Collective quantum enhancement in critical quantum sensing

TL;DR

This paper demonstrates that a chain of coupled critical resonators can achieve collective quantum enhancement in sensing, outperforming independent sensors, with robustness against nonlinearity and dissipation, relevant for current superconducting technologies.

Contribution

It introduces a multipartite critical quantum sensing protocol using coupled resonators, showing collective advantage and analytical solutions for the system's spectrum.

Findings

Quadratic scaling of quantum Fisher information with the number of resonators.

Coupled critical chain outperforms independent sensors.

Robustness against Kerr nonlinearity and dissipation.

Abstract

Critical systems represent a valuable resource in quantum sensing and metrology. Critical quantum sensing (CQS) protocols can be realized using finite-component phase transitions, where criticality arises from the rescaling of system parameters rather than the thermodynamic limit. Here, we show that a collective quantum advantage can be achieved in a multipartite CQS protocol using a chain of parametrically coupled critical resonators in the weak-nonlinearity limit. We derive analytical solutions for the low-energy spectrum of this unconventional quantum many-body system, which is composed of locally critical elements. We then assess the scaling of the quantum Fisher information with respect to fundamental resources. We demonstrate that the coupled chain outperforms an equivalent ensemble of independent critical sensors, achieving quadratic scaling in the number of resonators. Finally, we show that even with finite Kerr nonlinearity or Markovian dissipation, the critical chain retains its advantage, making it relevant for implementing quantum sensors with current microwave superconducting technologies.