7,667 research outputs found
Resonant effects in the strongly driven phase-biased Cooper-pair box
We study the time-averaged upper level occupation probability in a strongly
driven two level system, particularly its dependence on the driving amplitude,
frequency and the energy level separation. In contrast to the case of weak
driving, when the positions of the resonances almost do not depend on the
driving amplitude, in the case of the strong diving their positions are
strongly amplitude-dependent. We study these resonances in the concrete system
-- the strongly driven phase-biased Cooper-pair box, which is considered to be
weakly coupled to the tank circuit
Josephson and spontaneous currents at the interface between two d-wave superconductors with transport current in the banks
A stationary Josephson effect in the ballistic contact of two d-wave
superconductors with different axes orientation and with tangential transport
current in the banks is considered theoretically. We study the influence of the
transport current on the current-phase dependence for the Josephson and
tangential currents at the interface. It is demonstrated that the spontaneous
surface current at the interface depends on the transport current in the banks
due to the interference of the angle-dependent current-carrying condensate wave
functions of the two superconductors.Comment: to be published in Fiz. Nizk. Temp. (Sov. J. Low Temp. Phys.),
Vol.30, No.3 (2004
NLO QCD method of the polarized SIDIS data analysis
Method of polarized semi-inclusive deep inelastic scattering (SIDIS) data
analysis in the next to leading order (NLO) QCD is developed. Within the method
one first directly extracts in NLO few first truncated (available to
measurement) Mellin moments of the quark helicity distributions. Second, using
these moments as an input to the proposed modification of the Jacobi polynomial
expansion method (MJEM), one eventually reconstructs the local quark helicity
distributions themselves. All numerical tests demonstrate that MJEM allows us
to reproduce with the high precision the input local distributions even inside
the narrow Bjorken region accessible for experiment. It is of importance
that only four first input moments are sufficient to achieve a good quality of
reconstruction. The application of the method to the simulated SIDIS data on
the pion production is considered. The obtained results encourage one that the
proposed NLO method can be successfully applied to the SIDIS data analysis. The
analysis of HERMES data on pion production is performed. To this end the pion
difference asymmetries are constructed from the measured by HERMES standard
semi-inclusive spin asymmetries. The LO results of the valence distribution
reconstruction are in a good accordance with the respective leading order SMC
and HERMES results, while the NLO results are in agreement with the existing
NLO parametrizations on these quantities
Conductance characteristics of current-carrying d-wave weak links
The local quasiparticle density of states in the current-carrying d-wave
superconducting structures was studied theoretically. The density of states can
be accessed through the conductance of the scanning tunnelling microscope. Two
particular situations were considered: the current state of the homogeneous
film and the weak link between two current-carrying d-wave superconductors.Comment: 4 pages, 3 figures; to appear in Low. Temp. Phy
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