Efficient quantum repeater in perspectives of both entanglement concentration rate and LOCC complexity

TL;DR

This paper proposes an efficient quantum repeater protocol that optimizes entanglement concentration rate and reduces LOCC complexity, enhancing long-distance quantum entanglement distribution.

Contribution

It introduces a new protocol for quantum repeaters that achieves optimal entanglement concentration with lower local operation and classical communication complexity.

Findings

Achieved optimal entanglement concentration rate with minimal LOCC.

Derived criteria for projective measurements to maximize success probability.

Established an upper bound on success probability for general pure states.

Abstract

Quantum entanglement is an indispensable resource for many significant quantum information processing tasks. However, because of the noise in quantum channels, it is difficult to distribute quantum entanglement over a long distance in practice. A solution for this challenge is the quantum repeater which can extend the distance of entanglement distribution. In this scheme, the time consumption of classical communication and local operations takes an important place in perspective of time efficiency. Motivated by this observation, we exploit the basic quantum repeater scheme in perspectives of not only the optimal rate of entanglement concentration but also the complexity of local operations and classical communication. Firstly, we consider the case where two two-qubit pure states are prepared. We construct a protocol with the optimal entanglement concentration rate and less consumption of local operations and classical communication. We also find a criteria for the projective measurements to achieve the optimal probability. Secondly, we exploit the case where two general pure states are prepared and general measurements are considered. We get an upper bound on the probability for a successful measurement operation to produce a maximally entangled state without any further local operations.