@inproceedings{2c8bbc9acd514bd688c0f89ea4509a08,
title = "Real-time displacement measurement with the ultimate quantum precision through spectrally resolved two-photon interference",
abstract = "We demonstrate real-time displacement measurement using spectrally resolved Hong–Ou–Mandel (HOM) interference that saturates the quantum Cram{\'e}r-Rao bound. Unlike conventional HOM-based methods, our approach does not require the displacement to be confined within the HOM dip width, typically a few tens of microns. By analyzing the periodicity of spectral interference fringes, we can maintain sensitivity at the quantum limit over displacement ranges extending to hundreds of microns. In principle, the measurable range can be extended up to the coherence length of the pump laser, limited only by the spectral resolution of the detector. We further demonstrate that real-time displacement tracking is feasible with current technology, establishing this technique as a practical and powerful tool for quantum-enhanced sensing and metrology.",
keywords = "Hong-Ou-Mandel interference, Quantum optics, Quantum sensing, Spectral entanglement, Spontaneous parametric down-conversion",
author = "Yingwen Zhang and Duncan England and Vincenzo Tamma and Ebrahim Karimi and Benjamin Sussman",
note = "Publisher Copyright: {\textcopyright} 2026 Published by SPIE.; 4th Quantum Sensing, Imaging, and Precision Metrology ; Conference date: 17-01-2026 Through 23-01-2026",
year = "2026",
month = mar,
day = "5",
doi = "10.1117/12.3080991",
language = "English",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
publisher = "SPIE Press",
editor = "Shahriar, \{Selim M.\}",
booktitle = "Quantum Sensing, Imaging, and Precision Metrology IV",
}