Noise reduction in optically pumped magnetometer assemblies

Schultze, V.; IJsselsteijn, R.P.J.; Meyer, H.‐G.

doi:10.1007/s00340-010-4084-9

Cited by 22 publications

(17 citation statements)

References 19 publications

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“…The rf field is applied parallel to the propagation direction of the probe light by a pair of Helmholtz coils. The ambient static magnetic field is controlled in magnitude and direction by a triaxial Helmholtz-coil system that is placed inside a threefold cylindrical μ-metal magnetic shield [19]. The cell temperature is set by exposing the lateral silicon parts of the cell array to fiber-coupled heating laser radiation (λ = 808 nm) [34] and gets monitored by a nonmagnetic fiber-optical sensor thermally connected to the cell's bulk silicon.…”

Section: A Experimental Setupmentioning

confidence: 99%

“…As a consequence OPMs with record-breaking sensitivities were developed [13,16]. Additionally, the ability to improve the sensitivity per unit cell volume allows for miniaturization of magnetometer cells without a great sacrifice in sensitivity [17,18], which simultaneously offers several advantages such as the reduced influence of magnetic field gradients, compactness of the sensor head and the possibility of a tight spacing of several identical cells for mutual referencing [19] or highly sensitive magnetic-field imaging [20,21]. Modern OPMs find application in fields ranging from magnetocardiography [22] and magnetoencephalography [21,23] through magnetorelaxometry of nanoparticles [24] to tests of fundamental physics [25].…”

Section: Introductionmentioning

confidence: 99%

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Suppression of spin-exchange relaxation in tilted magnetic fields within the geophysical range

et al. 2016

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We present a detailed experimental and theoretical study on the relaxation of spin coherence due to the spin-exchange mechanism arising in the electronic ground states of alkali-metal vapor atoms. As opposed to the well-explored formation of a stretched state in a longitudinal geometry (magnetic field parallel to the laser propagation direction) we employ adapted hyperfine-selective optical pumping in order to suppress spin-exchange relaxation. By comparing measurements of the intrinsic relaxation rate of the spin coherence in the ground state of cesium atoms with detailed density-matrix simulations we show that the relaxation due to spin-exchange collisions can be reduced substantially even in a tilted magnetic field of geomagnetic strength, the major application case of scalar magnetic surveying. This explains the observed striking improvement in sensitivity and further deepens the understanding of the light-narrowed M x magnetometer, which was presented recently. Additionally, new avenues for investigating the dynamics in alkali-metal atoms governed by the spin-exchange interaction and interacting with arbitrary external fields open up.

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Section: A Experimental Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Suppression of spin-exchange relaxation in tilted magnetic fields within the geophysical range

et al. 2016

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“…Ways to suppress or even eliminate additional noise contribution emerging from the light-shift coupling of laser intensity fluctuations directly to Larmor frequency fluctuations are subjects of further investigations starting with a gradiometric sensor design. The gradiometer or reference cell approach is also expected to get rid of the other common magnetometer noise sources and to bring the signal noise floor close to the shot-noise limit [8].…”

Section: Discussionmentioning

confidence: 99%

“…(1) suggests large cell volume to achieve best sensitivity, we use miniaturized cavities in microfabricated cell arrays as the central sensor element [5], technologically based on recent developments of miniaturized atomic clocks and magnetometers at the National Institute of Standards and Technology (NIST) [6,7]. Several arguments like future batch production with reproducible parameters, the possibility of small spacing of (possibly connected) neighboring cells (to form well-matched gradiometers or to introduce reference cells for noise reduction [8]), or keeping external magnetic field gradients over the cell volume and between two cells as small as possible count for that strategy. According to Eq.…”

Section: Introductionmentioning

confidence: 99%

Light-narrowed optically pumpedMxmagnetometer with a miniaturized Cs cell

et al. 2011

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We demonstrate a way of operating an optically pumped magnetometer with miniaturized cesium cell using the light-narrowing effect. The magnetometer setup shows improvement of shot-noise-limited sensitivity (42 fT/ √ Hz in a cell of only 9.3 mm 3 volume) due to the suppression of spin-exchange relaxation to a large extent and the use of a strikingly increased fraction of alkali-metal atoms for signal generation, working even in μT magnetic fields, by using only a single high-intensity laser beam both for pumping and probing of atomic spins.

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“…Similar dual-beam difference noise suppression techniques have been developed for atomic clocks and other configurations of optical magnetometers [17][18][19]. And similar control loops for intensity noise "eating" have been developed [20].…”

Section: Introductionmentioning

confidence: 98%

Spin-exchange relaxation-free magnetic gradiometer with dual-beam and closed-loop Faraday modulation

et al. 2014

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Spin-exchange relaxation-free (SERF) atomic magnetometers usually adopt Faraday modulation to achieve better performance but suffer from laser intensity noise, thermal noise generated by the Faraday modulator, and nonmagnetic technical noise. These noises limit the sensitivity of the SERF magnetometer. We demonstrate a SERF magnetic gradiometer with dual-beam and closed-loop Faraday modulation. Operating in the SERF regime, the gradiometer utilizes an additional Faraday modulator rotation feedback to suppress probe laser intensity noise and thermal noise associated with the Faraday modulator, and it simultaneously uses dual-beam difference to cancel common-mode nonmagnetic technical noises. A gradient sensitivity of 14 fT∕Hz 1∕2 per 1 cm gradiometer base length was achieved using Cs atoms.

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Noise reduction in optically pumped magnetometer assemblies

Cited by 22 publications

References 19 publications

Suppression of spin-exchange relaxation in tilted magnetic fields within the geophysical range

Suppression of spin-exchange relaxation in tilted magnetic fields within the geophysical range

Light-narrowed optically pumpedMxmagnetometer with a miniaturized Cs cell

Spin-exchange relaxation-free magnetic gradiometer with dual-beam and closed-loop Faraday modulation

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