High precision single qubit tuning via thermo-magnetic field control

TL;DR

This paper introduces a precise, thermally controlled magnetic field tuning method for single NV center qubits, significantly enhancing frequency stability for quantum sensing and hyperpolarisation applications.

Contribution

A novel technique using temperature-controlled magnetisation to finely tune magnetic fields for NV center qubits, improving stability and enabling advanced quantum sensing.

Findings

Achieved an order of magnitude improvement in NV qubit frequency stability.

Performed nanoscale cross-relaxation spectroscopy of electron and nuclear spins.

Demonstrated potential for portable quantum sensing and hyperpolarisation systems.

Abstract

Precise control of the resonant frequency of a spin qubit is of fundamental importance to quantum sensing protocols. We demonstrate a control technique on a single nitrogen-vacancy (NV) centre in diamond where the applied magnetic field is modified by fine-tuning a permanent magnet's magnetisation via temperature control. Through this control mechanism, nanoscale cross-relaxation spectroscopy of both electron and nuclear spins in the vicinity of the NV centre are performed. We then show that through maintaining the magnet at a constant temperature an order of magnitude improvement in the stability of the NV qubit frequency can be achieved. This improved stability is tested in the polarisation of a small ensemble of nearby $^{13}$C spins via resonant cross-relaxation and the lifetime of this polarisation explored. The effectiveness and relative simplicity of this technique may find use in the realisation of portable spectroscopy and/or hyperpolarisation systems.