1,425 research outputs found
Advanced Concepts in Josephson Junction Reflection Amplifiers
Low-noise amplification atmicrowave frequencies has become increasingly
important for the research related to superconducting qubits and
nanoelectromechanical systems. The fundamental limit of added noise by a
phase-preserving amplifier is the standard quantum limit, often expressed as
noise temperature . Towards the goal of the
quantum limit, we have developed an amplifier based on intrinsic negative
resistance of a selectively damped Josephson junction. Here we present
measurement results on previously proposed wide-band microwave amplification
and discuss the challenges for improvements on the existing designs. We have
also studied flux-pumped metamaterial-based parametric amplifiers, whose
operating frequency can be widely tuned by external DC-flux, and demonstrate
operation at pumping, in contrast to the typical metamaterial
amplifiers pumped via signal lines at .Comment: 9 pages, 6 figure
RSFQ devices with selective dissipation for quantum information processing
We study the possibility to use frequency dependent damping in RSFQ circuits
as means to reduce dissipation and consequent decoherence in RSFQ/qubit
circuits. We show that stable RSFQ operation can be achieved by shunting the
Josephson junctions with an circuit instead of a plain resistor. We derive
criteria for the stability of such an arrangement, and discuss the effect on
decoherence and the optimisation issues. We also design a simple flux generator
aimed at manipulating flux qubits
Monopolelike probes for quantitative magnetic force microscopy: calibration and application
A local magnetization measurement was performed with a Magnetic Force
Microscope (MFM) to determine magnetization in domains of an exchange coupled
[Co/Pt]/Co/Ru multilayer with predominant perpendicular anisotropy. The
quantitative MFM measurements were conducted with an iron filled carbon
nanotube tip, which is shown to behave like a monopole. As a result we
determined an additional in-plane magnetization component of the multilayer,
which is explained by estimating the effective permeability of the sample
within the \mu*-method.Comment: 3 pages, 3 figure
First Calorimetric Measurement of OI-line in the Electron Capture Spectrum of Ho
The isotope Ho undergoes an electron capture process with a
recommended value for the energy available to the decay, , of about
2.5 keV. According to the present knowledge, this is the lowest
value for electron capture processes. Because of that, Ho is the best
candidate to perform experiments to investigate the value of the electron
neutrino mass based on the analysis of the calorimetrically measured spectrum.
We present for the first time the calorimetric measurement of the atomic
de-excitation of the Dy daughter atom upon the capture of an electron
from the 5s shell in Ho, OI-line. The measured peak energy is 48 eV.
This measurement was performed using low temperature metallic magnetic
calorimeters with the Ho ion implanted in the absorber.
We demonstrate that the calorimetric spectrum of Ho can be measured
with high precision and that the parameters describing the spectrum can be
learned from the analysis of the data. Finally, we discuss the implications of
this result for the Electron Capture Ho experiment, ECHo, aiming to
reach sub-eV sensitivity on the electron neutrino mass by a high precision and
high statistics calorimetric measurement of the Ho spectrum.Comment: 5 pages, 3 figure
Four cases of erysipelas-like inflammation in patients with metastatic melanoma treated with checkpoint inhibitors
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Client Weight as a Barrier to Non-Biased Clinical Judgment
A sample of 95 Christian and 68 Non-Christian mental health professionals were given a picture of either an overweight or average-weight male or female client and a generic case vignette. Participants were asked to make clinical judgments of pathology and client attributions for the pictured client. Results indicated that mental health professionals ascribe more pathology and negative attributes to obese clients than to average-weight clients. In addition, Christian mental health professionals are just as likely as non-Christians to ascribe more negative attributes to obese clients. Ways to remove barriers to unbiased psychotherapy and deal with countertransference issues are discussed from a Christian perspective
A Unified Monte Carlo Treatment of Gas-Grain Chemistry for Large Reaction Networks. I. Testing Validity of Rate Equations in Molecular Clouds
In this study we demonstrate for the first time that the unified Monte Carlo
approach can be applied to model gas-grain chemistry in large reaction
networks. Specifically, we build a time-dependent gas-grain chemical model of
the interstellar medium, involving about 6000 gas-phase and 200 grain surface
reactions. This model is used to test the validity of the standard and modified
rate equation methods in models of dense and translucent molecular clouds and
to specify under which conditions the use of the stochastic approach is
desirable.
We found that at temperatures 25--30 K gas-phase abundances of HO,
NH, CO and many other gas-phase and surface species in the stochastic model
differ from those in the deterministic models by more than an order of
magnitude, at least, when tunneling is accounted for and/or diffusion energies
are 3x lower than the binding energies. In this case, surface reactions,
involving light species, proceed faster than accretion of the same species. In
contrast, in the model without tunneling and with high binding energies, when
the typical timescale of a surface recombination is greater than the timescale
of accretion onto the grain, we obtain almost perfect agreement between results
of Monte Carlo and deterministic calculations in the same temperature range. At
lower temperatures ( K) gaseous and, in particular, surface abundances
of most important molecules are not much affected by stochastic processes.Comment: 33 pages, 9 figures, 1 table. Accepted for publication in Ap
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