# Spontaneous condensation of exciton polaritons in the single-shot regime

## TL;DR

This study visualizes the spontaneous formation of exciton polariton condensates in a semiconductor microcavity during single-shot excitation, revealing the influence of the incoherent reservoir on the condensation process and coherence properties.

## Contribution

It provides new insights into the dynamics of polariton condensation by using single-shot imaging, highlighting the role of reservoir depletion and differences between photonic and excitonic polaritons.

## Key findings

- Condensates of photonic polaritons show filamentation and fluctuations.
- Condensates of excitonic quasiparticles are smooth and coherent.
- Reservoir depletion is critical for ground state transition.

## Abstract

Bose-Einstein condensate of exciton polaritons in a semiconductor microcavity is a macroscopically populated coherent quantum state subject to concurrent pumping and decay. Debates about the fundamental nature of the condensed phase in this open quantum system still persist. Here, we gain a new insight into the spontaneous condensation process by imaging long-lifetime exciton polaritons in a high-quality inorganic microcavity in the single-shot optical excitation regime, without averaging over multiple condensate realisations. In this highly non-stationary regime, a condensate is strongly influenced by the `hot' incoherent reservoir, and reservoir depletion is critical for the transition to the ground energy and momentum state. Condensates formed by more photonic exciton polaritons exhibit dramatic reservoir-induced density filamentation and shot-to-shot fluctuations. In contrast, condensates of more excitonic quasiparticles display smooth density and are second-order coherent. Our observations show that the single-shot measurements offer a unique opportunity to study formation of macroscopic phase coherence during a quantum phase transition in a solid state system.