Our team at the University of Bonn together with colleagues from the University of Antwerp and the University of Freiburg have established a fundamental relation connecting the temporal fluctuations and the response behaviour in a quantum gas made of photons, the particles of light. In our experiments, we confirm the validity of the so-called quantum regression theorem, which so far could not be directly revealed for quantum gases. Our findings provide a powerful new tool to probe optical quantum gases in lattices with complex spatial structure or topological properties in the future. The study is published in the journal Nature Communications.
Read the manuscript "Observation of nonlinear response and Onsager regression in a photon Bose-Einstein condensate" here.
For a more general perspective on the study, check out the blog post 'Behind the Paper: Fluctuations and Response in a Quantum Gas of Light" by Andris Erglis and Julian Schmitt.