Unambiguous measurement in an unshielded microscale magnetometer with sensitivity below 1 pT/rHz

Fuente: arXiv
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Auteurs principaux: Taylor, Hamish A. M., Bounds, Christopher C., Tritt, Alex, Turner, L. D.
Format: Preprint
Publié: 2023
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author Taylor, Hamish A. M.
Bounds, Christopher C.
Tritt, Alex
Turner, L. D.
author_facet Taylor, Hamish A. M.
Bounds, Christopher C.
Tritt, Alex
Turner, L. D.
contents Cold atom magnetometers exploit a dense ensemble of quanta with long coherence times to realise leading sensitivity on the micrometer scale. Configured as a Ramsey interferometer, a cold atom sensor can approach atom shot-noise limited precision but suffers from fringe ambiguity, producing gross errors when the field falls outside a narrow predefined range. We describe how Hilbert-demodulated optical magnetometry can be realised on cold atom sensors to provide field measurements both precise and unambiguous. Continuous reconstruction of the Larmor phase allows us to determine the dc magnetic field unambiguously in an unshielded environment, as well as measure ac variation of the field, in a single shot. The ac measurement allows us to characterize, and then neutralise, line-synchronous magnetic interference, extending reconstruction times. Using $1.6 \times 10^6$ $^{87}$Rb atoms in a volume of $(68 \,\mathrm{μm})^3$, we measure a test field to be $ 86.0121261(4) \; \mathrm{μT}$ in a single shot, achieving dc sensitivity of 380 fT in a duration of 1000 ms. Our results demonstrate that Hilbert-demodulated optical readout yields metrologically-significant sensitivity without the fringe ambiguity inherent to Ramsey interferometry.
format Preprint
id arxiv_https___arxiv_org_abs_2309_11825
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Unambiguous measurement in an unshielded microscale magnetometer with sensitivity below 1 pT/rHz
Taylor, Hamish A. M.
Bounds, Christopher C.
Tritt, Alex
Turner, L. D.
Quantum Physics
Cold atom magnetometers exploit a dense ensemble of quanta with long coherence times to realise leading sensitivity on the micrometer scale. Configured as a Ramsey interferometer, a cold atom sensor can approach atom shot-noise limited precision but suffers from fringe ambiguity, producing gross errors when the field falls outside a narrow predefined range. We describe how Hilbert-demodulated optical magnetometry can be realised on cold atom sensors to provide field measurements both precise and unambiguous. Continuous reconstruction of the Larmor phase allows us to determine the dc magnetic field unambiguously in an unshielded environment, as well as measure ac variation of the field, in a single shot. The ac measurement allows us to characterize, and then neutralise, line-synchronous magnetic interference, extending reconstruction times. Using $1.6 \times 10^6$ $^{87}$Rb atoms in a volume of $(68 \,\mathrm{μm})^3$, we measure a test field to be $ 86.0121261(4) \; \mathrm{μT}$ in a single shot, achieving dc sensitivity of 380 fT in a duration of 1000 ms. Our results demonstrate that Hilbert-demodulated optical readout yields metrologically-significant sensitivity without the fringe ambiguity inherent to Ramsey interferometry.
title Unambiguous measurement in an unshielded microscale magnetometer with sensitivity below 1 pT/rHz
topic Quantum Physics
url https://arxiv.org/abs/2309.11825