Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 90: Poster Session: Quantum information systems; Optical properties; Ultrafast phenomena

HL 90.9: Poster

Donnerstag, 14. März 2013, 16:00–20:00, Poster A

Interferometric measurements of luminescence from Bose-Einstein condensates of trapped excitons in Cu₂O — •Maria Kaupsch, Rico Schwartz, Frank Kieseling, Gerd Rudlof, and Heinrich Stolz — Institut für Physik, Universität Rostock, D-18051, Rostock, Germany

Recent measurements of the luminescence from Cu₂O at ultra low temperatures show strong evidences of an excitonic Bose-Einstein condensation (BEC) [1,2]. One direct proof of the BEC is the spatial coherence of the luminescence. First measurements were realised with a Michelson interferometer, whereby the image is superimposed with the flipped one. The measurements were made at different cw-excitation powers and temperatures. We observe a rather complicated interference pattern, which depends critically on the optical delay. The results already support the assumption that the luminescence differs from that of a thermal light source. There are also first theoretical approaches for describing the imaging interferometry of ultracold exciton gases [3] which stress the importance of maximum spatial resolution. We discuss first experiments using an aspheric lens close to the Cu₂O sample inside the mixing chamber of the used ³He/⁴He dilution cryostat.

[1] R. Schwartz, N. Naka, F. Kieseling, and H. Stolz, New J. Phys, 14, 023054 (2012); [2] H. Stolz, R. Schwartz, F. Kieseling, S. Som, M. Kaupsch, S. Sobkowiak, D. Semkat, N. Naka, Th. Koch, and H. Fehske, New J. Phys. 14, 105007 (2012); [3] D. Semkat, S. Sobkowiak, G. Manzke, and H. Stolz, Nano Lett. 12, 5055 (2012)