100 research outputs found
The structure of spinful quantum Hall states: a squeezing perspective
We provide a set of rules to define several spinful quantum Hall model
states. The method extends the one known for spin polarized states. It is
achieved by specifying an undressed root partition, a squeezing procedure and
rules to dress the configurations with spin. It applies to both the
excitation-less state and the quasihole states. In particular, we show that the
naive generalization where one preserves the spin information during the
squeezing sequence, may fail. We give numerous examples such as the Halperin
states, the non-abelian spin-singlet states or the spin-charge separated
states. The squeezing procedure for the series (k=2,r) of spinless quantum Hall
states, which vanish as r powers when k+1 particles coincide, is generalized to
the spinful case. As an application of our method, we show that the counting
observed in the particle entanglement spectrum of several spinful states
matches the one obtained through the root partitions and our rules. This
counting also matches the counting of quasihole states of the corresponding
model Hamiltonians, when the latter is available.Comment: 19 pages, 7 figures; v2: minor changes, and added references.
Mathematica packages are available for downloa
Computation of Casimir forces for dielectrics or intrinsic semiconductors based on the Boltzmann transport equation
The interaction between drifting carriers and traveling electromagnetic waves
is considered within the context of the classical Boltzmann transport equation
to compute the Casimir-Lifshitz force between media with small density of
charge carriers, including dielectrics and intrinsic semiconductors. We expand
upon our previous work [Phys. Rev. Lett. {\bf 101}, 163203 (2008)] and derive
in some detail the frequency-dependent reflection amplitudes in this theory and
compute the corresponding Casimir free energy for a parallel plate
configuration. We critically discuss the the issue of verification of the
Nernst theorem of thermodynamics in Casimir physics, and explicity show that
our theory satisfies that theorem. Finally, we show how the theory of drifting
carriers connects to previous computations of Casimir forces using spatial
dispersion for the material boundaries.Comment: 9 pages, 2 figures; Contribution to Proceedings of "60 Years of the
Casimir Effect", Brasilia, June 200
High-dimensional fractionalization and spinon deconfinement in pyrochlore antiferromagnets
The ground states of Klein type spin models on the pyrochlore and
checkerboard lattice are spanned by the set of singlet dimer coverings, and
thus possess an extensive ground--state degeneracy. Among the many exotic
consequences is the presence of deconfined fractional excitations (spinons)
which propagate through the entire system. While a realistic electronic model
on the pyrochlore lattice is close to the Klein point, this point is in fact
inherently unstable because any perturbation restores spinon
confinement at . We demonstrate that deconfinement is recovered in the
finite--temperature region , where the deconfined phase
can be characterized as a dilute Coulomb gas of thermally excited spinons. We
investigate the zero--temperature phase diagram away from the Klein point by
means of a variational approach based on the singlet dimer coverings of the
pyrochlore lattices and taking into account their non--orthogonality. We find
that in these systems, nearest neighbor exchange interactions do not lead to
Rokhsar-Kivelson type processes.Comment: 19 page
Nematic Structure of Space-Time and its Topological Defects in 5D Kaluza-Klein Theory
We show, that classical Kaluza-Klein theory possesses hidden nematic
dynamics. It appears as a consequence of 1+4-decomposition procedure, involving
4D observers 1-form \lambda. After extracting of boundary terms the, so called,
"effective matter" part of 5D geometrical action becomes proportional to square
of anholonomicity 3-form \lambda\wedge d\lambda. It can be interpreted as twist
nematic elastic energy, responsible for elastic reaction of 5D space-time on
presence of anholonomic 4D submanifold, defined by \lambda. We derive both 5D
covariant and 1+4 forms of 5D nematic equilibrium equations, consider simple
examples and discuss some 4D physical aspects of generic 5D nematic topological
defects.Comment: Latex-2e, 14 pages, 1 Fig., submitted to GR
Casimir-Polder force between an atom and a dielectric plate: thermodynamics and experiment
The low-temperature behavior of the Casimir-Polder free energy and entropy
for an atom near a dielectric plate are found on the basis of the Lifshitz
theory. The obtained results are shown to be thermodynamically consistent if
