June 30, 2025 to July 4, 2025
Europe/Vienna timezone

Coupled atom-cavity systems for quantum-enhanced metrology: adiabatic elimination of the cavity mode beyond the leading order

Jun 30, 2025, 3:15 PM
1h 45m
Poster Fundamental physics, precision measurements, atom interferometry and atomic clocks Poster Session 1

Speaker

Stefano Gregorio Giaccari (Istituto Nazionale di Ricerca Metrologica (INRiM))

Description

Spin-squeezed states are a prototypical example of metrologically useful states where structured entanglement allows for enhanced sensing with respect to the one possible using classically correlated particles. Relevant aspects are both the efficient preparation of spin-squeezed states and the scalability of estimation precision with the number $N$ of probes. Recently, in the context of the generation of spin-squeezed states via coupling of three-level atoms to an optical cavity and continuous quantum measurement of the transmitted cavity field, it was shown that increasing the atom-cavity coupling can be detrimental to spin-squeezing generation, an effect that is not appreciated in the standard second-order cavity removal approximation [1]. We describe adiabatic elimination techniques to derive an effective Lindblad master equation up to third order in the collective spin operators. We then discuss two approaches to the solution of this equation: a very general one based on a systematic implementation of the truncated cumulant expansion and its numerical solution, which allows to show that the mean field and Gaussian approximations are inadequate to predict the correct spin-squeezing scaling, and a fully analytic one leveraging on the existence of a complete set of commuting weak symmetries [2].

References

[1] A. Caprotti, M. Barbiero, M. G. Tarallo, M. G. Genoni and G. Bertaina, Quantum Sci. Technol., 9, no.3, (2024) 035032
[2] S. G. Giaccari, G. Dellea, M. G. Genoni and G. Bertaina, in preparation

Authors

Gianluca Bertaina (Istituto Nazionale di Ricerca Metrologica (INRiM)) Giulia Dellea (Università degli Studi di Milano) Marco G. Genoni (Università degli Studi di Milano) Marco G. Tarallo (Istituto Nazionale di Ricerca Metrologica (INRiM)) Stefano Gregorio Giaccari (Istituto Nazionale di Ricerca Metrologica (INRiM))

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