1,300 research outputs found
Reduced frequency noise in superconducting resonators
We report a reduction of the frequency noise in coplanar waveguide
superconducting resonators. The reduction of 7 dB is achieved by removing the
exposed dielectric substrate surface from the region with high electric fields
and by using NbTiN. In a model-analysis the surface of NbTiN is found to be a
negligible source of noise, experimentally supported by a comparison with NbTiN
on SiOx resonators. The reduction is additive to decreasing the noise by
widening the resonators.Comment: 4 pages, 4 figure
Quasiparticle relaxation in optically excited high-Q superconducting resonators
The quasiparticle relaxation time in superconducting films has been measured
as a function of temperature using the response of the complex conductivity to
photon flux. For tantalum and aluminium, chosen for their difference in
electron-phonon coupling strength, we find that at high temperatures the
relaxation time increases with decreasing temperature, as expected for
electron-phonon interaction. At low temperatures we find in both
superconducting materials a saturation of the relaxation time, suggesting the
presence of a second relaxation channel not due to electron-phonon interaction.Comment: 4 pages, 3 figure
Enhancement of quasiparticle recombination in Ta and Al superconductors by implantation of magnetic and nonmagnetic atoms
The quasiparticle recombination time in superconducting films, consisting of
the standard electron-phonon interaction and a yet to be identified low
temperature process, is studied for different densities of magnetic and
nonmagnetic atoms. For both Ta and Al, implanted with Mn, Ta and Al, we observe
an increase of the recombination rate. We conclude that the enhancement of
recombination is not due to the magnetic moment, but arises from an enhancement
of disorder.Comment: 4 pages, 4 figure
Food neophobia and mealtime food consumption in 4-5 year old children.
Background: Previous research has documented a negative association between maternal report
of child food neophobia and reported frequency of consumption of fruit, vegetables, and meat. This
study aimed to establish whether neophobia is associated with lower intake of these food types in
naturalistic mealtime situations.
Methods: One hundred and nine parents of 4–5 year olds completed questionnaires which
included a six-item version of the Child Food Neophobia Scale (CFNS). The children took part in
a series of 3 test lunch meals at weekly intervals at school at which they were presented with:
chicken, cheese, bread, cheese crackers, chocolate biscuits, grapes and tomatoes or carrot sticks.
Food items served to each child were weighed before and after the meal to assess total intake of
items in four categories: Fruit and vegetables, Protein foods, Starchy foods and Snack foods.
Pearson Product Moment Correlations and independent t tests were performed to examine
associations between scores on the CFNS and consumption during lunches.
Results: Neophobia was associated with lower consumption of fruit and vegetables, protein foods
and total calories, but there was no association with intake of starch or snack foods.
Conclusion: These results support previous research that has suggested that neophobia impacts
differentially on consumption of different food types. Specifically it appears that children who score
highly on the CFNS eat less fruit, vegetables and protein foods than their less neophobic peers.
Attempts to increase intake of fruit, vegetables and protein might usefully incorporate strategies
known to reduce the neophobic response
Integrated Filterbank for DESHIMA: A Submillimeter Imaging Spectrograph Based on Superconducting Resonators
An integrated filterbank (IFB) in combination with microwave kinetic
inductance detectors (MKIDs), both based on superconducting resonators, could
be used to make broadband submillimeter imaging spectrographs that are compact
and flexible. In order to investigate the possibility of adopting an IFB
configuration for DESHIMA (Delft SRON High-redshift Mapper), we study the basic
properties of a coplanar-waveguide-based IFB using electromagnetic simulation.
We show that a coupling efficiency greater than 1/2 can be achieved if
transmission losses are negligible. We arrive at a practical design for a 9
pixel x 920 color 3 dimensional imaging device that fits on a 4 inch wafer,
which instantaneously covers multiple submillimeter telluric windows with a
dispersion of f/df = 1000.Comment: 6 pages, 4 figures, submitted to LTD-14 / Journal of Low Temperature
Physic
Multiplexed dispersive readout of superconducting phase qubits
We introduce a frequency-multiplexed readout scheme for superconducting phase
qubits. Using a quantum circuit with four phase qubits, we couple each qubit to
a separate lumped-element superconducting readout resonator, with the readout
resonators connected in parallel to a single measurement line. The readout
resonators and control electronics are designed so that all four qubits can be
read out simultaneously using frequency multiplexing on the one measurement
line. This technology provides a highly efficient and compact means for reading
out multiple qubits, a significant advantage for scaling up to larger numbers
of qubits.Comment: 4 pages, 4 figure
- …