53,189 research outputs found
Luttinger States at the Edge
An effective wavefunction for the edge excitations in the Fractional quantum
Hall effect can be found by dimensionally reducing the bulk wavefunction.
Treated this way the Laughlin wavefunction yields a Luttinger
model ground state. We identify the edge-electron field with a Luttinger
hyper-fermion operator, and the edge electron itself with a non-backscattering
Bogoliubov quasi-particle. The edge-electron propagator may be calculated
directly from the effective wavefunction using the properties of a
one-dimensional one-component plasma, provided a prescription is adopted which
is sensitive to the extra flux attached to the electrons
Fatalism and Future Contingents
In this paper I address issues related to the problem of future contingents and
the metaphysical doctrine of fatalism. Two classical responses to the problem of
future contingents are the third truth value view and the all-false view. According to
the former, future contingents take a third truth value which goes beyond truth and
falsity. According to the latter, they are all false. I here illustrate and discuss two
ways to respectively argue for those two views. Both ways are similar in spirit and
intimately connected with fatalism, in the sense that they engage with the doctrine
of fatalism and accept a large part of a standard fatalistic machinery
Scaling and interaction-assisted transport in graphene with one-dimensional defects
We analyze the scattering from one-dimensional defects in intrinsic graphene.
The Coulomb repulsion between electrons is found to be able to induce
singularities of such scattering at zero temperature as in one-dimensional
conductors. In striking contrast to electrons in one space dimension, however,
repulsive interactions here can enhance transport. We present explicit
calculations for the scattering from vector potentials that appear when strips
of the material are under strain. There the predicted effects are exponentially
large for strong scatterers.Comment: 4 pages, 2 figure
From GM Law to A Powerful Mean Field Scheme
A new and powerful mean field scheme is presented. It maps to a
one-dimensional finite closed chain in an external field. The chain size
accounts for lattice topologies. Moreover lattice connectivity is rescaled
according to the GM law recently obtained in percolation theory. The associated
self-consistent mean-field equation of state yields critical temperatures which
are within a few percent of exact estimates. Results are obtained for a large
variety of lattices and dimensions. The Ising lower critical dimension for the
onset of phase transitions is . For the Ising hypercube it
becomes the Golden number . The scheme recovers the
exact result of no long range order for non-zero temperature Ising triangular
antiferromagnets.Comment: 3M Conference Proceedings, San Jose, California (November, 1999
Quantum critical phenomena of long-range interacting bosons in a time-dependent random potential
We study the superfluid-insulator transition of a particle-hole symmetric
system of long-range interacting bosons in a time-dependent random potential in
two dimensions, using the momentum-shell renormalization-group method. We find
a new stable fixed point with non-zero values of the parameters representing
the short- and long-range interactions and disorder when the interaction is
asymptotically logarithmic. This is contrasted to the non-random case with a
logarithmic interaction, where the transition is argued to be first-order, and
to the Coulomb interaction case, where either a first-order transition or
an XY-like transition is possible depending on the parameters. We propose that
our model may be relevant in studying the vortex liquid-vortex glass transition
of interacting vortex lines in point-disordered type-II superconductors.Comment: 10 pages, 3 figure
The tunneling conductance between a superconducting STM tip and an out-of-equilibrium carbon nanotube
We calculate the current and differential conductance for the junction
between a superconducting (SC) STM tip and a Luttinger liquid (LL). For an
infinite single-channel LL, the SC coherence peaks are preserved in the
tunneling conductance for interactions weaker than a critical value, while for
strong interactions (g <0.38), they disappear and are replaced by cusp-like
features. For a finite-size wire in contact with non-interacting leads, we find
however that the peaks are restored even for extremely strong interactions. In
the presence of a source-drain voltage the peaks/cusps split, and the split is
equal to the voltage. At zero temperature, even very strong interactions do not
smear the two peaks into a broader one; this implies that the recent
experiments of Y.-F. Chen et. al. (Phys. Rev. Lett. 102, 036804 (2009)) do not
rule out the existence of strong interactions in carbon nanotubes.Comment: 8 pages, 3 figure
Interacting topological phases in multiband nanowires
We show that semiconductor nanowires coupled to an s-wave superconductor
provide a playground to study effects of interactions between different
topological superconducting phases supporting Majorana zero-energy modes. We
consider quasi-one dimensional system where the topological phases emerge from
different transverse subbands in the nanowire. In a certain parameter space, we
show that there is a multicritical point in the phase diagram where the
low-energy theory is equivalent to the one describing two coupled Majorana
chains. We study effect of interactions as well as symmetry-breaking
perturbations on the topological phase diagram in the vicinity of this
multicritical point. Our results shed light on the stability of the topological
phase around the multicritical point and have important implications for the
experiments on Majorana nanowires.Comment: 8 pages, 2 figures; final version to appear in PR
Solvation force for long ranged wall-fluid potentials
The solvation force of a simple fluid confined between identical planar walls
is studied in two model systems with short ranged fluid-fluid interactions and
long ranged wall-fluid potentials decaying as , for
various values of . Results for the Ising spins system are obtained in two
dimensions at vanishing bulk magnetic field by means of the
density-matrix renormalization-group method; results for the truncated
Lennard-Jones (LJ) fluid are obtained within the nonlocal density functional
theory. At low temperatures the solvation force for the Ising film
is repulsive and decays for large wall separations in the same fashion as
the boundary field , whereas for temperatures larger than
the bulk critical temperature is attractive and the asymptotic decay
is . For the LJ fluid system is always
repulsive away from the critical region and decays for large with the the
same power law as the wall-fluid potential. We discuss the influence of the
critical Casimir effect and of capillary condensation on the behaviour of the
solvation force.Comment: 48 pages, 12 figure
Signatures of spin-charge separation in scanning probe microscopy
We analyze the effect of an auxiliary scatterer, such as the potential of a
scanning tip, on the conductance of an interacting one-dimensional electron
system. We find that the differential conductance for tunneling into the end of
a semi-infinite quantum wire reflects the separation of the elementary
excitations into spin and charge modes. The separation is revealed as a
specific pattern in the dependence of the conductance on bias and on the
position of the scatterer.Comment: 4 pages, 1 figure; published versio
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