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A Bloch point represents a three-dimensional hedgehog singularity of a magnetic vector field in which the magnetization vanishes. However, standard micromagnetic theory, developed for magnetic moments of fixed lengths, lacks full…

In this paper, we present a triaxial alignment magnetometer based on free-spin precession deployed in the geomagnetic range. Existing vector measurement methods often require complex optical setups, heating structures, and laser modulation.…

Atomic Physics · Physics 2025-02-18 Ge Jin , Tao Shi , Sheng Zou

We introduce a vector atomic magnetometer that employs a fast-rotating magnetic field applied to a pulsed $^{87}$Rb scalar atomic magnetometer. This approach enables simultaneous measurements of the total magnetic field and its two polar…

Quantum Physics · Physics 2025-02-07 Tao Wang , Wonjae Lee , Mark Limes , Tom Kornack , Elizabeth Foley , Michael Romalis

We report the development of new terahertz techniques for rapidly measuring the complex Faraday angle in systems with broken time-reversal symmetry using the cyclotron resonance of a GaAs two-dimensional electron gas in a magnetic field as…

Materials Science · Physics 2015-06-03 D. K. George , A. V. Stier , C. T. Ellis , B. D. McCombe , J. Černe , A. G. Markelz

We present an experimental and theoretical study of a scalar atomic magnetometer using an oscillating field-driven Zeeman resonance in a high-density optically-pumped potassium vapor. We describe an experimental implementation of an atomic…

Atomic and Molecular Clusters · Physics 2013-05-29 S. J. Smullin , I. M. Savukov , G. Vasilakis , R. K. Ghosh , M. V. Romalis

High-quality spatially-resolved measurements of electric fields are critical to understanding charge injection, charge transport, and charge trapping in semiconducting materials. Here, we report a variation of frequency-modulated Kelvin…

Mesoscale and Nanoscale Physics · Physics 2017-10-30 Ryan P. Dwyer , Louisa M. Smieska , Ali Moeed Tirmzi , John A. Marohn

In 1929 Felix Bloch suggested that the paramagnetic Fermi sea of electrons should make a spontaneous transition to a fully-magnetized state at very low densities, because the exchange energy gained by aligning the spins exceeds the…

The operation of polarimetric based single beam three axis atomic magnetometer is studied. The magnetometer operates in presence of small bias magnetic field. Its salient features are compared with the analysis of Bloch equation. The…

Atomic Physics · Physics 2019-03-18 Swarupananda Pradhan , Rita Behera

The dynamics of large spin-1/2 ensembles in the presence of a varying magnetic field are commonly described by the Bloch equation. Most magnetic field variations result in unintuitive spin dynamics, which are sensitive to small deviations…

We study the controllability of the Bloch equation, for an ensemble of non interacting half-spins, in a static magnetic field, with dispersion in the Larmor frequency. This system may be seen as a prototype for infinite dimensional bilinear…

Optimization and Control · Mathematics 2015-05-13 Karine Beauchard , Jean-Michel Coron , Pierre Rouchon

The three axis magnetic field measurement based on the interaction of a single elliptically polarized light beam with an atomic system is described. The magnetic field direction dependent atomic responses are extracted by the polarimetric…

Instrumentation and Detectors · Physics 2016-09-21 Swarupananda Pradhan

We introduce a methodology to calibrate in situ a set of coils generating bi- or tri-axial magnetic fields, at frequencies where a calibration performed under static conditions would be inaccurate. The methodology uses harmonic analysis of…

Instrumentation and Detectors · Physics 2025-07-08 Giuseppe Bevilacqua , Valerio Biancalana , Yordanka Dancheva , Alessandro Fregosi

Zero-field optically pumped magnetometers (OPMs) have emerged as an important technology for biomagnetism due to their ulta-sensitive performance, contained within a non-cryogenic small-scale sensor-head. The compactness of such OPMs is…

Feshbach association of ultracold molecules using narrow resonances requires exquisite control of the applied magnetic field. Here we present a magnetic field control system to deliver magnetic fields of over 1000 G with ppm-level precision…

This is the last paper in a series of three in which we have studied the Peierls substitution in the case of a weak magnetic field. Here we deal with two $2d$ Bloch eigenvalues which have a conical crossing. It turns out that in the…

Mathematical Physics · Physics 2021-06-02 Horia D. Cornean , Bernard Helffer , Radu Purice

We present a new approach to the problem of Bloch electrons in magnetic ( sometimes called Azbel-Hofstadter problem) field, by making explicit a natural relation between the group of magnetic translations and the quantum group…

Condensed Matter · Physics 2009-10-22 P. B Wiegmann , A. V. Zabrodin

We propose a new method to compute magnetic surfaces that are parametrized in Boozer coordinates for vacuum magnetic fields. We also propose a measure for quasi-symmetry on the computed surfaces and use it to design coils that generate a…

Plasma Physics · Physics 2022-08-17 Andrew Giuliani , Florian Wechsung , Matt Landreman , Georg Stadler , Antoine Cerfon

A fast and simple frequency domain method is introduced for the analysis of microring modulator response using the Jacobi Anger expansion method. Resonance frequency modulated microring (FMMR) modulators and coupling modulated microring…

Signal Processing · Electrical Eng. & Systems 2017-10-03 Payam Rabiei

SERF magnetometers based on dense ensembles of alkali-metal spins are precision quantum sensors that hold the record of measured and projected sensitivity to magnetic fields, in the $\mu\textrm{G}-\textrm{mG}$ range. At geomagnetic fields…

Quantum Physics · Physics 2025-05-29 Mark Dikopoltsev , Uriel Levy , Or Katz

We develop and demonstrate a new protocol that allows sensing of magnetic fields in an extra-ordinary regime for atomic magnetometry. Until now, the demonstrated bandwidth for atomic magnetometry has been constrained to be slower than the…

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