Fisher-Information Recovery in Superconducting-Qubit Magnetometry with Squeezed-Microwave Readout
Abstract
The performance of superconducting-qubit magnetometers depends not only on magnetic-field encoding during Ramsey interrogation, but also on how efficiently the encoded information is recovered during readout. Squeezed microwaves provide a promising route to improve information extraction by suppressing readout noise, yet how such readout enhancement translates into accessible information for magnetic-field estimation remains unclear. Here we develop an effective detected-mode framework linking projected quadrature noise, state-assignment error, and the classical Fisher information accessible from binary readout outcomes. A finite mismatch between the squeezed quadrature and the discrimination axis produces an optimal squeezing strength through the competition between squeezed and anti-squeezed fluctuations. We further show that squeezed readout improves the readout-limited magnetic-field sensitivity by recovering information otherwise lost during state assignment, with the enhancement remaining robust against quadrature mismatch, transmission loss, and added noise. These results establish a quantitative connection between squeezed-microwave readout and measurement-stage information recovery in superconducting quantum sensing.
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BibTeX
@misc{yun2026fisherinformation,
title = {{Fisher-Information Recovery in Superconducting-Qubit Magnetometry with Squeezed-Microwave Readout}},
author = {M. -R. Yun and Y. -J. Qu and Zheng Shan and L. -L. Yan and Yu Jia and S. -L. Su},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.08598},
eprint = {2609.08598},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.08598},
}
RIS
TY - UNPB
TI - Fisher-Information Recovery in Superconducting-Qubit Magnetometry with Squeezed-Microwave Readout
AU - M. -R. Yun
AU - Y. -J. Qu
AU - Zheng Shan
AU - L. -L. Yan
AU - Yu Jia
AU - S. -L. Su
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.08598
UR - https://arxiv.org/abs/2609.08598
AB - The performance of superconducting-qubit magnetometers depends not only on magnetic-field encoding during Ramsey interrogation, but also on how efficiently the encoded information is recovered during readout. Squeezed microwaves provide a promising route to improve information extraction by suppressing readout noise, yet how such readout enhancement translates into accessible information for magnetic-field estimation remains unclear. Here we develop an effective detected-mode framework linking projected quadrature noise, state-assignment error, and the classical Fisher information accessible from binary readout outcomes. A finite mismatch between the squeezed quadrature and the discrimination axis produces an optimal squeezing strength through the competition between squeezed and anti-squeezed fluctuations. We further show that squeezed readout improves the readout-limited magnetic-field sensitivity by recovering information otherwise lost during state assignment, with the enhancement remaining robust against quadrature mismatch, transmission loss, and added noise. These results establish a quantitative connection between squeezed-microwave readout and measurement-stage information recovery in superconducting quantum sensing.
ER -