Optimal multipartite entanglement concentration of electron-spin states based on charge detection and projection measurements

Abstract

We propose an optimal entanglement concentration protocol (ECP) for nonlocal N-electron systems in a partially entangled pure state, resorting to charge detection and the projection measurement on an additional electron. For each nonlocal N-electron system, one party in quantum communication, say Alice first entangles it with an additional electron, and then she projects the additional electron into an orthogonal basis for dividing the N-electron systems into two groups. In the first group, the N parties obtain a subset of N-electron systems in a maximally entangled state directly. In the second group, they obtain some less-entangled N-electron systems which are the resource for the entanglement concentration in the next round. By iterating the entanglement concentration process several times, the present ECP has the maximal success probability, the theoretical limit of an ECP as it just equals to the entanglement of the partially entangled state, far higher than others, without resorting to a collective unitary evolution.

Maximal entanglement concentration for a set of $$(n+1)$$ ( n + 1 ) -qubit states

“…have been proposed. Nevertheless, apart from using different methods for designing ECPs, the possibility of implementation of ECPs is also studied for different technologies, like linear optics [12,13,14,15,16], quantum dot and microcavity systems [17,18,19,20] and electronic technologies [21,22]. Yamamoto et al [14] experimentally realized ECP from two copies of the state |Φ = α|00 + β|11 , where |α| 2 + |β| 2 = 1 using polarising beam splitters (PBSs), wave plates and photon detectors.…”

Direct measurement of the concurrence for two-qubit electron spin entangled pure state based on charge detection

“…That is to say, if one measures the charge degree of freedom with the charge detector, [47] the spin degree of freedom will not be affected. Subsequently, many quantum information processing protocols were proposed, such as entanglement purification, [48][49][50] entanglement concentration, [51][52][53][54][55][56][57] the generation of the cluster states, [58,59] hyperentanglement Bell-state analysis, [60,61] and the measurement-based quantum computation scheme from spin systems to fermion systems. [62] As the entanglement encoded in conduction electron plays an important role in current quantum information processing, in this paper, we will describe an alternative approach to measure the concurrence of the entanglement.…”

Hyperconcentration for entanglement in two degrees of freedom

“…Sheng et al proposed another efficient entanglement concentration scheme, assisted by a single photon state in 2012 [30]. There have also been some entanglement concentration schemes treating other systems besides photons [17,18,[31][32][33][34][35][36], and, more recently, entanglement concentration schemes for W state [37][38][39][40][41][42][43][44][45].…”