High-dimensional time-frequency entanglement in a singly-filtered biphoton frequency comb

TL;DR

This paper demonstrates a high-dimensional biphoton frequency comb with singly-filtered entanglement, verified through interference and correlation measurements, and successfully distributed over a 10 km fiber link, advancing quantum information processing and networking.

Contribution

It introduces a novel singly-filtered high-dimensional biphoton frequency comb generated via spectral shaping, with verified high-dimensional entanglement and distribution over long-distance fiber.

Findings

High-dimensional energy-time entanglement verified through Franson interference.

Successful distribution of entangled states over 10 km fiber link.

Quantification of frequency and temporal entanglement using Schmidt mode decomposition.

Abstract

High-dimensional quantum entanglement is a cornerstone for advanced technology enabling large-scale noise-tolerant quantum systems, fault-tolerant quantum computing, and distributed quantum networks. The recently developed biphoton frequency comb (BFC) provides a powerful platform for high-dimensional quantum information processing in its spectral and temporal quantum modes. Here we propose and generate a singly-filtered high-dimensional BFC via spontaneous parametric down-conversion by spectrally shaping only the signal photons with a Fabry-Perot cavity. High-dimensional energy-time entanglement is verified through Franson-interference recurrences and temporal correlation with low-jitter detectors. Frequency- and temporal- entanglement of our singly-filtered BFC is then quantified by Schmidt mode decomposition. Subsequently, we distribute the high-dimensional singly-filtered BFC state over a 10 km fiber link with a post-distribution time-bin dimension lower bounded to be at least 168. Our demonstrations of high-dimensional entanglement and entanglement distribution show the capability of the singly-filtered quantum frequency comb for high-efficiency quantum information processing and high-capacity quantum networks.