Distilling Entanglement from Fermions

Entanglement purification of unknown quantum states

A concern has been expressed that “the Jaynes principle can produce fake entanglement” [R. Horodecki et al., Phys. Rev. A 59, 1799 (1999)]. In this paper we discuss the general problem of distilling maximally entangled states from N copies of a bipartite quantum system about which only partial information is known, for instance in the form of a given expectation value. We point out that there i...

The entanglement of damped noon-state and its performance in phase measurement

The state evolution of the initial optical noon state is investigated. The residue entanglement of the state is calculated after it is damped by amplitude and phase damping. The relative entropy of entanglement of the damped state is exactly obtained. The performance of direct application of the damped noon state is compared with that of firstly distilling the docoherence damped state then appl...

Distilling entanglement from random cascades with partial “ Which Path ” ambiguity

We develop a framework to calculate the density matrix of a pair of photons emitted in a decay cascade with partial " which path " ambiguity. We describe an appropriate entanglement distillation scheme which works also for certain random cascades. The qualitative features of the distilled entanglement are presented in a two dimensional " phase diagram ". The theory is applied to the quantum tom...

How to Exploit Local Information When Distilling Entanglement

Distillation protocols enable generation of high quality entanglement even in the presence of noise. Existing protocols ignore the presence of local information in mixed states produced from some noise sources such as photon loss, amplitude damping or thermalization. We propose new protocols that exploit local information in mixed states. Our protocols converge to higher fidelities in fewer rou...

Entanglement entropy of compressible holographic matter: Loop corrections from bulk fermions