The detection of a particle in electromagnetic plus gravitational fields is investigated. We obtain a set of quantum nondemolition variables. The continuous measurements of these nondemolition parameters are analyzed ...The detection of a particle in electromagnetic plus gravitational fields is investigated. We obtain a set of quantum nondemolition variables. The continuous measurements of these nondemolition parameters are analyzed in the framework of restricted path integral formalism. We manipulate the corresponding propagators, and deduce the probabilities associated with the possible measurement outputs.展开更多
We present a universal way to concentrate an arbitrary N-particle less-entangled W state into a maximally entangled W state with different parity check gates.It comprises two protocols.The first protocol is based on t...We present a universal way to concentrate an arbitrary N-particle less-entangled W state into a maximally entangled W state with different parity check gates.It comprises two protocols.The first protocol is based on the linear optical elements,say the partial parity check gate and the second protocol uses the quantum nondemolition measurement to construct the complete parity check gate.Both protocols can achieve the concentration task.These protocols have several advantages.First,they can obtain a maximally entangled W state only with the help of some single photons,which greatly reduces the number of entanglement resources.Second,in the first protocol,only linear optical elements are required,which is feasible with current techniques.Third,the second protocol can be repeated to perform the concentration step and obtain a higher success probability.All these advantages make it quite useful in current quantum communication and computation applications.展开更多
In this paper, we propose a very simple scheme to probe the quantum and classical correlation including quantum entanglement of Bell diagonal state. In the probing process, the correlation of Bell diagonal state, even...In this paper, we propose a very simple scheme to probe the quantum and classical correlation including quantum entanglement of Bell diagonal state. In the probing process, the correlation of Bell diagonal state, even the state itself, is not disturbed, which means a non-destructive probing. In addition, our scheme can be performed even though the two qubits of the Bell diagonal state are separate in space.展开更多
文摘The detection of a particle in electromagnetic plus gravitational fields is investigated. We obtain a set of quantum nondemolition variables. The continuous measurements of these nondemolition parameters are analyzed in the framework of restricted path integral formalism. We manipulate the corresponding propagators, and deduce the probabilities associated with the possible measurement outputs.
基金supported by the National Natural Science Foundation of China(Grant Nos.11474168and 61401222)the Qing Lan Project in Jiangsu Province+2 种基金Specialized Research Fund for the Doctoral Program of Higher Education(Grant No20113223120002)University Natural Science Research Project of Jiangsu Province(Grant No.11KJB510016)the Priority Academic Development Program of Jiangsu Higher Education Institutions,China
文摘We present a universal way to concentrate an arbitrary N-particle less-entangled W state into a maximally entangled W state with different parity check gates.It comprises two protocols.The first protocol is based on the linear optical elements,say the partial parity check gate and the second protocol uses the quantum nondemolition measurement to construct the complete parity check gate.Both protocols can achieve the concentration task.These protocols have several advantages.First,they can obtain a maximally entangled W state only with the help of some single photons,which greatly reduces the number of entanglement resources.Second,in the first protocol,only linear optical elements are required,which is feasible with current techniques.Third,the second protocol can be repeated to perform the concentration step and obtain a higher success probability.All these advantages make it quite useful in current quantum communication and computation applications.
基金Supported by the National Natural Science Foundation of China under Grant No. 11175033the Fundamental Research Funds of the Central Universities under Grant No. DUT12LK42
文摘In this paper, we propose a very simple scheme to probe the quantum and classical correlation including quantum entanglement of Bell diagonal state. In the probing process, the correlation of Bell diagonal state, even the state itself, is not disturbed, which means a non-destructive probing. In addition, our scheme can be performed even though the two qubits of the Bell diagonal state are separate in space.
