1,298 research outputs found
Quantum turnstile operation of single-molecule magnets
The time-dependent transport through single-molecule magnets coupled to
magnetic or non-magnetic electrodes is studied in the framework of the
generalized master equation method. We investigate the transient regime induced
by the periodic switching of the source and drain contacts. If the electrodes
have opposite magnetizations the quantum turnstile operation allows the
stepwise writing of intermediate excited states. In turn, the transient
currents provide a way to read these states. Within our approach we take into
account both the uniaxial and transverse anisotropy. The latter may induce
additional quantum tunneling processes which affect the efficiency of the
proposed read-and-write scheme. An equally weighted mixture of molecular spin
states can be prepared if one of the electrodes is ferromagnetic.Comment: 19 pages, 6 figure
Coulomb oscillations of the Fano-Kondo effect and zero bias anomalies in the double dot meso-transistor
We investigate theoretically the transport properties of the side-coupled
double quantum dots in connection with the experimental study of Sasaki {\it et
al.} Phys.Rev.Lett.{\bf 103}, 266806 (2009). The novelty of the set-up consists
in connecting the Kondo dot directly to the leads, while the side dot provides
an interference path which affects the Kondo correlations. We analyze the
oscillations of the source-drain current due to the periodical Coulomb blockade
of the many-level side-dot at the variation of the gate potential applied on
it. The Fano profile of these oscillations may be controlled by the
temperature, gate potential and interdot coupling. The non-equilibrium
conductance of the double dot system exhibits zero bias anomaly which, besides
the usual enhancement, may show also a suppression (a dip-like aspect) which
occurs around the Fano {\it zero}. In the same region, the weak temperature
dependence of the conductance indicates the suppression of the Kondo effect.
Scaling properties of the non-equilibrium conductance in the Fano-Kondo regime
are discussed. Since the SIAM Kondo temperature is no longer the proper scaling
parameter, we look for an alternative specific to the double-dot. The extended
Anderson model, Keldysh formalism and equation of motion technique are used.Comment: 19 pages, 8 figure
Infra-red divergences in plane wave backgrounds
We show that the emission of soft photons via nonlinear Compton scattering in
a pulsed plane wave (laser field) is in general infra-red divergent. We give
examples of both soft and soft-collinear divergences, and we pay particular
attention to the case of crossed fields in both classical and quantum theories.Comment: 15 pages, 7 figure
фольклорно-етнографічні матеріали на сторінках журналу «Основа»
In the article folk and ethnographical materials of the «Osnova» magazine are analyzed. The role of this edition in development of the ethnography is defined
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