Quantum Sensing using Geometrical Phase in Qubit-Oscillator Systems

TL;DR

This paper introduces a quantum sensing protocol that leverages geometrical phases in qubit-oscillator systems to achieve sensitivities beyond the standard quantum limit, with robustness to noise and independence from initial states.

Contribution

The authors develop a novel geometrical phase-based sensing method that surpasses the SQL and is applicable to various quantum systems, including high-temperature and error-corrected states.

Findings

Achieves sensitivities beyond the SQL in force sensing.

Demonstrates high-precision measurement capabilities in cQED systems.

Shows robustness to qubit Markovian noise and state-independence.

Abstract

We present a quantum sensing protocol for coupled qubit-oscillator systems that surpasses the standard quantum limit (SQL) by exploiting a geometrical phase. The signal is encoded in the geometrical phase that is proportional to the area enclosed in oscillator phase space. This area is amplified through squeezing, enabling sensitivities beyond the SQL. Our method is independent of oscillator's initial state, amenable to sensing with high-temperature or logical error-corrected states. The protocol shows robustness to qubit Markovian noise and preserves its state-independence, underscoring its practicality for next-generation quantum metrology. We demonstrate application to force sensing beyond the SQL in longitudinally coupled systems, and to high-precision measurements of couplings and pulse calibration surpassing SQL in dispersively coupled circuit quantum electrodynamics (cQED) architectures.