15,459 research outputs found
Thermopower-based hot electron thermometry of helium surface states at 1.6 K
We have developed a method to probe the temperature of surface state
electrons (SSE) above a superfluid Helium-4 surface using the Seebeck effect.
In contrast to previously used SSE thermometry, this technique does not require
detailed knowledge of the non-linear mobility. We demonstrate the use of this
method by measuring energy relaxation of SSE at 1.6 K in a microchannel device
with 0.6\:\mu\mbox{m} deep helium. In this regime, both vapor atom scattering
and 2-ripplon scattering contribute to energy relaxation to which we compare
our measurements. We conclude that this technique provides a reliable measure
of electron temperature while requiring a less detailed understanding of the
electron interactions with the environment than previously utilized thermometry
techniques
Anisotropic Stark Effect and Electric-Field Noise Suppression for Phosphorus Donor Qubits in Silicon
We report the use of novel, capacitively terminated coplanar waveguide (CPW)
resonators to measure the quadratic Stark shift of phosphorus donor qubits in
Si. We confirm that valley repopulation leads to an anisotropic spin-orbit
Stark shift depending on electric and magnetic field orientations relative to
the Si crystal. By measuring the linear Stark effect, we estimate the effective
electric field due to strain in our samples. We show that in the presence of
this strain, electric-field sources of decoherence can be non-negligible. Using
our measured values for the Stark shift, we predict magnetic fields for which
the spin-orbit Stark effect cancels the hyperfine Stark effect, suppressing
decoherence from electric-field noise. We discuss the limitations of these
noise-suppression points due to random distributions of strain and propose a
method for overcoming them
Understanding Caregiver Factors Influencing Childhood Influenza Vaccination
Influenza is a contagious disease that affects approximately 30% to 40% of American children yearly, and all children 18 and under are recommended to be vaccinated. Through the use of a survey tool, 119 responses were collected about the factors that influence the decisions of caregivers whether or not to vaccinate their children against influenza. The knowledge generated from the survey may be used to formulate education programs to increase vaccination rates
Simultaneous use of LANDSAT digital data with that of geophysical and geological surveys in geomathematical modelling for mineral exploration prediction
The author has identified the following significant results. A computer test file was created for the analysis of two rows in the pilot area. Data were organized into two groups with and without radioactivity above 1200 counts. The first 42 samples corresponded to the geographic cells which were anomalous, and the rest of the samples (70) were without anomalous values. Output analysis shows that all samples were properly classified
Electron Spin Resonance at the Level of 10000 Spins Using Low Impedance Superconducting Resonators
We report on electron spin resonance (ESR) measurements of phosphorus donors
localized in a 200 square micron area below the inductive wire of a lumped
element superconducting resonator. By combining quantum limited parametric
amplification with a low impedance microwave resonator design we are able to
detect around 20000 spins with a signal-to-noise ratio (SNR) of 1 in a single
shot. The 150 Hz coupling strength between the resonator field and individual
spins is significantly larger than the 1 - 10 Hz coupling rates obtained with
typical coplanar waveguide resonator designs. Due to the larger coupling rate,
we find that spin relaxation is dominated by radiative decay into the resonator
and dependent upon the spin-resonator detuning, as predicted by Purcell
Reevaluation of the normative minerals of Sonora Pass rock standards - University of Nevada reports 7 and 12
Chemical analyses and normative minerals of Nevada mountain pass rock
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