Spin readout via spin-to-charge conversion in bulk diamond nitrogen-vacancy ensembles

TL;DR

This paper demonstrates an improved optical readout method for NV center spins in bulk diamond using spin-to-charge conversion, resulting in higher sensitivity and faster measurement speeds for quantum sensing applications.

Contribution

It introduces a spin-to-charge conversion technique with a 594 nm laser for ensemble NV centers, enhancing readout contrast and measurement speed over conventional methods.

Findings

Achieved up to 12% contrast in spin-to-charge conversion.

Tenfold increase in sensing measurement speed.

Performance limited by ionization and laser powers.

Abstract

We demonstrate optical readout of ensembles of nitrogen-vacancy(NV) center spins in a bulk diamond sample via spin-to-charge conversion. A high power 594 nm laser is utilized to selectively ionize these paramagnetic defects in the spin state with a contrast of up to 12%. In comparison with the conventional 520 nm spin readout, spin-to-charge-conversion-based readout provides higher signal-to-noise ratio, with tenfold sensing measurement speedup for millisecond long pulse sequences. This level of performance was achieved for an NV- ionization of only 25%, limited by the ionization and readout laser powers. These observations pave the way to a range of high-sensitivity metrology applications where the use of NV- ensembles in bulk diamond has proven useful, including sensing and imaging of target materials overlaid on the diamond surface.