Coherence-Enhanced Single-Qubit Thermometry out of Equilibrium

Year: 2024

Authors: Frazao G., Pezzutto M., Omar Y., Cruzeiro EZ., Gherardini S.

Autors Affiliation: Univ Lisbon, Inst Super Tecn, P-1049001 Lisbon, Portugal; Inst Telecomunicacoes, P-1049001 Lisbon, Portugal; Ctr Fis & Engn Mat Avancados CeFEMA, Phys Informat & Quantum Technol Grp, P-1049001 Lisbon, Portugal; PQI Portuguese Quantum Inst, P-1600531 Lisbon, Portugal; Ist Nazl Ottica Consiglio Nazl Ric CNR INO, Largo Enrico Fermi 6, I-50125 Florence, Italy; Univ Firenze, European Lab Nonlinear Spect, I-50019 Sesto Fiorentino, Italy.

Abstract: The metrological limits of thermometry operated in nonequilibrium dynamical regimes are analyzed. We consider a finite-dimensional quantum system, employed as a quantum thermometer, in contact with a thermal bath inducing Markovian thermalization dynamics. The quantum thermometer is initialized in a generic quantum state, possibly including quantum coherence with respect to the Hamiltonian basis. We prove that the precision of the thermometer, quantified by the Quantum Fisher Information, is enhanced by the quantum coherence in its initial state. We analytically show this in the specific case of qubit thermometers for which the maximization of the Quantum Fisher Information occurs at a finite time during the transient thermalization dynamics. Such a finite-time precision enhancement can be better than the precision that is achieved asymptotically.

Journal/Review: ENTROPY

Volume: 26 (7)      Pages from: 568-1  to: 568-23

More Information: GF acknowledges support from FCT-Fundacao para a Ciencia e a Tecnologia (Portugal) through scholarship SFRH/BD/145572/2019. MP and SG wish to acknowledge financial support from the PRIN project 2022FEXLYB Quantum Reservoir Computing (QuReCo). SG also acknowledges the PNRR MUR project PE0000023-NQSTI funded by the European Union-NextGeneration EU. YO thanks the support from FCT through project UIDB/04540/2020. E.Z.C. ac-knowledges funding by FCT/MCTES-Fundacao para a Ciencia e a Te cnologia (Portugal)-through national funds and when applicable co-funding by EU funds under the project UIDB/50008/2020 and 2021.03707.CEECIND/CP1653/CT0002.
KeyWords: quantum thermodynamics; quantumm thermometry; quantum fisher information; generalized amplitude damping channel; quantum coherence; quantum simulation with optics
DOI: 10.3390/e26070568

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