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Q: Fachverband Quantenoptik und Photonik

Q 35: Poster Quantenkommunikation

Q 35.2: Poster

Tuesday, March 20, 2007, 16:30–18:30, Poster C

Simultaneous retrieval of single photons from two atomic ensembles — •Markus Koch¹, Shuai Chen¹, Yu-Ao Chen¹, Thorsten Strassel¹, Zhen-Sheng Yuan¹, Bo Zhao¹, Jörg Schmiedmayer², and Jian-Wei Pan¹ — ¹Physikalisches Institut , Universität Heidelberg, Philosophenweg 12, Germany — ²Atominstitut österreichischer Universitäten, TU Wien, Stadionallee 2, 1020 Wien, Austria

Duan, Lukin, Cirac and Zoller have proposed a scheme for long distance quantum communication based on atomic ensembles and linear optical elements [Duan et al., Nature 414, 413, 2001].
Here we demonstrate that one single cloud of atoms can serve as two independent ensembles. A cloud of cold ⁸⁷Rb atoms was prepared in a magneto optical trap. Two independent, non overlapping write beams were used to create collective excitations in two spatially seperated regions of the cloud. The excitations can be read out independently. A violation of the Cauchy-Schwartz inequality proves the non classical character of the photons from each ensemble. Using a feed forward circuit we can simultaneously recover single photons from each ensemble and we will demonstrate their indistinguishability for different degrees of freedom by their interference on a beam splitter. Our next goal is to extend the storage time in order to demonstrate entanglement of two atomic ensembles as it is required for the DLCZ protocol.