2 research outputs found
Vector DC magnetic-field sensing with reference microwave field using perfectly aligned nitrogen-vacancy centers in diamond
The measurement of vector magnetic fields with high sensitivity and spatial
resolution is important for both fundamental science and engineering
applications. In particular, magnetic-field sensing with nitrogen-vacancy (NV)
centers in diamond is a promising approach that can outperform existing
methods. Recent studies have demonstrated vector DC magnetic-field sensing with
perfectly aligned NV centers, which showed a higher readout contrast than NV
centers having four equally distributed orientations. However, to estimate the
azimuthal angle of the target magnetic field with respect to the NV axis in
these previous approaches, it is necessary to apply a strong reference DC
magnetic field, which can perturb the system to be measured. This is a crucial
problem, especially when attempting to measure vector magnetic fields from
materials that are sensitive to applied DC magnetic fields. Here, we propose a
method to measure vector DC magnetic fields using perfectly aligned NV centers
without reference DC magnetic fields. More specifically, we used the direction
of linearly polarized microwave fields to induce Rabi oscillation as a
reference and estimated the azimuthal angle of the target fields from the Rabi
frequency. We further demonstrate the potential of our method to improve
sensitivity by using entangled states to overcome the standard quantum limit.
Our method of using a reference microwave field is a novel technique for
sensitive vector DC magnetic-field sensing.Comment: 10 pages, 8 figure
A many-body singlet prepared by a central spin qubit
Controllable quantum many-body systems are platforms for fundamental
investigations into the nature of entanglement and promise to deliver
computational speed-up for a broad class of algorithms and simulations. In
particular, engineering entanglement within a dense spin ensemble can turn it
into a robust quantum memory or a computational platform. Recent experimental
progress in dense central spin systems motivates the design of algorithms that
use a central-spin qubit as a convenient proxy for the ensemble. Here we
propose a protocol that uses a central spin to initialize two dense spin
ensembles into a pure anti-polarized state and from there creates a many-body
entangled state -- a singlet -- from the combined ensemble. We quantify the
protocol performance for multiple material platforms and show that it can be
implemented even in the presence of realistic levels of decoherence. Our
protocol introduces an algorithmic approach to preparation of a known many-body
state and to entanglement engineering in a dense spin ensemble, which can be
extended towards a broad class of collective quantum states.Comment: 11 pages, 6 figures, and supplementary material