Phase Independent Measurement of Weak Coherent Optical Signals
Abstract
We develop a quantum sensing framework for the phase independent detection of weak coherent optical displacements based on SU(1,1) interferometry. Unlike conventional quantum measurement protocols that require prior knowledge of the signal phase and coherent homodyne detection, the proposed approach estimates the displacement magnitude independently of its phase. We show that, under ideal lossless conditions, a conventional SU(1,1) interferometer employing only total intensity detection saturates the quantum Cramer Rao bound for displacement magnitude estimation. We further derive the analytical expression of the quantum Cramer Rao bound and the sensitivity of the conventional SU(1,1) interferometer with total intensity detection and systematically investigate its performance in the presence of optical loss. The proposed phase-independent intensity detection scheme achieves comparable performance over experimentally relevant operating regimes while eliminating the need for local oscillators, phase locking, and quadrature tracking. These results establish SU(1,1) based intensity detection as a practical platform for phase independent quantum sensing.
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BibTeX
@misc{chastain2026phase,
title = {{Phase Independent Measurement of Weak Coherent Optical Signals}},
author = {Lani Chastain and Priya Drashni and Mahadeva Chanda Durjoy and Hari P. Lamsal and Girish S. Agarwal and Tian Li},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.04363},
eprint = {2609.04363},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.04363},
}
RIS
TY - UNPB
TI - Phase Independent Measurement of Weak Coherent Optical Signals
AU - Lani Chastain
AU - Priya Drashni
AU - Mahadeva Chanda Durjoy
AU - Hari P. Lamsal
AU - Girish S. Agarwal
AU - Tian Li
PY - 2026
DA - 2026/09/03
PB - arXiv
DO - 10.48550/arxiv.2609.04363
UR - https://arxiv.org/abs/2609.04363
AB - We develop a quantum sensing framework for the phase independent detection of weak coherent optical displacements based on SU(1,1) interferometry. Unlike conventional quantum measurement protocols that require prior knowledge of the signal phase and coherent homodyne detection, the proposed approach estimates the displacement magnitude independently of its phase. We show that, under ideal lossless conditions, a conventional SU(1,1) interferometer employing only total intensity detection saturates the quantum Cramer Rao bound for displacement magnitude estimation. We further derive the analytical expression of the quantum Cramer Rao bound and the sensitivity of the conventional SU(1,1) interferometer with total intensity detection and systematically investigate its performance in the presence of optical loss. The proposed phase-independent intensity detection scheme achieves comparable performance over experimentally relevant operating regimes while eliminating the need for local oscillators, phase locking, and quadrature tracking. These results establish SU(1,1) based intensity detection as a practical platform for phase independent quantum sensing.
ER -