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arXiv · 2211.07688

Critical quantum metrology assisted by real-time feedback control

Raffaele Salvia·Mohammad Mehboudi·Martí Perarnau-Llobet
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Abstract

We investigate critical quantum metrology,that is the estimation of parameters in many-body systems close to a quantum critical point, through the lens of Bayesian inference theory. We first derive a no-go result stating that any non-adaptive measurement strategy will fail to exploit quantum critical enhancement (i.e. precision beyond the shot-noise limit) for a sufficiently large number of particles $N$ whenever our prior knowledge is limited. We then consider different adaptive strategies that can overcome this no-go result, and illustrate their performance in the estimation of (i) a magnetic field using a probe of 1D spin Ising chain and (ii) the coupling strength in a Bose-Hubbard square lattice. Our results show that adaptive strategies with real-time feedback control can achieve sub-shot noise scaling even with few measurements and substantial prior uncertainty.

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Raffaele Salvia, Mohammad Mehboudi, Martí Perarnau-Llobet. 2022-11-14. Critical quantum metrology assisted by real-time feedback control. https://doi.org/10.1103/physrevlett.130.240803

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