Interference in Atomic Magnetometry

Abstract

Atomic magnetometers are highly sensitive detectors of magnetic fields that monitor the evolution of the macroscopic magnetic moment of atomic vapors, and opening new applications in biological, physical, and chemical science. However, the performance of atomic magnetometers is often limited by hidden systematic effects that may cause misdiagnosis for a variety of applications, for example, in nuclear magnetic resonance (NMR) and in biomagnetism. In this work, a hitherto unexplained interference effect in atomic magnetometers is uncovered, which causes an important systematic effect to greatly deteriorate the accuracy of measuring magnetic fields. A standard approach to detecting and characterizing the interference effect in, but not limited to, atomic magnetometers is presented. As applications of the work, the effect of the interference in NMR structural determination and locating the brain electrophysiological symptom is considered, and it is shown that it will help to improve the measurement accuracy by taking interference effects into account. Through the experiments, good agreement is indeed found between the prediction and the asymmetric amplitudes of resonant lines in ultralow-field NMR spectra-an effect that has not been understood so far. It is anticipated that the work will stimulate interesting new researches for magnetic interference phenomena in a wide range of magnetometers and their applications.

Limits on axions and axionlike particles within the axion window using a spin-based amplifier

“…In this Letter, we use a spin-based amplifier [10,26] to constrain hypothetical axions within the axion window through searching for the exotic spin-spin interaction V pp between polarized electron and neutron spins. This spin sensor employs an ensemble of hyperpolarized long-lived 129 Xe nuclear spins as an amplifier for the pseudomagnetic fields from the exotic interactions, which are read out with an atomic magnetometer [23,37]. We demonstrate that the signal from pseudomagnetic fields is enhanced by a factor of more than 40.…”

“…Since the first experimental searches for exotic spin-spin interactions [2], recent progress on exploring such interactions over a broad range of particle masses has been enabled by advances in techniques including magnetometry [8,[21][22][23][24], nuclear magnetic resonance [10,20,25,26], torsionpendulum measurements [27,28], trapped ions measurements [29], nitrogen-vacancy centers in diamond [30], geoelectrons [31,32], neutron beams [9], masers [33,34] and cantilevers [35]. The tree-level interactions arising from pseudoscalar boson exchange are spin-dependent [36].…”

“…Both the source and the sensor are enclosed in fivelayer magnetic shield. The cell 1 [23,34,37] ventional magnetometer to detect the enhanced field. This technique takes advantage of the nuclear magnetic resonance between the modulated pseudomagnetic field B a and 129 Xe spins.…”

“…Both the source and the sensor are enclosed in fivelayer magnetic shield. The cell 1[23,34,37] containing 5 torr of isotopically enriched 129 Xe, 250 torr N 2 and a droplet of87 Rb is heated to 165 • C. The 87 Rb spins are polarized with a circularly polarized beam of 795 nm D1 light.129 Xe spins are polarized to ∼30% in spin-exchange collisions with polarized 87 Rb spins[10,40]. The x component of 87 Rb spins is measured via optical rotation of a linearly polarized probe beam, which is detuned to higher frequencies by 110 GHz from the D2 resonance.…”

Floquet Spin Amplification

“…1(a)], the polarized 129 Xe spins are tilted away from the ẑ direction and accordingly generate oscillating transverse magnetization M n (t). The Fermi-contact collisions between 129 Xe and 87 Rb lead to that 87 Rb experiences an effective magnetic field [30][31][32], B eff = (8πκ 0 /3)M n (t), which is in situ read out by 87 Rb magnetometer [33][34][35]. Here κ 0 ≈ 540 denotes the Fermi-contact enhancement factor between 129 Xe and 87 Rb [36].…”