the dc conductivity of the plate material is disregarded. With inclusion of dc
conductivity, both the standard Lifshitz theory (for all dielectrics) and its
generalization taking into account screening effects (for a wide range of
dielectrics) violate the Nernst heat theorem. The inclusion of the screening
effects is also shown to be inconsistent with experimental data of Casimir
force measurements. The physical reasons for this inconsistency are elucidated.Comment: 10 pages, 1 figure; improved discussion; to appear in J. Phys. A:
Math. Theor. (Fast Track Communications
A q-deformed Aufbau Prinzip
A building principle working for both atoms and monoatomic ions is proposed
in this Letter. This principle relies on the q-deformed chain SO(4) > G where G
= SO(3)_q
Magnetic moment of the two-particle bound state in quantum electrodynamics
We have formulated the quasipotential method for the calculation of the
relativistic and radiative corrections to the magnetic moment of the
two-particle bound state in the case of particles with arbitrary spin. It is
shown that the g-factors of bound particles contain terms
depending on the particle spin. Numerical values for the g-factors of the
electron in the hydrogen atom and deuterium are obtained.Comment: Talk presented at Nuclear Physics Department Conference "Physics of
Fundamental Interactions" Russian Academy of Sciences, ITEP, Moscow, 27
November-1 December 2000. 11 pages, 1 figure uses linedraw.st
Short-Wave Excitations in Non-Local Gross-Pitaevskii Model
It is shown, that a non-local form of the Gross-Pitaevskii equation allows to
describe not only the long-wave excitations, but also the short-wave ones in
the systems with Bose-condensate. At given parameter values, the excitation
spectrum mimics the Landau spectrum of quasi-particle excitations in superfluid
Helium with roton minimum. The excitation wavelength, at which the roton
minimum exists, is close to the inter-particle interaction range. It is shown,
that the existence domain of the spectrum with a roton minimum is reduced, if
one accounts for an inter-particle attraction.Comment: 5 pages, 5 figures, UJP style; presented at Bogolyubov Kyiv
Conference "Modern Problems of Theoretical and Mathematical Physics",
September 15-18, 200
On the use of the group SO(4,2) in atomic and molecular physics
In this paper the dynamical noninvariance group SO(4,2) for a hydrogen-like
atom is derived through two different approaches. The first one is by an
established traditional ascent process starting from the symmetry group SO(3).
This approach is presented in a mathematically oriented original way with a
special emphasis on maximally superintegrable systems, N-dimensional extension
and little groups. The second approach is by a new symmetry descent process
starting from the noninvariance dynamical group Sp(8,R) for a four-dimensional
harmonic oscillator. It is based on the little known concept of a Lie algebra
under constraints and corresponds in some sense to a symmetry breaking
mechanism. This paper ends with a brief discussion of the interest of SO(4,2)
for a new group-theoretical approach to the periodic table of chemical
elements. In this connection, a general ongoing programme based on the use of a
complete set of commuting operators is briefly described. It is believed that
the present paper could be useful not only to the atomic and molecular
community but also to people working in theoretical and mathematical physics.Comment: 31 page
Stripes, Vibrations and Superconductivity
We propose a model of a spatially modulated collective charge state of
superconducting cuprates. The regions of higher carrier density (stripes) are
described in terms of Luttinger liquids and the regions of lower density as a
two-dimensional interacting bosonic gas of d_{x^2-y^2} hole pairs. The
interactions among the elementary excitations are repulsive and the transition
to the superconducting state is driven by decay processes. Vibrations of the
CCS and the lattice, although not participating directly in the binding
mechanism, are fundamental for superconductivity. The superfluid density and
the lattice have a strong tendency to modulation implying a still unobserved
dimerized stripe phase in cuprates. The phase diagram of the model has a
crossover from 1D to 2D behavior and a pseudogap region where the amplitude of
the order parameters are finite but phase coherence is not established. We
discuss the nature of the spin fluctuations and the unusual isotope effect
within the model.Comment: 51 pages, 20 figures. Post-March Meeting version: New references are
added, some of the typos are corrected, and a few new discussions are
include
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