We demonstrate nonlocal modulation of entangled photons with truly distributed RF clocks. Leveraging a custom radio-over-fiber (RFoF) system characterized via classical spectral interference, we validate its effectiveness for quantum networking by multiplexing the RFoF clock with one photon from a frequency-bin-entangled pair and distributing the coexisting quantum-classical signals over fiber. Phase modulation of the two photons reveals nonlocal correlations in excellent agreement with theory: in-phase modulation produces additional sidebands in the joint spectral intensity, while out-of-phase modulation is nonlocally canceled. Our simple, feedback-free design attains sub-picosecond synchronization -- namely, drift less than ∼0.5 ps in a 5.5 km fiber over 30 min (fractionally only ∼2×10−8 of the total fiber delay) -- and should facilitate frequency-encoded quantum networking protocols such as high-dimensional quantum key distribution and entanglement swapping, unlocking frequency-bin qubits for practical quantum communications in deployed metropolitan-scale networks.
@article{arxiv.2407.17330,
title = {Quantum nonlocal modulation cancellation with distributed clocks},
author = {Stephen D. Chapman and Suparna Seshadri and Joseph M. Lukens and Nicholas A. Peters and Jason D. McKinney and Andrew M. Weiner and Hsuan-Hao Lu},
journal= {arXiv preprint arXiv:2407.17330},
year = {2025}
}