Harnessing high-dimensional hyperentanglement through a biphoton frequency comb

TL;DR

This paper demonstrates the first simultaneous high-dimensional hyperentanglement in energy and time domains using a biphoton frequency comb, showcasing quantum revivals and Bell inequality violations for advanced quantum communication.

Contribution

It introduces a novel biphoton frequency comb platform enabling high-dimensional hyperentanglement in energy-time, surpassing previous limitations and enhancing quantum communication capabilities.

Findings

Observed Hong-Ou-Mandel quantum revival with 19 time-bins and 96.5% visibility.

Witnessed high-dimensional energy-time entanglement through Franson revivals with 97.8% visibility.

Violated Bell inequalities with up to 10.95 deviations and S-parameters up to 2.76.

Abstract

Quantum entanglement is a fundamental resource for secure information processing and communications, where hyperentanglement or high-dimensional entanglement has been separately proposed towards high data capacity and error resilience. The continuous-variable nature of the energy-time entanglement makes it an ideal candidate for efficient high-dimensional coding with minimal limitations. Here we demonstrate the first simultaneous high-dimensional hyperentanglement using a biphoton frequency comb to harness the full potential in both energy and time domain. The long-postulated Hong-Ou-Mandel quantum revival is exhibited, with up to 19 time-bins, 96.5% visibilities. We further witness the high-dimensional energy-time entanglement through Franson revivals, which is observed periodically at integer time-bins, with 97.8% visibility. This qudit state is observed to simultaneously violate the generalized Bell inequality by up to 10.95 deviations while observing recurrent Clauser-Horne-Shimony-Holt S-parameters up to 2.76. Our biphoton frequency comb provides a platform in photon-efficient quantum communications towards the ultimate channel capacity through energy-time-polarization high-dimensional encoding.