Stuttgart 2012 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 54: Poster 3
Q 54.77: Poster
Donnerstag, 15. März 2012, 16:30–19:00, Poster.I+II
Quantum interference and entanglement of photons which do not overlap in time — Ralph Wiegner1, Christoph Thiel1, •Johannes Hölzl1, Joachim von Zanthier1, and Girish Agarwal2 — 1Institut für Optik, Information und Photonik, Universität Erlangen-Nürnberg, Erlangen — 2Department of Physics, Oklahoma State University, Stillwater, USA
Since the celebrated work of Hong-Ou-Mandel [1] the interference of two independent photons at a beam splitter has been studied in various experiments. To observe the interference the photons have to be identical in their spectral, spatial and polarization modes and measured within their coherence time. However, the temporal overlap of photons at a beam splitter is not a fundamental requirement for the observation of two-photon interferences. Here we discuss a different interferometer where the photons are scattered from two independent single photon sources and registered by two detectors in the far field [2]. It is shown that two-photon interferences occur in this setup even though the time delay between the photons may be larger than the transit time of the photons from the sources towards the detectors. This is equivalent to the statement that two-photon interferences can be observed even though the photons exist at different intervals of time. Since the two-photon signal violates Bell's inequalities this implies that entanglement among two photons may arise even though the photons do not overlap in time.
[1] C. K. Hong, Z. Y. Ou, L. Mandel, PRL 59, 2044 (1987). [2] R. Wiegner et al., Opt. Lett. 36, 1512 (2011).