Optimal enhancement of the fidelity of two qubits

Preprint
Publisher Website
Google Scholar
  • 17 March 2002
Abstract
We consider a single copy of a mixed state of two qubits and prove tight lower and upper bounds for its fidelity (the maximum singlet fraction) in terms of its concurrence or negativity. Next we explicitly derive the optimal filtering operations and the optimal trace-preserving local operations assisted by classical communication (LOCC) such as to maximize the fidelity of a given copy of a mixed state of two qubits. The optimal LOCC operations turn out to be very simple and implementable by 1-LOCC protocols, and always yield a fidelity larger then 1/2 if the original state was entangled. We discuss the results in the light of optimal distillation protocols and show that the maximal achievable fidelity gives the exact expression for the optimal teleportation fidelity that can be achieved with a mixed state.

This publication has 0 references indexed in Scilit: