1,676 research outputs found
Evolution of the N ion Jaynes-Cummings model beyond the standard rotating wave approximation
A unitary transformation of the N-ion Jaynes-Cummings hamiltonian is
proposed. It is shown that any approximate expression of the evolution operator
associated with the transformed hamiltonian retains its validity independently
from the intensity of the external driving field. In particular, using the
rotating wave approximation, one obtains a solution for the N-ion
Jaynes-Cummings model which improves the standard rotating wave approximation
solution.Comment: Presented at the Wigner Centennial Conference (Pecs, Hungary, July
2002) (to appear on Journal of Optics B, provisionally scheduled for June
2003 issue
On Reduced Time Evolution for Initially Correlated Pure States
A new method to deal with reduced dynamics of open systems by means of the
Schr\"odinger equation is presented. It allows one to consider the reduced time
evolution for correlated and uncorrelated initial conditions.Comment: accepted in Open Sys. Information Dy
Remarks on the star product of functions on finite and compact groups
Using the formalism of quantizers and dequantizers, we show that the
characters of irreducible unitary representations of finite and compact groups
provide kernels for star products of complex-valued functions of the group
elements. Examples of permutation groups of two and three elements, as well as
the SU(2) group, are considered. The k-deformed star products of functions on
finite and compact groups are presented. The explicit form of the quantizers
and dequantizers, and the duality symmetry of the considered star products are
discussed.Comment: 17 pages, minor changes with respect to the published version of the
pape
Tensorial characterization and quantum estimation of weakly entangled qubits
In the case of two qubits, standard entanglement monotones like the linear
entropy fail to provide an efficient quantum estimation in the regime of weak
entanglement. In this paper, a more efficient entanglement estimation, by means
of a novel class of entanglement monotones, is proposed. Following an approach
based on the geometric formulation of quantum mechanics, these entanglement
monotones are defined by inner products on invariant tensor fields on bipartite
qubit orbits of the group SU(2)xSU(2).Comment: 23 pages, 3 figure
A class of commutative dynamics of open quantum systems
We analyze a class of dynamics of open quantum systems which is governed by
the dynamical map mutually commuting at different times. Such evolution may be
effectively described via spectral analysis of the corresponding time dependent
generators. We consider both Markovian and non-Markovian cases.Comment: 22 page
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