Collective quantum enhancement in critical quantum sensing

• Main Authors: Alushi, Uesli, Coppo, Alessandro, Brosco, Valentina, Di Candia, Roberto, Felicetti, Simone
• Format: Journal Article
• Language: English
• Published: 25-07-2024
• Subjects: Physics - Mesoscale and Nanoscale Physics; Physics - Quantum Physics
• DOI: 10.48550/arxiv.2407.18055

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 is not due to the
thermodynamic limit but rather to the rescaling of the system parameters. In
particular, the second-order phase transitions of parametric Kerr resonators
are of high experimental relevance, as they can be implemented and controlled
with various quantum technologies currently available. Here, we show that
collective quantum advantage can be achieved with a multipartite critical
quantum sensor based on a parametrically coupled Kerr resonators chain 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
\emph{locally} critical elements. We then assess the performance of an
adiabatic CQS protocol, comparing the coupled-resonator chain with an
equivalent ensemble of independent critical sensors. We evaluate the scaling of
the quantum Fisher information with respect to fundamental resources, and find
that the critical chain achieves a quadratic enhancement in the number of
resonators. Beyond the advantage found in the case of zero Kerr, we find that
there is a collective enhancement even in the scenario of finite Kerr
nonlinearity.