Probing magnetic field effects in 12-pole linear ion trap frequency standards
The second-order Zeeman shift in a 12-pole buffer-gas-cooled linear ion trap frequency standard is characterized.
linear ion trap frequency standard 12-pole trap Ze↗
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Zeeman observations of W Sgr
A new precise method for measuring magnetic fields on Zeeman plates of the southern Cepheid 'W Sgr' is reviewed. Ten plates over the 7.6(d) period of pulsation show two extrema in the measured values of the effective magnetic field. The method has a precision of + or - 0.4 microns in the Zeeman shift corresponding to + or - 50 Gauss (g). A negative spike of -220 g occurred at the time of arrival of the compressional wave of pulsation at the stellar surface. A positive field of +270 g occurred at the phase of most rapid contraction near the temperature minimum of the pulsation cycle.
Wood, H. J.↗
Spin Qubits in Germanium Structures with Phononic Gap
We propose qubits based on shallow donor electron spins in germanium structures with phononic gap. We consider a phononic crystal formed by periodic holes in Ge plate or a rigid cover / Ge layer / rigid substrate structure with gaps approximately a few GHz. The spin relaxation is suppressed dramatically, if the Zeeman frequency omegaZ is in the phononic gap, but an effective coupling between the spins of remote donors via exchange of virtual phonons remains essential. If omegaZ approaches to a gap edge in these structures, a long-range (limited by detuning of omegaZ) resonant exchange interaction takes place. We estimate that ratio of the exchange integral to the longitudinal relaxation rate exceeds 10(exp 5) and lateral scale of resonant exchange 0.1 mm. The exchange contribution can be verified under microwave pumping through oscillations of spin echo signal or through the differential absorption measurements. Efficient manipulation of spins due to the Rabi oscillations opens a new way for quantum information applications.
Qubit↗
Anomalous conductivity due to relativistic Landau quantization
Here we use a recently developed kinetic model derived from the Dirac equation, in order to study electromagnetic wave propagation in superstrong magnetic fields, such as in magnetars, where relativistic Landau quantization is prominent. The leading contribution to the conductivity tensor in such a plasma is calculated. It is found that the electron Hall current has an anomalous contribution, in the quantum relativistic regime, where the effective particle energy has a significant contribution from the diamagnetic and Zeeman energy. As a result, a new quantum resonance frequency appears, and the dispersion relation for the left- and right-hand polarized modes are strongly modified for long and moderate wavelengths. The implications for magnetar physics are discussed.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Solar magnetic fields measurements with a magneto-optical filter
The presence of a magnetic field at different levels inside the sun has crucial implications for helioseismology. The solar oscillation observing program carried out since 1983 at Mt. Wilson with Cacciani magneto-optical filter has recently been modified to acquire full-disk magnetograms with 2 arcsec spatial resolution. A method for the correct determination of magnetic maps which are free of contamination by velocity signal is presented. It is shown that no cross-talk exists between the Doppler and Zeeman shifts of the Na D lines, provided that instrumental polarization effects are taken into account. The observed line-of-sight photospheric field was used to map the vector field in the inner corona, above active regions, in the current free approximation.
Cacciani, A.↗
Spectra of circularly polarized radiation from astrophysical OH masers
A striking feature of astrophysical masers is the tendency for either one or the other of the circular polarizations to dominate in the radiation from the strong, widely observed masing transitions of OH at 18 cm. Spectral line profiles are calculated for polarized maser radiation due to the combined effects of a velocity gradient and, as is indicated for these transitions, a Zeeman splitting that is at least comparable with the thermal contributions to the breadths of the spectral lines. The resulting spectral features are similar in appearance, including the presence of large net circular polarization and narrow line breadths, to the commonly observed spectra of OH masers in molecular clouds. The calculations presented here are performed as a function of frequency without making the approximations of a large velocity gradient. Rapid cross relaxation, which has been advocated by others for the OH masers, is assumed.
Nedoluha, Gerald E.↗
Refined Sensitivity Estimates for Single-Molecule Magnet Dark Matter Detectors
We revisit the sensitivity of Single Molecule Magnet (SMM) crystals as detectors for low-mass dark matter. In previous work, we established the concept of the ``magnetic bubble chamber'', where energy deposited by dark matter triggers a magnetic avalanche in a metastable crystal. The original sensitivity estimates relied on a conservative criterion requiring the spin relaxation time to be strictly shorter than the thermal diffusion time. Here, we demonstrate that this criterion effectively ignores the stochastic nature of spin relaxation. We derive a refined analytic estimate which accounts for the fraction of spins that relax even when diffusion is fast. We show that the Zeeman energy released by this fraction contributes to local heating, significantly lowering the energy threshold for avalanche formation. We present simulation results confirming this effect and report on experimental verification of the assumed low-temperature thermal properties of two representative SMM crystals, Mn$_{12}$-acetate and Mn$_{32}$. Together, these efforts extend this pathfinder program toward the realization of SMM-based detectors with controlled material properties and enhanced dark matter sensitivity.
