Wang Xiang-bin

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To transmit an unknown qubit robustly through the noisy channel, one may first encode it into a certain quantum error correction code and then transmit it. The remote party decodes it and stores it. Sending a qubit in such a way can significantly reduces the error rate compared with directly sending the qubit itself. Here we show how to realize such a(More)
A conditional geometric phase shift gate, which is fault tolerant to certain types of errors due to its geometric nature, was realized recently via nuclear magnetic resonance (NMR) under adiabatic conditions. However, in quantum computation, everything must be completed within the decoherence time. The adiabatic condition makes any fast conditional Berry(More)
It is conjectured that the an entanglement output states from a beam splitter requires the non-classicality in the input state(M. Here we give a proof for this conjecture. The beam splitter is one of the few quantum devices that may act as the entangler. The entangler properties of a beam splitter have been studied in the past [1–4]. In particular, Kim et(More)
Two remote parties, Alice and Bob initially share some non-maximally entangled states. Through the entanglement concentration by local operation and classical communication(LOCC), they may obtain an outcome of maximally entangled states in the price of decreasing the number of pairs shared by them. Recently, entanglement concentration was experimently(More)
We propose a scheme to produce the maximally two photon polarization entangled state(EPR state) with single photon sources and the passive linear optics devices. In particular, our scheme only requires the normal photon detectors which distinguish the vacuum and non-vacuum Fock number states. A sophisticated photon detector distinguishing one-photon state(More)
Motivated for the fault tolerant quantum computation, a quantum gate by adi-abatic geometric phase shift is extensively investigated recently. Due to the enviromental noise, the decoherence time for a quantum state can be very short. In the adiabatic quantum computation, if we change the Hamiltonian slowly, the decoherence error is increased, if we change(More)
Two remote parties, Alice and Bob initially share some non-maximally entangled states. Through the entanglement concentration by local operation and classical communication(LOCC), they may obtain an outcome of maximally entangled states in the price of decreasing the number of pairs shared by them. Recently, entanglement concentrations have been(More)
We propose a scheme to produce the maximally two photon polarization entangled state (EPR state) with single photon sources and the passive linear optics devices. In particular, our scheme only requires the normal photon detectors which distinguish the vacuum and non-vacuum Fock number states. A sophisticated photon detector distinguishing one-photon state(More)
We give a simple way to detersministically rule out the event that two pairs of photons are generated in the same side of the nolinear crystal in the type II parametric downconversion. By this new scheme, everytime when the concin-dence is observed it is indeed an event that one pair of photons is generated in each side of the crystal therefore the(More)