Photon-Number-Resolved Measurement of an Exciton-Polariton Condensate

• Published in: Physical review letters Vol. 121; no. 4; p. 047401
• Main Authors: Klaas, M, Schlottmann, E, Flayac, H, Laussy, F P, Gericke, F, Schmidt, M, Helversen, M V, Beyer, J, Brodbeck, S, Suchomel, H, Höfling, S, Reitzenstein, S, Schneider, C
• Format: Journal Article
• Language: English
• Published: United States 27.07.2018
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.121.047401

We measure the full photon-number distribution emitted from a Bose condensate of microcavity exciton polaritons confined in a micropillar cavity. The statistics are acquired by means of a photon-number-resolving transition edge sensor. We directly observe that the photon-number distribution evolves with the nonresonant optical excitation power from geometric to quasi-Poissonian statistics, which is canonical for a transition from a thermal to a coherent state. Moreover, the photon-number distribution allows one to evaluate the higher-order photon correlations, shedding further light on the coherence formation and phase transition of the polariton condensate. The experimental data are analyzed in terms of thermal-coherent states, which gives direct access to the thermal and coherent fraction from the measured distributions. These results pave the way for a full understanding of the contribution of interactions in light-matter condensates in the coherence buildup at threshold.