1,930 research outputs found
Electron Transport in Double Quantum Dot governed by Nuclear Magnetic Field
We investigate theoretically electron transfer in a doble dot in a situation
where it is governed by nuclear magnetic field: This has been recently achieved
in experiment. We show how to partially compensate the nuclear magnetic field
to restore Spin Blockade
The Effect of Mechanical Resonance on Josephson Dynamics
We study theoretically dynamics in a Josephson junction coupled to a
mechanical resonator looking at the signatures of the resonance in d.c.
electrical response of the junction. Such a system can be realized
experimentally as a suspended ultra-clean carbon nanotube brought in contact
with two superconducting leads. A nearby gate electrode can be used to tune the
junction parameters and to excite mechanical motion. We augment theoretical
estimations with the values of setup parameters measured in the samples
fabricated.
We show that charging effects in the junction give rise to a mechanical force
that depends on the superconducting phase difference. The force can excite the
resonant mode provided the superconducting current in the junction has
oscillating components with a frequency matching the resonant frequency of the
mechanical resonator. We develop a model that encompasses the coupling of
electrical and mechanical dynamics. We compute the mechanical response (the
effect of mechanical motion) in the regime of phase bias and d.c. voltage bias.
We thoroughly investigate the regime of combined a.c. and d.c. bias where
Shapiro steps are developed and reveal several distinct regimes characteristic
for this effect. Our results can be immediately applied in the context of
experimental detection of the mechanical motion in realistic superconducting
nano-mechanical devices.Comment: 18 pages, 11 figure
Casimir elements from the Brauer-Schur-Weyl duality
We consider Casimir elements for the orthogonal and symplectic Lie algebras
constructed with the use of the Brauer algebra. We calculate the images of
these elements under the Harish-Chandra isomorphism and thus show that they
(together with the Pfaffian-type element in the even orthogonal case) are
algebraically independent generators of the centers of the corresponding
universal enveloping algebras.Comment: 19 page
On irreducibility of tensor products of evaluation modules for the quantum affine algebra
Every irreducible finite-dimensional representation of the quantized
enveloping algebra U_q(gl_n) can be extended to the corresponding quantum
affine algebra via the evaluation homomorphism. We give in explicit form the
necessary and sufficient conditions for irreducibility of tensor products of
such evaluation modules.Comment: 22 pages. Some references are adde
Irreducibility of fusion modules over twisted Yangians at generic point
With any skew Young diagram one can associate a one parameter family of
"elementary" modules over the Yangian \Yg(\g\l_N). Consider the twisted
Yangian \Yg(\g_N)\subset \Yg(\g\l_N) associated with a classical matrix Lie
algebra \g_N\subset\g\l_N. Regard the tensor product of elementary Yangian
modules as a module over \Yg(\g_N) by restriction. We prove its
irreducibility for generic values of the parameters.Comment: Replaced with journal version, 18 page
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