Quantum cloning a pair of orthogonally polarized photons with linear optics

TL;DR

This paper presents a linear optical probabilistic scheme for optimal cloning of orthogonally polarized photon pairs, avoiding nonlinear media, and also adaptable for implementing a two-qubit partial SWAP gate for quantum computing.

Contribution

It introduces a novel linear optical setup for quantum cloning of photon pairs and extends its application to quantum gate implementation, enhancing linear optics quantum information processing.

Findings

Achieves optimal cloning without nonlinear media

Utilizes a modified unbalanced Mach-Zehnder interferometer

Enables implementation of a two-qubit partial SWAP gate

Abstract

A linear optical probabilistic scheme for the optimal cloning of a pair of orthogonally-polarized photons is devised, based on single- and two-photon interferences. It consists in a partial symmetrization device, realized with a modified unbalanced Mach-Zehnder interferometer, followed by two independent Hong-Ou-Mandel interferometers. This scheme has the advantage that it enables quantum cloning without the need for stimulated amplification in a nonlinear medium. It can also be modified so to make an optical two-qubit partial SWAP gate, thereby providing a potentially useful tool to linear optics quantum computing.