Dynamical decoupling based quantum sensing: Floquet spectroscopy

TL;DR

This paper introduces Floquet spectroscopy as a versatile method for analyzing quantum sensing experiments involving nuclear spins, providing insights into complex many-body dynamics and strong coupling regimes without requiring resonant driving.

Contribution

The paper presents Floquet spectroscopy as a general framework for quantum sensing analysis, extending capabilities to complex, many-body, and strongly coupled systems with finite-duration pulses.

Findings

Floquet spectroscopy offers physical insight into coherence decay features.

Application to NV-centers reveals characteristic 'diamond' features.

Potential for highly tunable sensors in silicon donors.

Abstract

Sensing the internal dynamics of individual nuclear spins or clusters of nuclear spins has recently become possible by observing the coherence decay of a nearby electronic spin: the weak magnetic noise is amplified by a periodic, multi-pulse decoupling sequence. However, it remains challenging to robustly infer underlying atomic-scale structure from decoherence traces in all but the simplest cases. We introduce Floquet spectroscopy as a versatile paradigm for analysis of these experiments, and argue it offers a number of general advantages. In particular, this technique generalises to more complex situations, offering physical insight in regimes of many-body dynamics, strong coupling and pulses of finite duration. As there is no requirement for resonant driving, the proposed spectroscopic approach permits physical interpretation of striking, but overlooked, coherence decay features in terms of the form of the avoided crossings of the underlying quasienergy eigenspectrum. This is exemplified by a set of "diamond" shaped features arising for transverse-field scans in the case of single-spin sensing by NV-centers in diamond. We investigate also applications for donors in silicon showing that the resulting tunable interaction strengths offer highly promising future sensors.