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arXiv · 2207.11009

A Digital Alkali Spin Maser

Stuart Ingleby·Paul Griffin·Terry Dyer·Marcin Mrozowski·Erling Riis
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Abstract

Self-oscillating atomic magnetometers, in which the precession of atomic spins in a magnetic field is driven by resonant modulation, offer high sensitivity and dynamic range. Phase-coherent feedback from the detected signal to the applied modulation creates a resonant spin maser system, highly responsive to changes in the background magnetic field. Here we show a system in which the phase condition for resonant precession is met by digital signal processing integrated into the maser feedback loop. This system uses a modest chip-scale laser and mass-produced dual-pass caesium vapour cell and operates in a 50 microtesla field, making it a suitable technology for portable measurements of the geophysical magnetic field. We demonstrate a Cramer-Rao lower bound-limited resolution of 50 fT at 1 s sampling cadence, and a sensor bandwidth of 10 kHz. This device also represents an important class of atomic system in which low-latency digital processing forms an integral part of a coherently-driven quantum system.

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Stuart Ingleby, Paul Griffin, Terry Dyer, Marcin Mrozowski, Erling Riis. 2022-07-22. A Digital Alkali Spin Maser. https://arxiv.org/abs/2207.11009

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