Universality in fidelity-based quantum metrology

Fuente: arXiv
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Main Authors: Aragón-Muñoz, Luis, Chryssomalakos, Chryssomalis, Flores-Delgado, Ana Gabriela, Martin, John, Serrano-Ensástiga, Eduardo
Format: Preprint
Published: 2025
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author Aragón-Muñoz, Luis
Chryssomalakos, Chryssomalis
Flores-Delgado, Ana Gabriela
Martin, John
Serrano-Ensástiga, Eduardo
author_facet Aragón-Muñoz, Luis
Chryssomalakos, Chryssomalis
Flores-Delgado, Ana Gabriela
Martin, John
Serrano-Ensástiga, Eduardo
contents We consider the problem of identifying the quantum spin states that are the optimal sensors of a given transformation averaged over all possible orientations of the spin system. Our geometric approach to the problem is based on a fidelity criterion and is entirely general, encompassing both unitary transformations (such as rotations and squeezing) and non-unitary transformations (such as Lorentz boosts). This formalism leads to a universality result: There exists a zero-measure subset of states that will be optimal sensors for certain transformations and the worst sensors for others, and this set does not depend on the transformation under consideration. In other words, some spin states are simply the best (or worst) sensors, regardless of what they detect.
format Preprint
id arxiv_https___arxiv_org_abs_2509_18533
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Universality in fidelity-based quantum metrology
Aragón-Muñoz, Luis
Chryssomalakos, Chryssomalis
Flores-Delgado, Ana Gabriela
Martin, John
Serrano-Ensástiga, Eduardo
Quantum Physics
We consider the problem of identifying the quantum spin states that are the optimal sensors of a given transformation averaged over all possible orientations of the spin system. Our geometric approach to the problem is based on a fidelity criterion and is entirely general, encompassing both unitary transformations (such as rotations and squeezing) and non-unitary transformations (such as Lorentz boosts). This formalism leads to a universality result: There exists a zero-measure subset of states that will be optimal sensors for certain transformations and the worst sensors for others, and this set does not depend on the transformation under consideration. In other words, some spin states are simply the best (or worst) sensors, regardless of what they detect.
title Universality in fidelity-based quantum metrology
topic Quantum Physics
url https://arxiv.org/abs/2509.18533