Quantum Enhanced Sensitivity through Many-Body Bloch Oscillations

TL;DR

This paper explores how quantum many-body systems with Bloch oscillations can be used for highly sensitive measurements, revealing phase-dependent scaling of quantum Fisher information and the impact of interactions on sensing precision.

Contribution

It provides a quantitative framework for quantum Fisher information in many-body systems, highlighting phase-dependent scaling and the effects of interactions on quantum sensing.

Findings

Quantum Fisher information scales quadratically with time, approaching the Heisenberg limit.

Extended phase exhibits quantum-enhanced size scaling, localized phase does not.

Increasing excitations improves precision, but interactions induce localization reducing this benefit.

Abstract

We investigate the sensing capacity of non-equilibrium dynamics in quantum systems exhibiting Bloch oscillations. By focusing on the resource efficiency of the probe, quantified by quantum Fisher information, we find different scaling behaviors in two different phases, namely localized and extended. Our results provide a quantitative ansatz for quantum Fisher information in terms of time, probe size, and the number of excitations. In the long-time regime, the quantum Fisher information is a quadratic function of time, touching the Heisenberg limit. The system size scaling drastically depends on the phase changing from quantum-enhanced scaling in the extended phase to size-independent behavior in the localized phase. Furthermore, increasing the number of excitations always enhances the precision of the probe, although, in the interacting systems the enhancement becomes less eminent than the non-interacting probes. This is due to the induced localization by increasing the interaction between the excitations. We show that a simple particle configuration measurement together with a maximum likelihood estimation can closely reach the ultimate precision limit in both single- and multi-particle probes.