4,904 research outputs found
Mesoscopic superconductors under irradiation: Microwave spectroscopy of Andreev states
We show that irradiation of a voltage-biased superconducting quantum point
contact at frequencies of the order of the gap energy can remove the
suppression of subgap dc transport through Andreev levels. Quantum interference
among resonant scattering events involving photon absorption is furthermore
shown to make microwave spectroscopy of the Andreev levels feasible. We also
discuss how the same interference effect can be applied for detecting weak
electromagnetic signals up to the gap frequency, and how it is affected by
dephasing and relaxation.Comment: Submitted to a special volume of "Superlattices and Microstructures"
on Mesoscopic Superconductivit
On a generic Verma module at the critical level over affine Lie superalgebras
We describe the structure of a Verma module with a generic highest weight at
the critical level over a symmetrizable affine Lie superalgebra not of the type
A(2k,2l)^{(4)}. We obtain the character formula for a simple module with a
generic highest weight at the critical level conjectured by V. G. Kac and D. A.
Kazhdan.Comment: considerably revised text, including the title; 33 page
MICROWAVE-INDUCED RESONANT REFLECTION AND LOCALIZATION OF BALLISTIC ELECTRONS IN QUANTUM MICROCHANNELS
We show that electron transport in a ballistic microchannel supporting both
propagating and reflected modes can be completely blocked by applying a
microwave electromagnetic field. The effect is due to resonant reflection
caused by multiple coherent electron-photon scattering involving at least two
spatially localized scattering centers in the channel. With many such
scattering centers present the conductance is shown to have an irregular
dependence on bias voltage, gate voltage and frequency with irregularily spaced
dips corresponding to resonant reflection. When averaged over bias, gate
voltage or frequency the conductance will decay exponentially with channel
length in full analogy with the localization of 1D electrons caused by impurity
scattering.Comment: 4 pages, latex, 1 figure available on reques
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