Quantum radiations from exciton condensate in Electron-Hole Bilayer Systems

TL;DR

This paper investigates the quantum properties of photons emitted from exciton superfluids in electron-hole bilayer systems, revealing unique coherence and squeezing features that distinguish them from other condensed matter emissions.

Contribution

It introduces a detailed theoretical analysis of photon emission from exciton superfluids, highlighting their unique quantum states and providing methods to extract key parameters from experimental data.

Findings

Photons emitted perpendicular to the layer are in a coherent state.

Photons along tilted directions are in a two-mode squeezed state.

Photon bunching and super-Poissonian statistics are observed.

Abstract

Superfluid has been realized in Helium-4, Helium-3 and ultra-cold atoms. It has been widely used in making high-precision devices and also in cooling various systems. There have been extensive experimental search for possible exciton superfluid (ESF) in semiconductor electron-hole bilayer (EHBL) systems below liquid Helium temperature. However, exciton superfluid are meta-stable and will eventually decay through emitting photons. Here we study quantum nature of photons emitted from the excitonic superfluid (ESF) phase in the semiconductor EHBL and find that the light emitted from the excitonic superfluid has unique and unusual features not shared by any other atomic or condensed matter systems. We show that the emitted photons along the direction perpendicular to the layer are in a coherent state, those along all tilted directions are in a two modes squeezed state. We determine the two mode squeezing spectra, the angle resolved power spectrum, the line shapes of both the momentum distribution curve (MDC) and the energy distribution curve (EDC). From the two photon correlation functions, we find there are photon bunching, the photo-count statistics is super-Poissonian. We discuss how several important parameters such as the chemical potential, the exciton decay rate, the quasiparticle energy spectrum and the dipole-dipole interaction strength between the excitons in our theory can be extracted from the experimental data and comment on available experimental data on both EDC and MDC.