A quantum repeater based on decoherence free subspaces

TL;DR

This paper evaluates a quantum repeater utilizing decoherence free subspaces, demonstrating it can outperform traditional repeaters affected by decoherence, thus enabling more reliable long-distance quantum communication.

Contribution

It analyzes the impact of decoherence on a decoherence free quantum repeater and compares its performance to conventional repeaters, showing significant improvements under certain conditions.

Findings

Decoherence free quantum repeater outperforms traditional repeaters with long waiting times.

Decoherence effects on entanglement swapping and purification are quantitatively analyzed.

The scheme offers a promising approach for long-distance quantum communication.

Abstract

We study a quantum repeater which is based on decoherence free quantum gates recently proposed by Klein et al. [Phys. Rev. A 73, 012332 (2006)]. A number of operations on the decoherence free subspace in this scheme makes use of an ancilla qubit, which undergoes dephasing and thus introduces decoherence to the system. We examine how this decoherence affects entanglement swapping and purification as well as the performance of a quantum repeater. We compare the decoherence free quantum repeater with a quantum repeater based on qubits that are subject to decoherence and show that it outperforms the latter when decoherence due to long waiting times of conventional qubits becomes significant. Thus, a quantum repeater based on decoherence free subspaces is a possibility to greatly improve quantum communication over long or even intercontinental distances.