arXiv subjects

E. Lilette

Publications and source records attributed to E. Lilette.

2 recordsLinked to original sources

arXiv2018

$T_2$-limited sensing of static magnetic fields via fast rotation of quantum spins

Diamond-based quantum magnetometers are more sensitive to oscillating (AC) magnetic fields than static (DC) fields because the crystal impurity-induced ensemble dephasing time $T_2^*$, the relevant sensing time for a DC field, is much shorter than the spin coherence time $T_2$, which determines the sensitivity to AC fields. Here we demonstrate measurement of DC magnetic fields using a physically rotating ensemble of nitrogen-vacancy centres at a precision ultimately limited by $T_2$ rather than $T_2^*$. The rotation period of the diamond is comparable to $T_2$ and the angle between the NV axis and the target magnetic field changes as a function of time, thus upconverting the static magnetic field to an oscillating field in the physically rotating frame. Using spin-echo interferometry of the rotating NV centres, we are able to perform measurements for over a hundred times longer compared to a conventional Ramsey experiment. With modifications our scheme could realise DC sensitivities equivalent to demonstrated NV center AC magnetic field sensitivities of order $0.1$\,nT\,Hz$^{-1/2}$.

quant-ph↗

arXiv2017

Magnetic pseudo-fields in a rotating electron-nuclear spin system

A precessing spin observed in a rotating frame of reference appears frequency-shifted, an effect analogous to the precession of a Foucault pendulum observed on the rotating Earth. This frequency shift can be understood as arising from a magnetic pseudo-field in the rotating frame that nevertheless has physically significant consequences, such as the Barnett effect. Detecting these pseudo-fields is experimentally challenging, as a rotating-frame sensor is required. Previous work has realised classical rotating-frame detectors. Here we use quantum sensors, nitrogen-vacancy (NV) centres, in a rapidly rotating diamond to detect pseudo-fields in the rotating frame. While conventional magnetic fields induce precession at a rate proportional to the gyromagnetic ratio, rotation shifts the precession of all spins equally, and thus primarily affect nearby $^{13}$C nuclear spins. We are thus able to explore these effects via quantum sensing in a rapidly rotating frame, and define a new approach to quantum control using rotationally-induced nuclear spin-selective magnetic fields. This work provides an integral step towards realising precision rotation sensing and quantum spin gyroscopes.

quant-ph↗