11,295 research outputs found
Quantum dynamics of a dc-SQUID coupled to an asymmetric Cooper pair transistor
We present a theoretical analysis of the quantum dynamics of a
superconducting circuit based on a highly asymmetric Cooper pair transistor
(ACPT) in parallel to a dc-SQUID. Starting from the full Hamiltonian we show
that the circuit can be modeled as a charge qubit (ACPT) coupled to an
anharmonic oscillator (dc-SQUID). Depending on the anharmonicity of the SQUID,
the Hamiltonian can be reduced either to one that describes two coupled qubits
or to the Jaynes-Cummings Hamiltonian. Here the dc-SQUID can be viewed as a
tunable micron-size resonator. The coupling term, which is a combination of a
capacitive and a Josephson coupling between the two qubits, can be tuned from
the very strong- to the zero-coupling regimes. It describes very precisely the
tunable coupling strength measured in this circuit and explains the
'quantronium' as well as the adiabatic quantum transfer read-out.Comment: 20 page
Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic): Alewife/Blueback Herring
This profile covers life history
and environmental requirements of
both alewife (Alosa pseudoharengus)
and blueback herring (Alosa aestivalis),
since their distribution is
overlapping and their morphology,
ecological role, and environmental
requirements are similar.
The alewife is
an anadromous species found in
riverine, estuarine, and Atlantic
coastal habitats, depending on
life cycle stage, from Newfoundland
(Winters et al. 1973) to
Soutn Carolina (Berry 1964).
Landlocked populations are i n the
Great Lakes, Finger Lakes, and
many other freshwater lakes
(Bigelow and Sch roeder 1953;
Scott and Crossman 1973). The
blueback herring is an anadromous
species found in riverine,
estuarine, and Atlantic coastal
habitats, depending on life stage
cycle, from Nova Scotia to the
St. Johns River, Florida (Hildebrand
1963
Scanner observations of selected cool stars
Photoelectric spectral scans at 30-A resolution of 9 dwarfs, 10 giants and 6 supergiants with spectral types GO to M5 were presented. All stars were observed every 4 A from wavelength 3300 to wavelength 7000. Absorption features at this resolution coincide with: strong atomic lines of Fe 1,11, Ca 1,11, Mg 1, and Na 1; vibrational bands of the electronic transitions of TiO, MgH, CaH, SiH, AlH, Cn, Ch, C2, OH, and NH. The dependence of the wavelength 3740 Fe 1 blend and the wavelength 3440 depression on temperature is discussed
John Wesley’s Motivation for His Mission to Georgia
The importance of justification by faith in the thinking of John Wesley (1703-1791) after his Aldersgate Street experience in May 1738 has long been doubted by some Wesley scholars. This article argues, however, that Wesley was motivated only by works-righteousness while he was a missionary to Georgia, and that salvation by faith did not characterise his thinking until he finished his mission there
Impact of disorder on unconventional superconductors with competing ground states
Non-magnetic impurities are known as strong pair breakers in superconductors
with pure d-wave pairing symmetry. Here we discuss d-wave states under the
combined influence of impurities and competing instabilities, such as pairing
in a secondary channel as well as lattice symmetry breaking. Using the
self-consistent T-matrix formalism, we show that disorder can strongly modify
the competition between different pairing states. For a d-wave superconductor
in the presence of a subdominant local attraction, Anderson's theorem implies
that disorder always generates an s-wave component in the gap at sufficiently
low temperature, even if a pure d_{x^2-y^2} order parameter characterizes the
clean system. In contrast, disorder is always detrimental to an additional
d_{xy} component. This qualitative difference suggests that disorder can be
used to discriminate among different mixed-gap structures in high-temperature
superconductors. We also investigate superconducting phases with lattice
symmetry breaking in the form of bond order, and show that the addition of
impurities quickly leads to the restoration of translation invariance. Our
results highlight the importance of controlling disorder for the observation of
competing order parameters in cuprates.Comment: 13 pages, 10 figure
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