Multipartite entanglement purification with quantum nondemolition detectors

TL;DR

This paper proposes a multipartite entanglement purification scheme using quantum nondemolition detectors based on cross-Kerr nonlinearities, avoiding the need for controlled-not gates and enabling more practical quantum communication.

Contribution

It introduces a novel purification method that replaces CNOT gates with QNDs, improving efficiency and feasibility for multipartite entangled states.

Findings

Scheme effectively corrects bit-flipping errors

Scheme effectively corrects phase-flipping errors

Does not require sophisticated single-photon detectors

Abstract

We present a scheme for multipartite entanglement purification of quantum systems in a Greenberger-Horne-Zeilinger state with quantum nondemolition detectors (QNDs). This scheme does not require the controlled-not gates which cannot be implemented perfectly with linear optical elements at present, but QNDs based on cross-Kerr nonlinearities. It works with two steps, i.e., the bit-flipping error correction and the phase-flipping error correction. These two steps can be iterated perfectly with parity checks and simple single-photon measurements. This scheme does not require the parties to possess sophisticated single photon detectors. These features maybe make this scheme more efficient and feasible than others in practical applications.