报告题目：窄线宽纠缠光子对的产生及应用

报告时间：9月26日 上午 9：30

报告地点：理六栋 405室

摘要：As a standard method for producing correlated photon pairs (biphotons), spontaneous parametric down-conversion in nonlinear crystal usually has a wide bandwidth (terahertz) and very short coherence time (pico-seconds). Within spontaneous four-wave mixing process in cold atom ensembles, here we present a method for producing narrow-band (megahertz) Stokes and anti-Stokes paired photons. As detecting a Stokes photon heralds the generation of its paired anti-Stokes photon, the biphoton source is also used as a good heralded single photon source. With narrow-band frequency-tunable entangled biphotons, we observe coalescence interference for both degenerate and nondegenerate photons, and find that the path-exchange symmetry plays a more important role in the Hong-Ou-Mandel interference than the temporal or frequency indistinguishability. Based on a direct modulation of heralded single-photon waveform with an arbitrary phase pattern, we demonstrate the first proof of principle differential phase shift quantum key distribution experiment using heralded single photons. When the single-photon waveform is modulated to exponential growth, we experimentally demonstrate that a single photon can be almost completely loaded into a Fabry-Perot cavity, which has a potential application in cavity Quantum Electrodynamics field.

参考文献：

Chang Liu, Yuan Sun, Luwei Zhao, Shanchao Zhang, M. M. T. Loy, and Shengwang Du, "Efficiently loading a single photon into a single-sided Fabry-Perot cavity," Phys. Rev. Lett. (accepted, 2014).

Chang Liu, Shanchao Zhang, Luwei Zhao, Peng Chen, C. -H. F. Fung, H. F. Chau, M. M. T. Loy, and Shengwang Du, "Differential-phase-shift quantum key distribution using heralded narrow-band single photons," Opt. Express 21, 9505 (2013).

Chang Liu, J. F. Chen, Shanchao Zhang, Shuyu Zhou, Yoon-Ho Kim, M. M. T. Loy, G. K. L. Wong, and Shengwang Du, "Two-photon interferences with degenerate and nondegenerate paired photons," Phys. Rev. A 85, 021803(R) (2012).