4,178 research outputs found
Quasinormal modes, quantized black holes, and correspondence principle
Contrary to the wide-spread belief, the correspondence principle does not
dictate any relation between the asymptotics of quasinormal modes and the
spectrum of quantized black holes. Moreover, this belief is in conflict with
simple physical arguments.Comment: 2 pages; a new argument adde
Quantization and simulation of Born-Infeld non-linear electrodynamics on a lattice
Born-Infeld non-linear electrodynamics arises naturally as a field theory
description of the dynamics of strings and branes. Most analyses of this theory
have been limited to studying it as a classical field theory. We quantize this
theory on a Euclidean 4-dimensional space-time lattice and determine its
properties using Monte-Carlo simulations. The electromagnetic field around a
static point charge is measured using Luscher-Weisz methods to overcome the
sign problem associated with the introduction of this charge. The D field
appears identical to that of Maxwell QED. However, the E field is enhanced by
quantum fluctuations, while still showing the short distance screening observed
in the classical theory. In addition, whereas for the classical theory, the
screening increases without bound as the non-linearity increases, the quantum
theory approaches a limiting conformal field theory.Comment: 24 pages, 10 figures. Latex with postscript figure
Nonperturbative calculation of Born-Infeld effects on the Schroedinger spectrum of the hydrogen atom
We present the first nonperturbative numerical calculations of the
nonrelativistic hydrogen spectrum as predicted by first-quantized
electrodynamics with nonlinear Maxwell-Born-Infeld field equations. We also
show rigorous upper and lower bounds on the ground state.
When judged against empirical data our results significantly restrict the
range of viable values of the new electromagnetic constant which is introduced
by the Born-Infeld theory.
We assess Born's own proposal for the value of his constant.Comment: 4p., 2 figs, 1 table; submitted for publicatio
Lattice dynamics of anharmonic solids from first principles
An accurate and easily extendable method to deal with lattice dynamics of
solids is offered. It is based on first-principles molecular dynamics
simulations and provides a consistent way to extract the best possible harmonic
- or higher order - potential energy surface at finite temperatures. It is
designed to work even for strongly anharmonic systems where the traditional
quasiharmonic approximation fails. The accuracy and convergence of the method
are controlled in a straightforward way. Excellent agreement of the calculated
phonon dispersion relations at finite temperature with experimental results for
bcc Li and bcc Zr is demonstrated
Biexcitons in two-dimensional systems with spatially separated electrons and holes
The binding energy and wavefunctions of two-dimensional indirect biexcitons
are studied analytically and numerically. It is proven that stable biexcitons
exist only when the distance between electron and hole layers is smaller than a
certain critical threshold. Numerical results for the biexciton binding
energies are obtained using the stochastic variational method and compared with
the analytical asymptotics. The threshold interlayer separation and its
uncertainty are estimated. The results are compared with those obtained by
other techniques, in particular, the diffusion Monte-Carlo method and the
Born-Oppenheimer approximation.Comment: 11 pages, 7 figure
Dynamics of the Born-Infeld dyons
The approach to the dynamics of a charged particle in the Born-Infeld
nonlinear electrodynamics developed in [Phys. Lett. A 240 (1998) 8] is
generalized to include a Born-Infeld dyon. Both Hamiltonian and Lagrangian
structures of many dyons interacting with nonlinear electromagnetism are
constructed. All results are manifestly duality invariant.Comment: 11 pages, LATE
Wigner quasi-probability distribution for the infinite square well: energy eigenstates and time-dependent wave packets
We calculate the Wigner quasi-probability distribution for position and
momentum, P_W^(n)(x,p), for the energy eigenstates of the standard infinite
well potential, using both x- and p-space stationary-state solutions, as well
as visualizing the results. We then evaluate the time-dependent Wigner
distribution, P_W(x,p;t), for Gaussian wave packet solutions of this system,
illustrating both the short-term semi-classical time dependence, as well as
longer-term revival and fractional revival behavior and the structure during
the collapsed state. This tool provides an excellent way of demonstrating the
patterns of highly correlated Schrodinger-cat-like `mini-packets' which appear
at fractional multiples of the exact revival time.Comment: 45 pages, 16 embedded, low-resolution .eps figures (higher
resolution, publication quality figures are available from the authors);
submitted to American Journal of Physic
Duality Between Spatial and Angular Shift in Optical Reflection
We report a unified representation of the spatial and angular Goos-Hanchen
and Imbert-Fedorov shifts that occur when a light beam reflects from a plane
interface. We thus reveal the dual nature of spatial and angular shifts in
optical beam reflection. In the Goos-Hanchen case we show theoretically and
experimentally that this unification naturally arises in the context of
reflection from a lossy surface (e.g., a metal).Comment: 4 pages, 3 figure
Feasibility of loophole-free nonlocality tests with a single photon
Recently much interest has been directed towards designing setups that
achieve realistic loss thresholds for decisive tests of local realism, in
particular in the optical regime. We analyse the feasibility of such Bell tests
based on a W-state shared between multiple parties, which can be realised for
example by a single photon shared between spatial modes. We develop a general
error model to obtain thresholds on the efficiencies required to violate local
realism, and also consider two concrete optical measurement schemes.Comment: 8 pages, 5 figure
Quantum mechanical Carnot engine
A cyclic thermodynamic heat engine runs most efficiently if it is reversible.
Carnot constructed such a reversible heat engine by combining adiabatic and
isothermal processes for a system containing an ideal gas. Here, we present an
example of a cyclic engine based on a single quantum-mechanical particle
confined to a potential well. The efficiency of this engine is shown to equal
the Carnot efficiency because quantum dynamics is reversible. The quantum heat
engine has a cycle consisting of adiabatic and isothermal quantum processes
that are close analogues of the corresponding classical processes.Comment: 10 page
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