arXiv subjects

A. O. Sushkov

Publications and source records attributed to A. O. Sushkov.

30 records · Page 2Linked to original sources

arXiv2009

Measurement of the short-range attractive force between Ge plates using a torsion balance

We have measured the short-range attractive force between crystalline Ge plates, and found contributions from both the Casimir force and an electrical force possibly generated by surface patch potentials. Using a model of surface patch effects that generates an additional force due to a distance dependence of the apparent contact potential, the electrical force was parameterized using data at distances where the Casimir force is relatively small. Extrapolating this model, to provide a correction to the measured force at distances less than 5 $μ$m, shows a residual force that is in agreement, within experimental uncertainty, with five models that have been used to calculate the Casimir force.

quant-ph↗

arXiv2008

The prospects for a new search for the electron electric dipole moment in solid Gadolinium iron garnet ceramics

We address a number of issues regarding solid state electron electric dipole moment (EDM) experiments, focusing on gadolinium iron garnet (abbreviated GdIG, chemical formula Gd$_3$Fe$_5$O$_{12}$) as a possible sample material. GdIG maintains its high magnetic susceptibility down to 4.2 K, which enhances the EDM-induced magnetization of a sample placed in an electric field. We estimate that lattice polarizability gives rise to an EDM enhancement factor of approximately 20. We also calculate the effect of the demagnetizing field for various sample geometries and permeabilities. Measurements of intrinsic GdIG magnetization noise are presented, and the fluctuation-dissipation theorem is used to compare our data with the measurements of the imaginary part of GdIG permeability at 4.2 K, showing good agreement above frequencies of a few hertz. We also observe how the demagnetizing field suppresses the noise-induced magnetic flux, confirming our calculations. The statistical sensitivity of an EDM search based on a solid GdIG sample is estimated to be on the same level as the present experimental limit. Such a measurement would be valuable, given the completely different methods and systematics involved. The most significant systematics in such an experiment are the magnetic hysteresis and the magneto-electric effect. Our analysis shows that it should be possible to control these at the level of statistical sensitivity.

physics.atom-ph↗

arXiv2008

Magnetic susceptibility and magnetization fluctuation measurements of mixed Gadolinium-Yttrium Iron Garnets

We study the magnetic properties of Gadolinium-Yttrium Iron Garnet ($\text{Gd}_{x}\text{Y}_{3-x}\text{Fe}_5\text{0}_{12}$, $x=3,1.8$) ferrite ceramics. The complex initial permeability is measured in the temperature range 2 K to 295 K at frequency of 1 kHz, and in the frequency range 100 Hz to 200 MHz at temperatures 4 K, 77 K, and 295 K. The magnetic viscosity-induced imaginary part of the permeability is observed at low frequencies. Measurements of the magnetization noise are made at 4 K. Using the fluctuation-dissipation theorem, we find that the observed magnetization fluctuations are consistent with our measurements of the low-frequency imaginary part of permeability. We discuss some implications for proposed precision measurements as well as other possible applications.

cond-mat.mtrl-sci↗

arXiv2008

Production of long-lived atomic vapor inside high-density buffer gas

Atomic vapor of four different paramagnetic species: gold, silver, lithium, and rubidium, is produced and studied inside several buffer gases: helium, nitrogen, neon, and argon. The paramagnetic atoms are injected into the buffer gas using laser ablation. Wires with diameters 25 $μ$m, 50 $μ$m, and 100 $μ$m are used as ablation targets for gold and silver, bulk targets are used for lithium and rubidium. The buffer gas cools and confines the ablated atoms, slowing down their transport to the cell walls. Buffer gas temperatures between 20 K and 295 K, and densities between $10^{16}$ cm$^{-3}$ and $2\times10^{19}$ cm$^{-3}$ are explored. Peak paramagnetic atom densities of $10^{11}$ cm$^{-3}$ are routinely achieved. The longest observed paramagnetic vapor density decay times are 110 ms for silver at 20 K and 4 ms for lithium at 32 K. The candidates for the principal paramagnetic-atom loss mechanism are impurities in the buffer gas, dimer formation and atom loss on sputtered clusters.

physics.atom-ph↗

arXiv2007

Nuclear-spin relaxation of $^{207}$Pb in ferroelectric powders

Motivated by a recent proposal by O. P. Sushkov and co-workers to search for a P,T-violating Schiff moment of the $^{207}$Pb nucleus in a ferroelectric solid, we have carried out a high-field nuclear magnetic resonance study of the longitudinal and transverse spin relaxation of the lead nuclei from room temperature down to 10 K for powder samples of lead titanate (PT), lead zirconium titanate (PZT), and a PT monocrystal. For all powder samples and independently of temperature, transverse relaxation times were found to be $T_2\approx 1.5 $ms, while the longitudinal relaxation times exhibited a temperature dependence, with $T_1$ of over an hour at the lowest temperatures, decreasing to $T_1\approx 7 $s at room temperature. At high temperatures, the observed behavior is consistent with a two-phonon Raman process, while in the low temperature limit, the relaxation appears to be dominated by a single-phonon (direct) process involving magnetic impurities. This is the first study of temperature-dependent nuclear-spin relaxation in PT and PZT ferroelectrics at such low temperatures. We discuss the implications of the results for the Schiff-moment search.

