1,615 research outputs found
Quantum mutual entropy for Jaynes-Cummings model
The dynamics of an atom on the Jaynes-Cummings model has been studied by an
atomic inversion, von Neumann entropy and so on. In this letter, we will treat
the Jaynes-Cummings model as a problem in non-equilibrium statistical mechanics
and apply quantum mutual entropy to study the irreversible dynamics of a state
for the atom on this model.Comment: RevTeX, 4 pages with a figure(eps file), submitted to Physical Review
Letter
Entanglement in thermal equilibrium states
We revisist the issue of entanglement of thermal equilibrium states in
composite quantum systems. The possible scenarios are exemplified in bipartite
qubit/qubit and qubit/qutrit systems.Comment: 4 figure
Entropy reduction of quantum measurements
It is observed that the entropy reduction (the information gain in the
initial terminology) of an efficient (ideal or pure) quantum measurement
coincides with the generalized quantum mutual information of a q-c channel
mapping an a priori state to the corresponding posteriori probability
distribution of the outcomes of the measurement. This observation makes it
possible to define the entropy reduction for arbitrary a priori states (not
only for states with finite von Neumann entropy) and to study its analytical
properties by using general properties of the quantum mutual information.
By using this approach one can show that the entropy reduction of an
efficient quantum measurement is a nonnegative lower semicontinuous concave
function on the set of all a priori states having continuous restrictions to
subsets on which the von Neumann entropy is continuous. Monotonicity and
subadditivity of the entropy reduction are also easily proved by this method.
A simple continuity condition for the entropy reduction and for the mean
posteriori entropy considered as functions of a pair (a priori state,
measurement) is obtained.
A characterization of an irreducible measurement (in the Ozawa sense) which
is not efficient is considered in the Appendix.Comment: 21 pages, minor corrections have been mad
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