An error-free protocol for quantum entanglement distribution in long distance quantum communication.
ABSTRACT Quantum entanglement distribution is an essential part of quantum communication and computation protocols. Here, linear optic elements are employed for distribution of quantum entanglement over long distance. Polarization beam splitters and wave plates are used for realization of an error-free protocol for broadcasting quantum entanglement in optical quantum communication. This protocol can determine maximum distance of quantum communication to transmit quantum information without decoherence. Error detection and error correction are performed in the proposed scheme. In other words, if bit-flip occurs along the quantum channel, the end stations (Alice and Bob) can detect this state changing and obtain the correct state (entangled photon) on the another port. Existing general error detection protocols are based on the quantum controlled-NOT (CNOT) or similar quantum logic operations, which are very difficult to implement experimentally. Here we present a feasible scheme for the implementation of entanglement distribution based on linear optics element that does not need quantum CNOT gate.
Conference Proceeding: Quantum Cryptography[show abstract] [hide abstract]
ABSTRACT: In this paper, the elementary aspects of quantum cryptography are presented. First, we start with the introduction and history of quantum cryptography. Second, we give the definition of classical and quantum cryptography and emphasize the difference between the two. The idea of quantum cryptography will be explained further in the subsequent section, where the famous quantum key distribution example is presented. Lastly, we give the results of some computer simulations.Signal Processing and Communications Applications, 2007. SIU 2007. IEEE 15th; 07/2007
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ABSTRACT: We present a way for entanglement purification based on two parametric down-conversion (PDC) sources with cross-Kerr nonlinearities. It is comprised of two processes. The first one is a primary entanglement purification protocol for PDC sources with nondestructive quantum nondemolition (QND) detectors by transferring the spatial entanglement of photon pairs to their polarization. In this time, the QND detectors act as the role of controlled-not (CNot) gates. Also they can distinguish the photon number of the spatial modes, which provides a good way for the next process to purify the entanglement of the photon pairs kept more. In the second process for entanglement purification, new QND detectors are designed to act as the role of CNot gates. This protocol has the advantage of high yield and it requires neither CNot gates based on linear optical elements nor sophisticated single-photon detectors, which makes it more convenient in practical applications. Comment: 8 pages, 7 figuresPhysical Review A 04/2008; · 3.04 Impact Factor
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ABSTRACT: Using polarization-entangled photons from spontaneous parametric down-conversion, we have implemented Ekert's quantum cryptography protocol. The near-perfect correlations of the photons allow the sharing of a secret key between two parties. The presence of an eavesdropper is continually checked by measuring Bell's inequalities. We investigated several possible eavesdropper strategies, including pseudo-quantum-nondemolition measurements. In all cases, the eavesdropper's presence was readily apparent. We discuss a procedure to increase her detectability.Physical Review Letters 06/2000; 84(20):4733-6. · 7.94 Impact Factor