Hannover 2016 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 27: Poster: Quantum Optics and Photonics II
Q 27.13: Poster
Tuesday, March 1, 2016, 16:30–19:00, Empore Lichthof
First order coherence of an ideal Bose gas of light — •Tobias Damm1, Julian Schmitt1, David Dung1, Christian Wahl1, Frank Vewinger1, Jan Klaers1,2, and Martin Weitz1 — 1Institute of Applied Physics, University of Bonn — 2Present address: Institute for Quantum Electronics, ETH Zürich
Bose-Einstein condensation in the gaseous regime has been oberseved with cold atoms, exciton-polaritons and more recently with photons in a dye-filled optical microcavity. The latter system is thermally equilibrated both below and above criticality due to repeated absortion and re-emission processes of the dye molecules.
In this work we report on the measurements of the first order coherence of the photon gas confined in a dye-filled optical microcavity below as well as above the phase transition to a photon condensate. Tunable Michelson and Mach-Zehnder interferometers are used to split up and recombine the cavity emission to obtain temporal and spatial coherence information respectively. The observed coherence times range from sub-picoseconds for noncritical system sizes up to microseconds for condensed systems. While below criticality the coherence length is in the micrometer regime, above criticality phase coherence is established macroscopically over the whole mode volume.