Phys.org September 2, 2024
Thermalization of radiation by contact to matter is a well-known concept, but the application of thermodynamic methods to complex quantum states of light remains a challenge. Researchers in Germany observed Bose-Einstein condensation of photons into the hybridized ground state of a coupled four-site ring potential. They realized the periodically closed ring lattice superimposed by a weak harmonic trap for photons inside a spatially structured dye-filled microcavity. Photons thermalized to room temperature, and above a critical photon number macroscopically occupied the symmetric linear combination of the site eigenstates with zero phase winding, which constituted the ground state of the system. They verified the mutual phase coherence of photons at different lattice sites by optical interferometry… read more. TECHNICAL ARTICLE
Experimental scheme of dye-filled optical microcavity formed by a microstructured and a plane mirror… Credit: Phys. Rev. Lett. 133, 093602, 30 August 2024