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arXiv:1401.6719

Measurement of arbitrary two-photon entanglement state with the photonic Faraday rotation

Lan Zhou

Published Jan 27, 2014• 2 citations
arXivHTMLPDF

Abstract

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.

DOI
10.48550/arxiv.1401.6719

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By utilizing Faraday rotation of photons, we present a highly efficient protocol for entanglement concentration of atomic Bell states, which departs from the conventional method of sequential interactions between the auxiliary photon and two optical cavities. Instead, the simultaneous interaction of the auxiliary photon with two atomic cavities is involved in order to significantly reduce the time requirement for achieving atomic Bell state entanglement concentration. By employing iterative applications of the protocol for entanglement concentration, the discarded states can be repeatedly concentrated, efficiently increasing the probability of success. Furthermore, our entanglement concentration protocols (ECPs) operate in low-Q cavities, which are easier to implement in practical applications than high-Q cavities. Finally, it can be generalized to an N -atom GHZ states entanglement concentration protocol.
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We propose a protocol for directly measuring the concurrence of a two-qubit electronic pure entangled state. To complete this task, we first design a parity-check measurement (PCM) which is constructed by two polarization beam splitters (PBSs) and a charge detector. By using the PCM for three rounds, we can achieve the concurrence by calculating the total probability of picking up the odd parity states from the initial states. Since the conduction electron may be a good candidate for the realization of quantum computation, this protocol may be useful in future solid quantum computation.