interaction has already been identified to be of a thermo-optic nature, its influence on the condensate dynamics is still unknown. Here a mean-field description of this effect is derived, which consists of an open-dissipative Schrödinger equation for the condensate wave function coupled to a diffusion equation for the temperature of the dye solution. With this system at hand, the lowest-lying collective modes of a harmonically trapped photon Bose–Einstein condensate are calculated analytically via a linear stability analysis. As a result, the collective frequencies and, thus, the strength of the effective photon–photon interaction turn out to strongly depend on the thermal diffusion in the cavity mirrors. In particular, a breakdown of the Kohn theorem is predicted, i.e. the frequency of the centre-of-mass oscillation is reduced due to the thermo-optic photon–photon interaction.

Highlights

In recent years many theoretical and experimental results have contributed to a basic understanding of quantum fluids of light [1], where many photons propagate in nonlinear optical systems
The corresponding collective features are due to effective photon–photon interactions, which are induced by the nonlinear matter
In contrast to that an equilibrium Bose–Einstein condensate (BEC) of pure light was achieved in Bonn in 2010 [6]

Summary

October 2019

This work must maintain photon interaction has already been identified to be of a thermo-optic nature, its influence on the attribution to the author(s) and the title of condensate dynamics is still unknown. Consists of an open-dissipative Schrödinger equation for the condensate wave function coupled to a diffusion equation for the temperature of the dye solution. With this system at hand, the lowest-lying collective modes of a harmonically trapped photon Bose–Einstein condensate are calculated analytically via a linear stability analysis. The collective frequencies and, the strength of the effective photon–photon interaction turn out to strongly depend on the thermal diffusion in the cavity mirrors.

Introduction

Methods

Steady state

Linearised dynamics

Findings

Summary and experimental perspective