Quantum-amplified global-phase spectroscopy: a new spectroscopy protocol

I will present our development of global-phase spectroscopy, a Rabi-like metrological protocol inspired by geometric control techniques originally introduced for holonomic quantum gates and based on detuning-dependent Aharonov–Anandan phase. Applied to an optical clock transition, we deployed this method to realize quantum-amplified, time-reversal spectroscopy, yielding 2.4(7) dB metrological gain and 4.0(8) dB laser-noise suppression beyond the standard quantum limit. I will focus on the key metrological advantages of global-phase spectroscopy: i) an intrinsically favorable scaling of sensitivity to local-oscillator high-frequency noise (compared to for Rabi and for Ramsey), and, unlike standard Rabi spectroscopy, ii) featuring quantum enhancement when operated with entangled collective states, such as spin-squeezed inputs. I will close by connecting these results to the broader QIS-NP landscape, highlighting opportunities for applying this protocol to (other) nuclear-spin qubits, nuclear clocks, and other emerging quantum-enhanced sensing and quantum-information platforms.