Spin-exchange collisions often play a dominant role in the broadening of Zeeman resonances in an alkali-metal vapor. Contrary to intuitive expectations, at high alkali-metal densities this broadening ...can be completely eliminated by operating in a low magnetic field, allowing construction of ultrasensitive atomic magnetometers. We describe a detailed study of the Zeeman resonance frequencies and linewidths as a function of the magnetic field, alkali-metal density, and the degree of spin polarization of the atoms. Due to the nonlinear nature of the density matrix equations describing the spin-exchange collisions both the gyromagnetic ratio and the linewidth change as a function of the polarization. The results of experimental measurements are in excellent agreement with analytical and numerical solutions of the density matrix equations.
In this work, we have found that the key to minimizing the effect of the end-cap openings in multishell shields lies with widening the axial air-gaps between the end-caps. We have revealed that the ...axial air-gaps strongly influence the shielding with openings, while practically not affecting-if the gaps are not too narrow, of course-the shielding with no openings. As a result, widening the axial air-gaps can bring the axial shielding with large openings very close to that with no openings at all. To investigate as general case as possible we have described with the help of special charts the five-shell shields with typical 1.25, 1.5, and 1.75 aspect ratios for the innermost shell. The charts showed that while the shielding with no openings increases monotonically with either shortening the innermost shell or increasing the radial air-gaps, the shielding with openings reaches an extreme, which depends on the normalized permeability. Another important finding is that in contrast to small openings, the effect of large openings depends strongly on the radial air-gaps. Using the charts developed, a typical five-shell shield can be easily optimized in order to compensate for the effect of the openings and match the performance of the corresponding closed shield.
Measurement of linear stark interference in 199Hg Loftus, T H; Swallows, M D; Griffith, W C ...
Physical review letters,
2011-Jun-24, 20110624, 2011-06-24, Letnik:
106, Številka:
25
Journal Article
Recenzirano
We present measurements of Stark interference in the (61)S(0)→6(3)P(1) transition in (199)Hg, a process whereby a static electric field E mixes magnetic dipole and electric quadrupole couplings into ...an electric dipole transition, leading to E-linear energy shifts similar to those produced by a permanent atomic electric dipole moment (EDM). The measured interference amplitude, a(SI) = (a(M1) + a(E2)) = (5.8 ± 1.5) × 10(-9) (kV / cm)(-1), agrees with relativistic, many-body predictions and confirms that earlier central-field estimates are a factor of 10 too large. More importantly, this study validates the capability of the (199)Hg EDM search apparatus to resolve nontrivial, controlled, and sub-nHz Larmor frequency shifts with EDM-like characteristics.
We present a next-to-leading order perturbative QCD analysis of world data on the spin dependent structure functions
g
1
p
,
g
1
n
, and
g
1
d
, including the new experimental information on the
Q
2 ...dependence of
g
1
n
. Careful attention is paid to the experimental and theoretical uncertainties. The data constrain the first moments of the polarized valence quark distributions, but only qualitatively constrain the polarized sea quark and gluon distributions. The NLO results are used to determine the
Q
2 dependence of the ratio
g
1
F
1
and evolve the experimental data to a constant
Q
2 = 5 GeV
2. We determine the first moments of the polarized structure functions of the proton and neutron and find agreement with the Bjorken sum rule.
We describe a ^{3}He-^{129}Xe comagnetometer using ^{87}Rb atoms for noble-gas spin polarization and detection. We use a train of ^{87}Rb π pulses and σ^{+}/σ^{-} optical pumping to realize a ...finite-field Rb magnetometer with suppression of spin-exchange relaxation. We suppress frequency shifts from polarized Rb by measuring the ^{3}He and ^{129}Xe spin precession frequencies in the dark, while applying π pulses along two directions to depolarize Rb atoms. The plane of the π pulses is rotated to suppress the Bloch-Siegert shifts for the nuclear spins. We measure the ratio of ^{3}He to ^{129}Xe spin precession frequencies with sufficient absolute accuracy to resolve Earth's rotation without changing the orientation of the comagnetometer. A frequency resolution of 7 nHz is achieved after integration for 8 h without evidence of significant drift.
Paramagnetic Faraday rotation is a powerful technique for atom sensing widely used in quantum nondemolition measurements, fundamental symmetry tests, and other precision measurements. We demonstrate ...the use of a multipass optical cell for Faraday rotation spectroscopy and observe polarization rotation in excess of 100 rad from spin-polarized Rb vapor. Unlike optical cavities, multipass cells have a deterministic number of light passes and can be used to measure large optical rotations. We also observe a tenfold suppression of transverse spin relaxation when Rb atoms are placed in a coherent superposition state immune to spin-exchange collisions.
We discuss the use of comagnetometry in studying new physics that couples to fermionic spin. Modern comagnetometry is -- in absolute energy units -- the most sensitive experimental technique for ...measuring the energy difference between quantum states, reaching sensitivities in the \(10^{-26}\,\)eV range. The technique suppresses the magnetic interactions of the spins, making searches for non-standard-model interactions possible. Many implementations have been developed and optimized for various uses. New physics scenarios which can be probed with comagnetometers include: EDMs, violations of Lorentz invariance, Goldstone bosons of new high-energy symmetries, CP-violating long-range forces, and axionic dark matter. We consider the prospects for improvements in the technique, and show -- based purely on signal-to-noise ratio with existing technology -- that there is room for several orders of magnitude in further improvement. We also evaluate several sources of systematic error and instability that may limit improvements.
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