36,881 research outputs found
Coupled ion - nanomechanical systems
We study ions in a nanotrap, where the electrodes are nanomechanical
resonantors. The ions play the role of a quantum optical system which acts as a
probe and control, and allows entanglement with or between nanomechanical
resonators.Comment: 4 pages, 2 figures, submitted for publicatio
Algebraic Structures Derived from Foams
Foams are surfaces with branch lines at which three sheets merge. They have
been used in the categorification of sl(3) quantum knot invariants and also in
physics. The 2D-TQFT of surfaces, on the other hand, is classified by means of
commutative Frobenius algebras, where saddle points correspond to
multiplication and comultiplication. In this paper, we explore algebraic
operations that branch lines derive under TQFT. In particular, we investigate
Lie bracket and bialgebra structures. Relations to the original Frobenius
algebra structures are discussed both algebraically and diagrammatically.Comment: 11 pages; 14 figure
Deconfinement in the Quark Meson Coupling Model
The Quark Meson Coupling Model which describes nuclear matter as a collection
of non-overlapping MIT bags interacting by the self-consistent exchange of
scalar and vector mesons is used to study nuclear matter at finite temperature.
In its modified version, the density dependence of the bag constant is
introduced by a direct coupling between the bag constant and the scalar mean
field. In the present work, the coupling of the scalar mean field with the
constituent quarks is considered exactly through the solution of the Dirac
equation. Our results show that a phase transition takes place at a critical
temperature around 200 MeV in which the scalar mean field takes a nonzero value
at zero baryon density. Furthermore it is found that the bag constant decreases
significantly when the temperature increases above this critical temperature
indicating the onset of quark deconfinement.Comment: LaTeX/TeX 15 pages (zk2.tex)+ 6 figures in TeX forma
Heat conductivity in small quantum systems: Kubo formula in Liouville space
We consider chains consisting of several identical subsystems weakly coupled
by various types of next neighbor interactions. At both ends the chain is
coupled to a respective heat bath with different temperature modeled by a
Lindblad formalism. The temperature gradient introduced by this environment is
then treated as an external perturbation. We propose a method to evaluate the
heat current and the local temperature profile of the resulting stationary
state as well as the heat conductivity in such systems. This method is similar
to Kubo techniques used e.g. for electrical transport but extended here to the
Liouville space.Comment: 6 pages, 1 figur
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