Generation and distribution of high-dimensional frequency-entangled qudits

TL;DR

This paper presents a new method to generate and distribute high-dimensional frequency-entangled qudits over 15 km of optical fiber, advancing quantum communication capabilities.

Contribution

It introduces a novel scheme combining spectral engineering and spectrally resolved interference to produce and distribute high-dimensional entangled qudits.

Findings

Successfully generated frequency-entangled qudits with dimension >10

Distributed entangled qudits over 15 km of optical fiber

Characterized spectral correlation structures of the qudits

Abstract

We demonstrate a novel scheme to generate frequency-entangled qudits with dimension number higher than 10 and to distribute them over optical fibers of 15 km in total length. This scheme combines the technique of spectral engineering of biphotons generated by spontaneous parametric down-conversion and the technique of spectrally resolved Hong-Ou-Mandel interference. We characterized the comb-like spectral correlation structures of the qudits by time of arrival measurement and correlated spectral intensity measurement. The generation and distribution of the distinct entangled frequency modes may be useful for quantum cryptography, quantum metrology, quantum remote synchronization, as well as fundamental test of stronger violation of local realism.