Quantum sensing via magnetic-noise-protected states in an electronic spin dyad

TL;DR

This paper proposes a theoretical approach to extend qubit coherence times using magnetic-noise-protected states in a hetero-spin system, enabling potential applications in nanoscale magnetometry and noise-free sensing.

Contribution

It introduces a novel spin dyad with energy level structures that support long-lived, magnetic-field-insensitive coherences for quantum sensing.

Findings

Identified pairs of energy levels with magnetic-field-insensitive transition frequencies.

Demonstrated that zero-quantum coherences are long-lived and selectively sensitive to local field fluctuations.

Suggested applications in nanoscale magnetometry and magnetic-noise-free electrometry.

Abstract

Extending the coherence lifetime of a qubit is central to the implementation and deployment of quantum technologies, particularly in the solid-state where various noise sources intrinsic to the material host play a limiting role. Here, we theoretically investigate the coherent spin dynamics of a hetero-spin system formed by a spin S=1 featuring a non-zero crystal field and in proximity to a paramagnetic center S'=1/2. We capitalize on the singular energy level structure of the dyad to identify pairs of levels associated to magnetic-field-insensitive transition frequencies, and theoretically show that the zero-quantum coherences we create between them can be remarkably long-lived. Further, we find these coherences are selectively sensitive to 'local' - as opposed to 'global' - field fluctuations, suggesting these spin dyads could be exploited as nanoscale gradiometers for precision magnetometry or as probes for magnetic-noise-free electrometry and thermal sensing.