Enabling phase stabilization of quantum networks via displacement-enhanced photon counting

Published

April 23, 2025

Author(s)

Jabir Marakkarakath Vadakkepurayil, Daehyun Ahn, Ivan Burenkov, Abdella Battou, Sergey Polyakov, N. Fajar R. Annafianto

Abstract

Optical phase stabilization, tracking, and locking in long fiber links are pivotal for the functionality of many communication protocols and distributed sensors. However, conventional phase stabilization methods use strong optical probe signals that may contaminate and destroy fragile quantum signals propagating in the same fiber link. Here, we experimentally demonstrate phase locking of fiber spools up to 100 km and over 120 km deployed optical communication link using faint coherent states with an average of just photons per second detected at the receiving detector as a probe signal. The power spectral density of phase noise, integrated from 1 Hz to 50 kHz, yields an excess rms phase noise of 110 mrad (corresponding to timing jitter below 0.09 fs) for a 100 km fiber spool and 140 mrad (corresponding to rms timing jitter below 0.12 fs) for deployed fiber. The displacement-enhanced measurement protocol that we employ for phase stabilization yields Fisher information that is greater than that of homodyne and heterodyne measurement protocols for fiber links longer than 100 m and, therefore, exceeds the canonical shot noise limit of accuracy. By implementing this stabilization strategy with a 50% duty cycle, we enable time-division multiplexed faint light and quantum payloads to coexist within the same communication channel.

Citation

Optica

Pub Type

Journals

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Keywords

Quantum network, Phase estimation, Phase stabilization

Citation

Marakkarakath Vadakkepurayil, J. , Ahn, D. , Burenkov, I. , Battou, A. , Polyakov, S. and R. Annafianto, N. (2025), Enabling phase stabilization of quantum networks via displacement-enhanced photon counting, Optica, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959105 (Accessed August 31, 2025)