Andris Erglis, Alexander Sazhin, Frank Vewinger, Martin Weitz, Stefan Yoshi Buhmann, and Julian Schmitt
Phys. Rev. Lett. 135, 033603 (2025)
🔓 arXiv:2502.14986 (2025)
We study the frequency-resolved density response of a photon Bose–Einstein condensate coupled to a bath of dye molecules by time-periodic driving. By monitoring the photon number dynamics for different drive frequencies, we obtain the spectral response of the condensate in a phase-sensitive way. We find that as the photon number increases, the response of the coupled condensate-bath system transitions from overdamped to resonant behavior, indicating a transition from closed to open system dynamics. Our spectroscopy method paves the way for studies of collective excitations in complex driven-dissipative systems.