Smooth optimal quantum control for robust solid state spin magnetometry

TL;DR

This paper introduces a Floquet theory-based method to generate smooth, robust quantum control pulses for NV center magnetometry, significantly enhancing sensitivity and robustness against imperfections.

Contribution

It presents a novel Floquet-based approach for designing smooth quantum control pulses that improve robustness and sensitivity in NV center magnetometry.

Findings

Enhanced magnetometry sensitivity by up to two orders of magnitude.

Demonstrated robustness of control pulses against inhomogeneities.

Applicable to various quantum technologies requiring high-fidelity control.

Abstract

Nitrogen-vacancy centers in diamond show great potential as magnetic, electric and thermal sensors which are naturally packaged in a bio-compatible material. In particular, NV-based magnetometers combine small sensor volumes with high sensitivities under ambient conditions. The practical operation of such sensors, however, requires advanced quantum control techniques that are robust with respect to experimental and material imperfections, control errors, and noise. Here, we present a novel approach that uses Floquet theory to efficiently generate smooth and simple quantum control pulses with tailored robustness properties. We verify their performance by applying them to a single NV center and by characterising the resulting quantum gate using quantum process tomography. We show how the sensitivity of NV-ensemble magnetometry schemes can be improved by up to two orders of magnitude by compensating for inhomogeneities in both the control field and the spin transition frequency. Our approach is ideally suited for a wide variety of quantum technologies requiring high-fidelity, robust control under tight bandwidth requirements, such as spin-ensemble based memories involving high-Q cavities.