25 research outputs found
Algebraic construction of quantum integrable models including inhomogeneous models
Exploiting the quantum integrability condition we construct an ancestor model
associated with a new underlying quadratic algebra. This ancestor model
represents an exactly integrable quantum lattice inhomogeneous anisotropic
model and at its various realizations and limits can generate a wide range of
integrable models. They cover quantum lattice as well as field models
associated with the quantum -matrix of trigonometric type or at the
undeformed limit similar models belonging to the rational class. The
classical limit likewise yields the corresponding classical discrete and field
models. Thus along with the generation of known integrable models in a unifying
way a new class of inhomogeneous models including variable mass sine-Gordon
model, inhomogeneous Toda chain, impure spin chains etc. are constructed.Comment: Latex, 14pages, To be published in the Rev. Math. Phys annual
conf.ROMP99 Proceedings (Tarun, Poland, 1999
Evidence of a new state in Be observed in the Li -decay
Coincidences between charged particles emitted in the -decay of
Li were observed using highly segmented detectors. The breakup channels
involving three particles were studied in full kinematics allowing for the
reconstruction of the excitation energy of the Be states participating
in the decay. In particular, the contribution of a previously unobserved state
at 16.3 MeV in Be has been identified selecting the +
He + He+n channel. The angular correlations between the
particle and the center of mass of the He+n system favors spin and
parity assignment of 3/2 for this state as well as for the previously known
state at 18 MeV.Comment: 13 pages, 6 figure
Algebraic approach in unifying quantum integrable models
A novel algebra underlying integrable systems is shown to generate and unify
a large class of quantum integrable models with given -matrix, through
reductions of an ancestor Lax operator and its different realizations. Along
with known discrete and field models a new class of inhomogeneous and impurity
models are obtained.Comment: Revtex, 6 pages, no figure, revised version to be published in Phys.
Rev. Lett., 199
Wigner functions, squeezing properties and slow decoherence of atomic Schrodinger cats
We consider a class of states in an ensemble of two-level atoms: a
superposition of two distinct atomic coherent states, which can be regarded as
atomic analogues of the states usually called Schrodinger cat states in quantum
optics. According to the relation of the constituents we define polar and
nonpolar cat states. The properties of these are investigated by the aid of the
spherical Wigner function. We show that nonpolar cat states generally exhibit
squeezing, the measure of which depends on the separation of the components of
the cat, and also on the number of the constituent atoms. By solving the master
equation for the polar cat state embedded in an external environment, we
determine the characteristic times of decoherence, dissipation and also the
characteristic time of a new parameter, the non-classicality of the state. This
latter one is introduced by the help of the Wigner function, which is used also
to visualize the process. The dependence of the characteristic times on the
number of atoms of the cat and on the temperature of the environment shows that
the decoherence of polar cat states is surprisingly slow.Comment: RevTeX, 14 pages including 8 PostScript figures. High quality
versions of Figures 1, 3, 5, 7 and 8 are available at
http://www.jate.u-szeged.hu/~benedict/asc_figures.html . (Submitted to
Physical Review A: March 26, 1999.