Eberhardt, Andrew [Tokyo U., IPMU]↗
[Probing Planck-scale Physics with a Ne-21/He-3 Zeeman Maser]
The Ne-21/He-3 Zeeman maser is a recently developed device which employs co-located ensembles of Ne-21 and He-3 atoms to provide sensitive differential measurements of the noble gas nuclear Zeeman splittings as a function of time, thereby greatly attenuating common-mode systematic effects such as uniform magnetic field variations. The Ne-21 maser will serve as a precision magnetometer to stabilize the system's static magnetic field, while the He-3 maser is used as a sensitive probe for violations of CPT and Lorentz symmetry by searching for small variations in the 3He maser frequency as the spatial orientation of the apparatus changes due to the rotation of the Earth (or placement on a rotating table). In the context of a general extension of the Standard Model of particle physics, the Ne-21/He-3 maser will provide the most sensitive search to date for CPT and Lorentz violation of the neutron: better than 10(exp -32) GeV, an improvement of more than an order of magnitude over past experiments. This exceptional precision will offer a rare opportunity to probe physics at the Planck scale. A future space-based Ne-21/He-3 maser or related device could provide even greater sensitivity to violations of CPT and Lorentz symmetry, and hence to Planck-scale physics, because of isolation from dominant systematic effects associated with ground-based operation, and because of access to different positions in space-time.
Source record↗
Heat conduction in magnetic insulators via hybridization of acoustic phonons and spin-flip excitations
We present a comprehensive study on the longitudinal magnetothermal transport in a paramagnetic effective spin-1/2 magnetic insulator CsYbSe 2 , by introducing a minimal model requiring only Zeeman splitting and magnetoelastic coupling. We use it to argue that hybridized excitations—formed from acoustic phonons and localized spin-flip-excitations across the Zeeman gap of the crystal electric field ground doublet—are responsible for a nonmonotonic field dependence of longitudinal thermal conductivity. Beyond highlighting a starring role for phonons, our results raise the prospect of universal magnetothermal transport phenomena in paramagnetic insulators that originate from simple features shared across many systems. Published by the American Physical Society 2025
Pocs, Christopher A.↗
A Measurement of Atmospheric Circular Polarization with POLARBEAR
At millimeter wavelengths, the atmospheric emission is circularly polarized owing to the Zeeman splitting of molecular oxygen by the Earth's magnetic field. We report a measurement of the signal in the 150 GHz band using 3 yr of observational data with the POLARBEAR project. Nonidealities of a continuously rotating half-wave plate (HWP) partially convert circularly polarized light to linearly polarized light. While POLARBEAR detectors are sensitive to linear polarization, this effect makes them sensitive to circular polarization. Although this was not the intended use, we utilized this conversion to measure circular polarization. We reconstruct the azimuthal gradient of the circular polarization signal and measure its dependency from the scanning direction and the detector bandpass. We compare the signal with a simulation based on atmospheric emission theory, the detector bandpass, and the HWP leakage spectrum model. We find the ratio of the observed azimuthal slope to the simulated slope is 0.92 ± 0.01(stat) ± 0.07(sys). This ratio corresponds to a brightness temperature of 3.8 mK at the effective band center of 121.8 GHz and bandwidth of 3.5 GHz estimated from representative detector bandpass and the spectrum of Zeeman emission. This result validates our understanding of the instrument and reinforces the feasibility of measuring the circular polarization using the imperfection of continuously rotating HWP. Continuously rotating HWP is popular in ongoing and future cosmic microwave background experiments to modulate the polarized signal. This work shows a method for signal extraction and leakage subtraction that can help measure circular polarization in such experiments.
79 ASTRONOMY AND ASTROPHYSICS↗
Bound on Lorentz and CPT Violating Boost Effects for the Neutron
A search for a sidereal annual variation in the frequency difference between co-located Xe-129 and He-3 Zeeman masers sets a limit of approximately 10(exp -27) GeV on the coupling of the neutron to the time component of a possible background Lorentz and CPT violating tensor field.
Walsworth, Ronald↗
Interpretation of vector magnetograph data including magneto-optic effects. I - Azimuth angle of the transverse field
In this paper, the presence of Faraday rotation in measurements of the orientation of a sunspot's transverse magnetic field is investigated. Using observations obtained with the Marshall Space Flight Center's (MSFC) vector magnetograph, the derived vector magnetic field of a simple, symmetric sunspot is used to calculate the degree of Faraday rotation in the azimuth of the transverse field as a function of wavelength from analytical expressions for the Stokes parameters. These results are then compared with the observed rotation of the field's azimuth which is derived from observations at different wavelengths within the Fe I 5250 A spectral line. From these comparisons, it is found: the observed rotation of the azimuth is simulated to a reasonable degree by the theoretical formulations if the line-formation parameter is varied over the sunspot; these variations are substantiated by the line-intensity data; for the MSFC system, Faraday rotation can be neglected for field strengths less than 1800 G and field inclinations greater than 45 deg; to minimize the effects of Faraday rotation in sunspot umbrae, MSFC magnetograph measurements must be made in the far wings of the Zeeman-sensitive spectral line.
