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Q: Fachverband Quantenoptik und Photonik

Q 47: Quanteninformation (Quantenkommunikation)

Q 47.1: Talk

Wednesday, March 21, 2007, 16:30–16:45, 5L

Towards the Solution of NP Problem: Indistinguished controllable single photons from independent atomic ensembles — •Yu-Ao Chen¹, Shuai Chen¹, Markus Koch¹, Thorsten Straßel¹, Zhen-Sheng Yuan¹, Jörg Schmiedmayer², and Jian-Wei Pan¹ — ¹Physikalisches Institut, Universität Heidelberg, Philosophenweg 12, D-69120 Heidelberg, Germany — ²Atominstitut der Österreichischen Universitäten, TU-Wien, A-1020 Vienna, Austria

Quantum repeater hold the promise for revolutionary advances to solve the NP problem from the losses and decoherence in the communication channel by a distribution of quantum resources over remote locations and quantum memory.

We use collective spin excitation of atoms as a media for quantum memory. Here we present an implementation of feed forward control of two atomic memories. We use independent "write" laser sources to map the quantum states to the collective spin excitation and again we use independent "read" lasers to retrieve the quantum states from the two atomic memories respectively. We will show that, by using a feed forward circuit, the probability of simultaneously obtaining a pair of single photons will be increased by orders of magnitude. As an application, we show the indistinguishability of independently generated single photons by the observation of destructive interference of their wave packets. Our results demonstrate experimentally a basic principle for enabling scalable quantum communication networks and linear optical quantum computation.