Magnetotactic bacterial populations studied with a Pound-Drever-Hall atomic magnetometer

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Autori principali: Ruiz, María Hernández, Kiehl, Christopher, Lucivero, Vito Giovanni, Mitchell, Morgan W.
Natura: Preprint
Pubblicazione: 2025
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author Ruiz, María Hernández
Kiehl, Christopher
Lucivero, Vito Giovanni
Mitchell, Morgan W.
author_facet Ruiz, María Hernández
Kiehl, Christopher
Lucivero, Vito Giovanni
Mitchell, Morgan W.
contents We demonstrate an optically pumped magnetometer that monitors spin polarization using Pound Drever Hall (PDH) technique. The instrument exhibits a noise floor of 22.2 pT/sqrt(Hz) limited by optical photon shot noise, short-term instability of 30.8 pT/sqrt(Hz)/sqrt(τ) for averaging times τ < 0.2 s , instability below 70 pT for 0.2 s < τ < 20 s and a minimum instability of 47 pT at τ = 6 s. We apply the OPM to investigate the ability of magnetotactic bacteria (Magnetospirillum gryphiswaldense, MSR-1) to orient in externally applied magnetic fields. Observing an opaque, concentrated suspension, we detect deviations from exponential relaxation dynamics on second time-scales, which give information about the dispersion of bacterial magnetic moment and rotational damping coefficient. These parameters are observed to evolve as the population further concentrates due to evaporation and settling. To our knowledge, this is the first time such magnetic inhomogeneities and long-term relaxation deviations have been directly observed. This study showcases both the sensitivity and stability of our OPM and its potential for probing biophysical processes.
format Preprint
id arxiv_https___arxiv_org_abs_2510_09419
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Magnetotactic bacterial populations studied with a Pound-Drever-Hall atomic magnetometer
Ruiz, María Hernández
Kiehl, Christopher
Lucivero, Vito Giovanni
Mitchell, Morgan W.
Atomic Physics
Quantum Physics
We demonstrate an optically pumped magnetometer that monitors spin polarization using Pound Drever Hall (PDH) technique. The instrument exhibits a noise floor of 22.2 pT/sqrt(Hz) limited by optical photon shot noise, short-term instability of 30.8 pT/sqrt(Hz)/sqrt(τ) for averaging times τ < 0.2 s , instability below 70 pT for 0.2 s < τ < 20 s and a minimum instability of 47 pT at τ = 6 s. We apply the OPM to investigate the ability of magnetotactic bacteria (Magnetospirillum gryphiswaldense, MSR-1) to orient in externally applied magnetic fields. Observing an opaque, concentrated suspension, we detect deviations from exponential relaxation dynamics on second time-scales, which give information about the dispersion of bacterial magnetic moment and rotational damping coefficient. These parameters are observed to evolve as the population further concentrates due to evaporation and settling. To our knowledge, this is the first time such magnetic inhomogeneities and long-term relaxation deviations have been directly observed. This study showcases both the sensitivity and stability of our OPM and its potential for probing biophysical processes.
title Magnetotactic bacterial populations studied with a Pound-Drever-Hall atomic magnetometer
topic Atomic Physics
Quantum Physics
url https://arxiv.org/abs/2510.09419