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

• Published in: Communications physics 2023-09, Vol.6 (1), p.278-12, Article 278
• Main Authors: Cheng, Xiang, Chang, Kai-Chi, Sarihan, Murat Can, Mueller, Andrew, Spiropulu, Maria, Shaw, Matthew D., Korzh, Boris, Faraon, Andrei, Wong, Franco N. C., Shapiro, Jeffrey H., Wong, Chee Wei
• Format: Article
• Language: English
• Subjects: 639/766/400/3925; 639/766/483; Bins; Data processing; Electrons; Entangled states; Fabry-Perot interferometers; Fault tolerance; Information processing; Physics; Physics and Astronomy; Quantum computing; Quantum cryptography; Quantum entanglement; Quantum phenomena
• ISSN: 2399-3650; 2399-3650
• DOI: 10.1038/s42005-023-01370-2

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-Pérot 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 singly-filtered quantum frequency comb’s capability for high-efficiency quantum information processing and high-capacity quantum networks. High-dimensional quantum entanglement is generated via a singly filtered biphoton frequency comb, with energy-time entanglement witnessed for both between time bins and frequency bins. Entanglement distribution of such high dimensional entangled state is verified with high quality and provides a testbed for high-dimensional quantum key distribution.