1,678 research outputs found
Probability distribution function of dipolar field in two-dimensional spin ensemble
We theoretically determine the probability distribution function of the net
field of the random planar structure of dipoles which represent polarized
particles. At small surface concentrations c of the point dipoles this
distribution is expressed in terms of special functions. At the surface
concentrations of the dipoles as high as 0.6 the dipolar field obey the
Gaussian law. To obtain the distribution function within transitional region
c<0.6, we propose the method based on the cumulant expansion. We calculate the
parameters of the distributions for some specific configurations of the
dipoles. The distribution functions of the ordered ensembles of the dipoles at
the low and moderate surface concentrations have asymmetric shape with respect
to distribution medians. The distribution functions allow to calculate various
physical parameters of two-dimensional interacting nanoparticle ensembles.Comment: 9 pages, 3 figure
Superconductivity in model cuprate as an S=1 pseudomagnon condensation
We make use of the S=1 pseudospin formalism to describe the charge degree of
freedom in a model high- cuprate with the on-site Hilbert space reduced to
the three effective valence centers, nominally Cu. Starting
with a parent cuprate as an analogue of the quantum paramagnet ground state and
using the Schwinger boson technique we found the pseudospin spectrum and
conditions for the pseudomagnon condensation with phase transition to a
superconducting state.Comment: Version to be published in JLT
Total Quantum Zeno effect and Intelligent States for a two level system in a squeezed bath
In this work we show that by frequent measurements of adequately chosen
observables, a complete suppression of the decay in an exponentially decaying
two level system interacting with a squeezed bath is obtained. The observables
for which the effect is observed depend on the the squeezing parameters of the
bath. The initial states which display Total Zeno Effect are intelligent states
of two conjugate observables associated to the electromagnetic fluctuations of
the bath.Comment: 5 pages, 3 figure
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