Efficient two-step entanglement concentration for arbitraryWstates

Abstract

We present two two-step practical entanglement concentration protocols (ECPs) for concentrating an arbitrary three-particle less-entangled W state into a maximally entangled W state assisted with single photons. The first protocol uses the linear optics and the second protocol adopts the cross-Kerr nonlinearity to perform the protocol. In the first protocol, based on the post-selection principle, three parties say Alice, Bob and Charlie in different distant locations can obtain the maximally entangled W state from the arbitrary less-entangled W state with a certain success probability. In the second protocol, it dose not require the parties to posses the sophisticated single-photon detectors and the concentrated photon pair can be retained after performing this protocol successfully. Moreover, the second protocol can be repeated to get a higher success probability. Both protocols may be useful in practical quantum information applications.

Efficient Concentration Protocols for the Single-Photon Entanglement State with Polarization Feature

“…As the phase shift can be measured by the homodyne measurement, the photon number in each spatial mode can be detected without destroying the photons. The crossKerr nonlinearity provides a good way to construct the QND, which has played an important role in the quantum information field, such as quantum logic gate [77,78], quantum teleportation [79], entanglement purification and concentration [43][44][45][46][47], and so on [80][81][82][83][84][85][86][87][88][89][90][91].…”

“…In 2010, the first ECP for SPE was proposed by Sheng et al In the ECP, we can distill one pair of maximally entangled single-photon state from two pairs of less-entangled single-photon states [44]. Later, Sheng proposed two efficient single-photon assisted ECPs for arbitrary less-entangled twophoton entanglement state and W state, respectively [45,46]. In 2013 and 2014, inspired by the above single-photon assisted ECPs, we proposed the improved ECPs for arbitrary lessentangled SPE and single-photon multi-mode W state [47,48].…”

Quantum Entanglement Concentration Based on Nonlinear Optics for Quantum Communications

“…There is a phase difference between them, and one can perform a phase-flipping operation with the help of the wave plate to convert Equation (60) to Equation (59).…”

Two-step measurement of the concurrence for hyperentangled state

“…It can be used to perform the quantum nondemolition (QND) measurement, which has been widely used in quantum information processing, such as construction of the CNOT gate [39,40], performing the Bell-state analysis [28,41], entanglement purification and concentration [42][43][44][45], and so on [46][47][48][49][50][51][52]. The Hamiltonian of a cross-Kerr nonlinear interaction is H =hχa † s a s a † p a p [39].…”