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Heisenberg-limited metrology from the quantum-quench dynamics of an anisotropic ferromagnet

Z. M. McIntyre1,*, Ji Zou2,3,†, Jelena Klinovaja1, and Daniel Loss1,2,3,4

  • *Contact author: zoe.mcintyre@unibas.ch
  • †Contact author: ji.zou@unibas.ch
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Phys. Rev. Research 8, 043044 – Published 14 October, 2026

DOI: https://doi.org/10.1103/92jc-nlz8

Abstract

The emerging field of quantum magnonics seeks to understand and harness the quantum properties of magnons—quantized collective spin excitations in magnets. Squeezed magnon states arise naturally as the equilibrium ground states of anisotropic ferromagnets and antiferromagnets, representing an important class of nonclassical magnon states. In this work, we show how a qubit-conditioned quantum quench of an anisotropic ferromagnet can be used for Heisenberg-limited parameter estimation based on measurements of the qubit only. In the presence of ground-state squeezing, the protocol yields information about the eigenmode frequency of the coupled magnon-qubit system, whereas no information is gained in the absence of such squeezing. The protocol therefore leverages genuine quantum correlations in the form of magnonic squeezing while simultaneously relying on the equilibrium character of this squeezing—a feature distinctive to magnetic systems.

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Phys. Rev. Research 8, 043044– Published 14 October, 2026
  • Received 5 February 2026
  • Revised 28 May 2026
  • Accepted 23 September 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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