West, E. A.↗
Superconducting diode effect in two-dimensional topological insulator edges and Josephson junctions
The superconducting diode effect—the dependence of critical current on its direction—can arise from the simultaneous breaking of inversion and time-reversal symmetry in a superconductor and has gained interest for its potential applications in superconducting electronics. In this Letter, we study the effect in a two-dimensional topological insulator (2D TI) in both a uniform geometry as well as in a long Josephson junction. We show that in the presence of Zeeman fields, a circulating edge current enables a large non-reciprocity of the critical current. We find a maximum diode efficiency of 1 for the uniform 2D TI and (2−1)2≈0.17 for the long Josephson junction.
Physics↗
New measurements of photospheric magnetic fields in late-type stars and emerging trends
The magnetic fields of late-type stars are measured using the method of Saar et al. (1986). The method includes radiative transfer effects and compensation for line blending; the photospheric magnetic field parameters are derived by comparing observed and theoretical line profiles using an LTE code that includes line saturation and full Zeeman pattern. The preliminary mean active region magnetic field strengths (B) and surface area coverages for 20 stars are discussed. It is observed that there is a trend of increasing B towards the cooler dwarfs stars, and the linear correlation between B and the equipartition value of the magnetic field strength suggests that the photospheric gas pressure determines the photospheric magnetic field strengths. A tendency toward larger filling factors at larger stellar angular velocities is also detected.
Saar, S. H.↗
Broad-band polarization in molecular spectra
The rotational lines of the CN(0,0) red system have been observed to show a strongly asymmetric Zeeman profile. Certain molecules are very susceptible to magnetic perturbation because of the weakness of their spin-rotation coupling; a fairly weak magnetic field can cause a complete Paschen-Back effect. The calculation of transition probabilities incorporating this effect into the Hamiltonian is discussed, and the detailed calculation is then given. The resulting transition probabilities are transformed into synthetic line profiles by using the Unno (1956) model of polarized radiation transfer. The dependence of the net polarized flux on magnetic field and equivalent width is investigated. It is shown that entire band systems may be significantly polarized. Broad-band circular polarization of sunspots may be due, in part, to molecular bands. Analysis of the CH G band indicates a magnetic field of 0.25-0.50 x 10 to the 6th gauss in the white dwarf G99-37, an order of magnitude lower than previous estimates.
Illing, R. M. E.↗
Hg-201 (+) CO-Magnetometer for HG-199(+) Trapped Ion Space Atomic Clocks
Local magnetic field strength in a trapped ion atomic clock is measured in real time, with high accuracy and without degrading clock performance, and the measurement is used to compensate for ambient magnetic field perturbations. First and second isotopes of an element are co-located within the linear ion trap. The first isotope has a resonant microwave transition between two hyperfine energy states, and the second isotope has a resonant Zeeman transition. Optical sources emit ultraviolet light that optically pump both isotopes. A microwave radiation source simultaneously emits microwave fields resonant with the first isotope's clock transition and the second isotope's Zeeman transition, and an optical detector measures the fluorescence from optically pumping both isotopes. The second isotope's Zeeman transition provides the measure of magnetic field strength, and the measurement is used to compensate the first isotope's clock transition or to adjust the applied C-field to reduce the effects of ambient magnetic field perturbations.
Burt, Eric A.↗
The polarization properties of Fe II 614.9 nm
The anomalous Zeeman splitting of the Fe II line at 614.9 nm results in four unusual properties of the polarization signature of this line in the presence of magnetic fields: the absence of linear polarization, no magnetooptical effect, the independence of intensity at line center from the inclination of the field, and a depolarizing self-absorption. The origin of these properties is illustrated in terms of the transfer of line radiation in an idealized solar atmosphere.
Lites, Bruce W.↗
Measurements of solar magnetic fields by Fourier transform techniques. II - Saturated and blended lines
Fourier techniques have been exhaustively calibrated using Unno's (1956) results for the absorption profile of a simple Zeeman triplet. If a simple transformation is applied to the normalized line depths, then magnetic-field strengths and inclination angles can be measured very accurately from noisy saturated line profiles. Systematic errors caused by saturation effects can be estimated and reduced by varying one parameter. When a significant fraction of the line profile is unsplit and unpolarized, large errors may be made in measurements of low fields, unless the line is sufficiently weak. For a weak line, a vertical field of 1600 gauss can be measured to 10% accuracy even when 70% of the line profile is stray light. These stray-light errors are troublesome in measuring fields of gaps and pores but not sunspots. Numerical results of the error analysis are presented graphically.
Tarbell, T. D.↗