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Updated: Jun 18, 2025

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Single-Photon Interference over 8.4 km Urban Atmosphere: Toward Testing Quantum Effects in Curved Spacetime with
Hui-Nan Wu1, Yu-Huai Li1, Bo Li1
1<a href="https://ror.org/01jeedh73">Hefei National Research Center for Physical Sciences at the Microscale</a> and School of Physical Sciences, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, 230026, Hefei, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, 201315, Shanghai, China and Hefei National Laboratory, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, 230088, Hefei, China.
Abstract:
The emergence of quantum mechanics and general relativity has transformed our understanding of the natural world significantly. However, integrating these two theories presents immense challenges, and their interplay remains untested. Recent theoretical studies suggest that the single-photon interference covering huge space can effectively probe the interface between quantum mechanics and general relativity. We developed an alternative design using unbalanced Michelson interferometers to address this and validated its feasibility over an 8.4 km free-space channel. Using a high-brightness single-photon source based on quantum dots, we demonstrated single-photon interference along this long-distance baseline. We achieved a phase measurement precision of 16.2 mrad, which satisfied the measurement requirements for a gravitational redshift at the geosynchronous orbit by 5 times the standard deviation. Our results confirm the feasibility of the single-photon version of the Colella-Overhauser-Werner experiment for testing the quantum effects in curved spacetime.
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