We have measured the resistive and reactive mutual friction coefficients $B$ ${B}^{\ensuremath{'}}$ in rotating superfluid $^{3}\mathrm{He}$-$B$ at pressures of 1.6, 10, 20, 29.3 bars. Near ${T}_{c}$, $\frac{B{\ensuremath{\rho}}_{n}}{\ensuremath{\rho}}$ diverges as ${({T}_{c}\ensuremath{-}T)}^{a}$, with $a\ensuremath{\approx}\ensuremath{-}0.7$, $\frac{{B}^{\ensuremath{'}}{\ensuremath{\rho}}_{n}}{\ensuremath{\rho}}\ensuremath{-}2$ tends to zero. Coefficients ${d}_{\ensuremath{\parallel}}$...

Vortices in $^{3}\mathit{A}$ low magnetic fields (H\ensuremath{\le}20 mT) have been studied by ultrasonics. A first-order phase change between two vortex types, with dissimilar sound absorption, has found. The field at the transition is on order of dipolar ${\mathit{H}}_{\mathit{d}}$. observed occurs continuous textures different topological charges d^ (where anisotropy vector).

The shape of the free surface rotating superfluid $^{3}\mathit{B}$ has been investigated optically. drastic change in viscosity at transition was seen directly. Focusing light reflected from liquid and expansion beam when it travels through $^{3}\mathrm{He}$ sample show that meniscus same parabolic as normal liquid, which implies an equilibrium density vortices. fountain effect could be directly well: Liquid accumulates into illuminated region.

We have performed experiments where hot electrons are extracted from a normal metal into superconductor through tunnel junction. measured the cooling performance of such NIS junctions, especially in cases another electrode, quasiparticle trap, is attached to at different distances junction direct metal–to–metal contact or an oxide barrier. The submicron distance allows superior thermalization superconductor. analyzed theoretically heat transport this system. From both experiment and theory,...

Zero sound attenuation at 8.9 and 26.8 MHz in $^{3}\mathit{B}$ shows an extremum ${\mathrm{T}}_{\mathrm{AB}}$ a field of \ensuremath{\sim}2 kG low pressures, both the stationary rotating superfluid. This is accordance with prediction that critical magnetic separates two types B phases AB transition line, without nodes energy gap, respectively, change nature transition. The phase takes place via intermediate state, possibly new phase, characterized by excess attenuation.

A silicon electron pump operating at the temperature of liquid helium has demonstrated repeatable operation with sub-ppm accuracy. The current, approximately 168 pA, is measured by three laboratories, and measurements agree expected current ef within uncertainties which range from 0.2 ppm to 1.3 ppm. All are carried out in zero applied magnetic field, drive signal a sine wave. combination simple conditions high accuracy demonstrates possibility that an can operate as standard National...

We have measured the resistive and reactive mutual friction coefficients in rotating superfluid ${}^{3}\mathrm{H}\mathrm{e}\ensuremath{-}A$ at $29.3\mathrm{bars}$ pressure. The results agree with those predicted from equation of orbital hydrodynamics for two quantum continuous vortices if previously value viscosity is used. Our put an upper limit on inertia less than $0.005\ensuremath{\Elzxh}$ per Cooper pair. explain our observation history-dependent textures by noting that ease formation...

We have observed in superfluid $^{3}\mathit{B}$ two-phonon absorption, which is one of the nonlinear effects recently predicted by McKenzie and Sauls. The J=${2}^{+}$ real squashing mode was excited with two coincident sound pulses at temperature ${\mathit{T}}^{+}$, ${\mathrm{f}}_{\mathrm{signal}}$+${\mathit{f}}_{\mathrm{pump}}$=${\mathit{f}}_{\mathrm{rsq}}$(${\mathit{T}}^{+}$), under 0, 2.7, 3.5 bars pressure. heights attenuation peaks scale almost linearly energy higher-intensity wave,...

Zero sound experiments on superfluid 3He-A at low pressures (< 3 bar) and in strong magnetic fields (> 0.3 T) show an increase the attenuation temperatures (⩽ 0.4 mK) which has been a puzzle until present experiment. Coupling of re-entrant normal flapping (NFL) mode to zero geometry where propagates direction field is shown arise from boundary layer walls whose thickness about dipolar coherence length ξD 3He-A. We estimate value intermediate pressures. have also studied nonlinearity...

We have made simultaneous measurements of the longitudinal and transverse NMR frequencies $^{3}\mathit{A}$ in fields order 30 G a parallel plate geometry, defined by Mylar films 100 \ensuremath{\mu}m apart, so that l\ifmmode \hat{}\else \^{}\fi{} is well oriented perpendicular to static magnetic field. Comparison our with quadratic axial-state frequency relation indicates A phase axial pressure range 22.6 29.3 bars.

Parametric excitation yields new results, which cannot be obtained by conventional linear spectroscopy, on the collective modes in superfluid $^{3}\mathit{B}$. In our ultrasonic experiments, performed a chamber with four quartz crystals, we have excited real squashing (J=${2}^{+}$) two simultaneous sound waves are mutually either parallel, orthogonal, or antiparallel. Qualitatively these results agreement theoretical dispersion relation of J=${2}^{+}$ modes, and quantitatively been able to...

Cooling of electrons in a heavily doped silicon by quasiparticle tunneling using superconductor–semiconductor–superconductor double-Schottky-junction structure is demonstrated at low temperatures. In this work, we use Al as the superconductor and thin silicon-on-insulator (SOI) film semiconductor. The electron–phonon coupling measured for SOI value shown to be origin observed significant cooling effect.

Series connection of four quantum Hall effect (QHE) devices based on epitaxial graphene films was studied for realization a resistance standard with an up-scaled value. The tested showed plateaux RH,2 at filling factor i = 2 starting from relatively low magnetic field (between 4 T and 5 T) when temperature 1.5 K. Precision measurements quantized QHE connected by triple series connections external bonding wires were done B 7 K using commercial precision bridge 50 microA current through the...

Electrothermal elements are used in various energy harvesters, coolers, and radiation detectors. The optimal operation of these relies on mastering two competing boundary conditions: the maximization electrothermal response blockade lattice (phonon) thermal conduction. In this work, we propose demonstrate that efficient phonon blocking can be achieved solid-state thermionic junctions, paving way for new phonon-engineered high-efficiency refrigerators sensors. Our experimental demonstration...

We have applied tunneling of electrons between a normal metal and superconductor to refrigerate thin dielectric membrane attached the electrode superconductor/ insulator/normal-metal/insulator/superconductor (SINIS) structure. Starting from T≈200 mK, decrease in temperature several mK was observed, measured by separate thermometer on membrane. It should be straightforward improve refrigerator performance level recently demonstrated SINIS electron cooling method, such that drop lattice would...

Coulomb blockade thermometry (CBT) provides a simple method for absolute in every day laboratory use at cryogenic temperatures. CBT has been found insensitive to even high magnetic fields. We review the principles and operation of fabrication sensors, present new data on radiation hardness stability sensors. describe instrumentation detail. have developed two signal conditioning units measurements. One is modified alternating current resistance bridge, versatile instrument operating with PC...

The hold time $\tau$ of a single-electron trap is shown to increase significantly due suppression environmentally assisted tunneling events. Using two rf-tight radiation shields instead single one, we demonstrate by factor exceeding $10^3$, up about 10 hours, for with only superconductor (S) -- normal-metal (N) tunnel junctions and an on-chip resistor $R$ (R-SNS structure). In the normal state, improved shielding made it possible observe $\tau\sim$ 100 s, which in reasonable agreement...