J. R. Schaibley, A. P. Burgers, G. A. McCracken, L-M Duan, P. R. Berman, D. G. Steel, A. S. Bracker, D. Gammon, L. J. Sham
The electron spin state of a singly charged semiconductor quantum dot has been shown to form a suitable single qubit for quantum computing architectures with fast gate times. A key challenge in realizing a useful quantum dot quantum computing architecture lies in demonstrating the ability to scale the system to many qubits. In this letter, we report an all optical experimental demonstration of quantum entanglement between a single electron spin confined to single charged semiconductor quantum dot and the polarization state of a photon spontaneously emitted from the quantum dot's excited state. After correcting for erroneous correlations, we obtain a lower bound on the fidelity of entanglement of 0.59, limited primarily by the timing resolution of available single photon detectors. The inferred (usable) entanglement generation rate is 3 x 10^3 1/s. This spin-photon entanglement is the first step to a scalable quantum dot quantum computing architecture relying on photon (flying) qubits to mediate entanglement between distant nodes of a quantum dot network.
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http://arxiv.org/abs/1210.5555
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