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Q: Quantenoptik
Q 323: Quanteneffekte II
Q 323.7: Vortrag
Mittwoch, 6. März 2002, 18:00–18:15, HS 01/E02
A quantum optical test of complementarity with single photons — •Christoph Braig, Patrick Zarda, Christian Kurtsiefer, and Harald Weinfurter — Universität München, Sektion Physik, Schellingstr. 4 (III), 80799 Muenchen
We demonstrate the principle of complementarity in quantum mechanics with true single photon states. In our scheme, single photons are provided by isolated, optically pumped nitrogen-va- cancy centers in diamond, which can be easily adressed by con- focal microscopy. The single photon character is proved by an elementary Hanbury-Brown-Twiss experiment, which yields almost perfect photon antibunching apart from small back- ground contributions. This measurement shows that a single photon will only be detected in one of the two arms when the setup is extended to a Mach-Zehnder interferometer. In contrast, if we dispense this “which path”-information, we get interference fringes with a visibility of about 96 %. Furthermore, by measuring the correlation function g(2)(τ) at the exits of the interferometer, the single-photon character of the interfering light is demonstrated. However, it is impossible to observe both photon path and interference fringes with the same experimental configuration. In this way, our experiment clearly illustrates the wave-particle duality of light.