3,349 research outputs found
Quantum Energy Teleportation in Spin Chain Systems
We propose a protocol for quantum energy teleportation which transports
energy in spin chains to distant sites only by local operations and classical
communication. By utilizing ground-state entanglement and notion of negative
energy density region, energy is teleported without breaking any physical laws
including causality and local energy conservation. Because not excited physical
entity but classical information is transported in the protocol, the
dissipation rate of energy in transport is expected to be strongly suppressed.Comment: 22 pages, 4 figure, to be published in JPS
Generation of twist on magnetic flux tubes at the base of the solar convection zone
Using two-dimensional magnetohydrodynamics calculations, we investigate a
twist gen- eration mechanism on a magnetic flux tube at the base of the solar
convection zone based on the idea of Choudhuri, 2003, Sol. Phys., 215, 31 in
which a toroidal mag- netic field is wrapped by a surrounding mean poloidal
field. During generation of the twist, the flux tube follows four phases. (1)
It quickly splits into two parts with vortex motions rolling up the poloidal
magnetic field. (2) Owing to the physical mechanism similar to that of the
magneto-rotational instability, the rolled-up poloidal field is bent and
amplified. (3) The magnetic tension of the disturbed poloidal magnetic field
re- duces the vorticity, and the lifting force caused by vortical motion
decreases. (4) The flux tube gets twisted and begins to rise again without
splitting. Investigation of these processes is significant because it shows
that a flux tube without any initial twist can rise to the surface in
relatively weak poloidal fields.Comment: 10 pages, 6 figur
Kondo Effect in an Electron System with Dynamical Jahn-Teller Impurity
We investigate how Kondo phenomenon occurs in the Anderson model dynamically
coupled with local Jahn-Teller phonons. It is found that the total angular
moment composed of electron pseudo-spin and phonon angular moments is screened
by conduction electrons. Namely, phonon degrees of freedom essentially
contribute to the formation of singlet ground state. A characteristic
temperature of the Kondo effect due to dynamical Jahn-Teller phonons is
explained by an effective - Hamiltonian with anisotropic exchange
interaction obtained from the Jahn-Teller-Anderson model in a non-adiabatic
region.Comment: 5 pages, 3 figure
Quasi-Kondo Phenomenon due to Dynamical Jahn-Teller Effect
A mechanism of non-magnetic Kondo effect is proposed on the basis of a
multiorbital Anderson model coupled with dynamical Jahn-Teller (JT) phonons. An
electron system coupled dynamically with JT phonons has a vibronic ground state
with double degeneracy due to clockwise and anti-clockwise rotational modes
with entropy of . When a temperature is lower than a characteristic
energy to turn the rotational direction, the rotational degree of freedom is
eventually suppressed and the corresponding entropy is released,
leading to quasi-Kondo behavior. We discuss possible relevance of this
quasi-Kondo phenomenon to electronic properties of filled skutterudites.Comment: 4 pages, 3 figure
Quadrupole Susceptibility of Gd-Based Filled Skutterudite Compounds
It is shown that quadrupole susceptibility can be detected in Gd compounds
contrary to our textbook knowledge that Gd ion induces pure spin moment
due to the Hund's rules in an coupling scheme. The ground-state multiplet
of Gd is always characterized by =7/2, where denotes total
angular momentum, but in a - coupling scheme, one electron in =7/2
octet carries quadrupole moment, while other six electrons fully occupy =5/2
sextet, where denotes one-electron total angular momentum. For realistic
values of Coulomb interaction and spin-orbit coupling, the ground-state
wavefunction is found to contain significant amount of the - coupling
component. From the evaluation of quadrupole susceptibility in a simple
mean-field approximation, we point out a possibility to detect the softening of
elastic constant in Gd-based filled skutterudites.Comment: 8 pages, 4 figure
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