SAMOP 2023 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

Q: Fachverband Quantenoptik und Photonik

Q 42: Poster III

Q 42.16: Poster

Wednesday, March 8, 2023, 16:30–19:00, Empore Lichthof

Open-system dynamics and fluctuation-dissipation relation in a photon Bose-Einstein condensate — •Aleksandr Sazhin¹, Göran Hellman¹, Fahri Emre Öztürk¹, Frank Vewinger¹, Johann Kroha², Vladimir Gladilin³, Michiel Wouters³, Martin Weitz¹, and Julian Schmitt¹ — ¹Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, D-53115 Bonn — ²Physikalisches Institut, Universität Bonn, Nussallee 12, D-53115 Bonn — ³TQC, Universiteit Antwerpen, Universiteitsplein 1, B-2610 Antwerpen

The tuneable openness of optical quantum gases, as photon or polariton condensates in optical microcavities, enables the exploration of new system states and phases, which would not be accessible under closed system conditions. Here, we experimentally demonstrate a non-Hermitian phase transition in a photon Bose-Einstein condensate in an open dye-filled optical microcavity. The transition separates a phase of biexponential photon number correlations from both lasing and an intermediate, oscillatory regime, as characterised by the second-order correlation dynamics of the BEC [1]. By studying the magnitude of the condensate number fluctuations and relating them to a response function, we verify a fluctuation-dissipation relation for the BEC coupled to a molecular reservoir [2]. In more recent work, we have extended these studies to the time domain, establishing a connection between the fluctuation dynamics and the response of the condensate population to an external pulse-like perturbation of the molecular reservoir. [1] F. E. Öztürk et al., Science 372, 88 (2021) [2] F. E. Öztürk et al., arXiv:2203.13255 (2022)