cond-mat.other↗

arXiv2006

Rubidium "whiskers" in a vapor cell

Crystals of metallic rubidium are observed ``growing'' from paraffin coating of buffer-gas-free glass vapor cells. The crystals have uniform square cross-section, $\approx 30 μ$m on the side, and reach several mm in length.

physics.atom-ph↗

arXiv2005

On the sensitivity of condensed-matter P- and T-violation experiments

Experiments searching for parity- and time-reversal-invariance-violating effects that rely on measuring magnetization of a condensed-matter sample induced by application of an electric field are considered. A limit on statistical sensitivity arises due to random fluctuations of the spins in the sample. The scaling of this limit with the number of spins and their relaxation time is derived. Application to an experiment searching for nuclear Schiff moment in a ferroelectric is discussed.

cond-mat.other↗

arXiv2005

Nonlinear Magneto-Optical Rotation with Amplitude-Modulated Light: AMOR

A new technique of nonlinear magneto-optical rotation with amplitude modulated light is developed. The technique is an alternative to its counterpart with frequency modulated light and can be applied to sensitive measurements of magnetic fields ranging from microgauss to the Earth-field level. The rotation signals exhibit nontrivial features like narrowed non-Lorentzian lineshapes and multi-component resonances.

physics.optics↗

arXiv2005

On the transmission of light through tilted interference filters

The transmission characteristics of commercial interference filters are not quite what we expected from the specifications provided by manufacturers. The unexpectedly sharp dependences of the transmission coefficient on the incidence angle, wavelength, and on the position where the light beam falls on the filter may be important in the analysis of systematic effects in experiments incorporating interference filters.

physics.optics↗

arXiv2004

AC Stark shift noise in QND measurement arising from quantum fluctuations of light polarization

In a recent letter [Auzinsh {\it{et. al.}} (physics/0403097)] we have analyzed the noise properties of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum nondemolition measurement. Such a magnetometer measures spin precession of $N$ atomic spins by detecting optical rotation of far-detuned probe light. Here we consider maximally squeezed probe light, and carry out a detailed derivation of the contribution to the noise in a magnetometric measurement due to the differential AC Stark shift between Zeeman sublevels arising from quantum fluctuations of the probe polarization.

physics.atom-ph↗

arXiv2004

Can a quantum nondemolition measurement improve the sensitivity of an atomic magnetometer?

Noise properties of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum nondemolition measurement are considered. Such a magnetometer measures spin precession of $N$ atomic spins by detecting optical rotation of far-detuned light. Fundamental noise sources include the quantum projection noise and the photon shot-noise. For measurement times much shorter than the spin-relaxation time observed in the absence of light ($τ_{\rm rel}$) divided by $\sqrt{N}$, the optimal sensitivity of the magnetometer scales as $N^{-3/4}$, so an advantage over the usual sensitivity scaling as $N^{-1/2}$ can be achieved. However, at longer measurement times, the optimized sensitivity scales as $N^{-1/2}$, as for a usual shot-noise limited magnetometer. If strongly squeezed probe light is used, the Heisenberg uncertainty limit may, in principle, be reached for very short measurement times. However, if the measurement time exceeds $τ_{\rm rel}/N$, the $N^{-1/2}$ scaling is again restored.

physics.atom-ph↗

arXiv2004

Kerr effect in liquid helium at temperatures below the superfluid transition

The electro-optical Kerr effect induced by a slowly-varying applied electric field in liquid helium at temperatures below the $λ$-point is investigated. The Kerr constant of liquid helium is measured to be $(1.43\pm 0.02^{(stat)} \pm 0.04^{(sys)})\times 10^{-20}$ (cm/V)$^2$ at $T=1.5$ K. Within the experimental uncertainty, the Kerr constant is independent of temperature in the range $T=1.5$ K to 2.17 K, which implies that the Kerr constant of the superfluid component of liquid helium is the same as that of normal liquid helium. Our result also indicates that pair and higher correlations of He atoms in the liquid phase account for about 23% of the measured Kerr constant. Liquid nitrogen was used to test the experimental set-up, the result for the liquid nitrogen Kerr constant is $(4.38\pm 0.15)\times 10^{-18} $(cm/V)$^2$. The knowledge of the Kerr constant in these media allows the Kerr effect to be used as a non-contact technique for measuring the magnitude and mapping out the distribution of electric fields inside these cryogenic insulants.

physics.optics↗