Geometric Invariants of Quantum Metrology

Fuente: arXiv
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Auteurs principaux: Wilson, Christopher, Wilson, John Drew, Coffman, Luke, Alam, Shah Saad, Holland, Murray J.
Format: Preprint
Publié: 2025
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author Wilson, Christopher
Wilson, John Drew
Coffman, Luke
Alam, Shah Saad
Holland, Murray J.
author_facet Wilson, Christopher
Wilson, John Drew
Coffman, Luke
Alam, Shah Saad
Holland, Murray J.
contents We establish a previously unexplored conservation law for the Quantum Fisher Information Matrix (QFIM) expressed as follows; when the QFIM is constructed from a set of observables closed under commutation, i.e., a Lie algebra, the spectrum of the QFIM is invariant under unitary dynamics generated by these same operators. Each Lie algebra therefore endows any quantum state with a fixed "budget" of metrological sensitivity -- an intrinsic resource that we show, like optical squeezing in interferometry, cannot be amplified by symmetry-preserving operations. The Uhlmann curvature tensor (UCT) naturally inherits the same symmetry group, and so quantum incompatibility is similarly fixed. As a result, a metrological analog to Liouville's theorem appears; statistical distances, volumes, and curvatures are invariant under the evolution generated by the Lie algebra. We discuss this as it relates to the quantum analogs of classical optimality criteria. This enables one to efficiently classify useful classes of quantum states at the level of Lie algebras through geometric invariants.
format Preprint
id arxiv_https___arxiv_org_abs_2507_06128
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Geometric Invariants of Quantum Metrology
Wilson, Christopher
Wilson, John Drew
Coffman, Luke
Alam, Shah Saad
Holland, Murray J.
Quantum Physics
Atomic Physics
We establish a previously unexplored conservation law for the Quantum Fisher Information Matrix (QFIM) expressed as follows; when the QFIM is constructed from a set of observables closed under commutation, i.e., a Lie algebra, the spectrum of the QFIM is invariant under unitary dynamics generated by these same operators. Each Lie algebra therefore endows any quantum state with a fixed "budget" of metrological sensitivity -- an intrinsic resource that we show, like optical squeezing in interferometry, cannot be amplified by symmetry-preserving operations. The Uhlmann curvature tensor (UCT) naturally inherits the same symmetry group, and so quantum incompatibility is similarly fixed. As a result, a metrological analog to Liouville's theorem appears; statistical distances, volumes, and curvatures are invariant under the evolution generated by the Lie algebra. We discuss this as it relates to the quantum analogs of classical optimality criteria. This enables one to efficiently classify useful classes of quantum states at the level of Lie algebras through geometric invariants.
title Geometric Invariants of Quantum Metrology
topic Quantum Physics
Atomic Physics
url https://arxiv.org/abs/2507.06128