Fully autocompensating high-dimensional quantum cryptography by optical phase conjugation

TL;DR

This paper introduces a bidirectional quantum communication system utilizing optical phase conjugation to achieve fully autocompensating high-dimensional quantum cryptography, enhancing security and robustness against perturbations.

Contribution

It demonstrates a novel autocompensating high-dimensional QKD protocol based on optical phase conjugation, capable of counteracting phase shifts and mode couplings.

Findings

Autocompensation of phase shifts and mode couplings after a single round trip.

Implementation of high-dimensional QKD protocols with enhanced security.

Feasibility of using single photons or coherent states for secure quantum communication.

Abstract

We present a bidirectional quantum communication system based on optical phase conjugation for achieving fully autocompensating high-dimensional quantum cryptography. We prove that random phase shifts and couplings among 2N spatial and polarization optical modes described by SU(2N) transformations due to perturbations are autocompensated after a single round trip between Alice and Bob. Bob can use a source of single photons or, alternatively, coherent states and then Alice attenuates them up to a single photon level, and thus non-perturbated 1-qudit states are generated for high-dimensional QKD protocols, as the BB84 one, of a higher security.