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arXiv:1401.2526

Detection of the nonlocal atomic entanglement assisted with single photons

Yu‐Bo Sheng, Lan Zhou

Published Jan 11, 2014• 0 citations
arXivHTMLPDF

Abstract

We present an efficient way for measuring the entanglement of the atoms. Through the auxiliary single photons input-output process in cavity quantum electrodynamics (QED), the concurrence of the atomic entanglement can be obtained according to the success probability of picking up the singlet states of the atoms. This protocol has three advantages: First, we do not require the sophisticated controlled-not (CNOT) gates. Second, the distributed atoms are not required to intact with each other. Third, the atomic entanglement can be distributed nonlocally, which provides its important applications in distributed quantum computation.

DOI
10.48550/arxiv.1401.2526

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Abstract An experimental scheme for the measurement of entanglement between two two‐level atoms is proposed. This scheme requires one of the two entangled atoms to interact with a cavity field dispersively, and it is shown that by measuring the zero time‐delay second‐order coherence function of the cavity field, one can measure the concurrence of an arbitrary Bell‐like atomic two‐qubit state. As this scheme requires only one of the atoms to interact with the measured cavity, the entanglement quantification becomes independent of the location of the other atom. Therefore, this scheme can have important implications for entanglement quantification in distributed quantum systems.
We propose an efficient protocol for measuring the concurrence of arbitrary two-photon pure entangled state with the help of the photonic Faraday rotation. In the protocol, the concurrence of the photonic entangled state can be conversed into the total success probability for picking up the odd-parity photonic state. For completing the measurement task, we require some auxiliary three-level atoms, which are trapped in the low-quality cavities. Our protocol can be well realized under current experimental conditions. Moreover, under practical imperfect atom state detection and photonic Faraday rotation conditions, our protocol can also work well. Based on these features, our protocol may be useful in current quantum information processing.