24,637 research outputs found
Reading-out the state of a flux qubit by Josephson transmission line solitons
We describe the read-out process of the state of a Josephson flux qubit via
solitons in Josephson transmission lines (JTL) as they are in use in the
standard rapid single flux quantum (RSFQ) technology. We consider the situation
where the information about the state of the qubit is stored in the time delay
of the soliton. We analyze dissipative underdamped JTLs, take into account
their jitter, and provide estimates of the measuring time and efficiency of the
measurement for relevant experimental parameters.Comment: 13 pages, 12 figure
Scar Intensity Statistics in the Position Representation
We obtain general predictions for the distribution of wave function
intensities in position space on the periodic orbits of chaotic ballistic
systems. The expressions depend on effective system size N, instability
exponent lambda of the periodic orbit, and proximity to a focal point of the
orbit. Limiting expressions are obtained that include the asymptotic
probability distribution of rare high-intensity events and a perturbative
formula valid in the limit of weak scarring. For finite system sizes, a single
scaling variable lambda N describes deviations from the semiclassical N ->
infinity limit.Comment: To appear in Phys. Rev. E, 10 pages, including 4 figure
Wave Function Structure in Two-Body Random Matrix Ensembles
We study the structure of eigenstates in two-body interaction random matrix
ensembles and find significant deviations from random matrix theory
expectations. The deviations are most prominent in the tails of the spectral
density and indicate localization of the eigenstates in Fock space. Using ideas
related to scar theory we derive an analytical formula that relates
fluctuations in wave function intensities to fluctuations of the two-body
interaction matrix elements. Numerical results for many-body fermion systems
agree well with the theoretical predictions.Comment: 4 pages, 2 figure
Kaon Condensation and Dynamical Nucleons in Neutron Stars
We discuss the nature of the kaon condensation phase transition. We find
several features which, if kaons condense in neutron stars, are not only
remarkable, but must surely effect such properties as superfluidity and
transport properties, which in turn are relevant to the glitch phenomenon and
cooling rates of neutron stars. The mixed phase, because of the extensive
pressure range that it spans, will occupy a broad radial extent in a neutron
star. This region is permeated with microscopic drops (and other
configurations) located at lattice sites of one phase immersed in the
background of the other phase. The electric charge on drops is opposite to that
of the background phase {\sl and} nucleons have a mass approximately a factor
two different depending on whether they are in the drops or the background
phase. A large part of the stellar interior has this highly non-homogeneous
structure.Comment: 5 pages, 6 figures, revtex. Physical Review Letters (accepted
Energy Extraction From Gravitational Collapse to Static Black Holes
The mass--energy formula of black holes implies that up to 50% of the energy
can be extracted from a static black hole. Such a result is reexamined using
the recently established analytic formulas for the collapse of a shell and
expression for the irreducible mass of a static black hole. It is shown that
the efficiency of energy extraction process during the formation of the black
hole is linked in an essential way to the gravitational binding energy, the
formation of the horizon and the reduction of the kinetic energy of implosion.
Here a maximum efficiency of 50% in the extraction of the mass energy is shown
to be generally attainable in the collapse of a spherically symmetric shell:
surprisingly this result holds as well in the two limiting cases of the
Schwarzschild and extreme Reissner-Nordstr\"{o}m space-times. Moreover, the
analytic expression recently found for the implosion of a spherical shell onto
an already formed black hole leads to a new exact analytic expression for the
energy extraction which results in an efficiency strictly less than 100% for
any physical implementable process. There appears to be no incompatibility
between General Relativity and Thermodynamics at this classical level.Comment: 7 pages, 2 figures, to appear on Int. Journ. Mod. Phys.
Constraining recent lead pollution sources in the North Pacific using ice core stable lead isotopes
Trends and sources of lead (Pb) aerosol pollution in the North Pacific rim of North America from 1850 to 2001 are investigated using a high-resolution (subannual to annual) ice core record recovered from Eclipse Icefield (3017 masl; St. Elias Mountains, Canada). Beginning in the early 1940s, increasing Pb concentration at Eclipse Icefield occurs coevally with anthropogenic Pb deposition in central Greenland, suggesting that North American Pb pollution may have been in part or wholly responsible in both regions. Isotopic ratios (208Pb/207Pb and 206Pb/207Pb) from 1970 to 2001 confirm that a portion of the Pb deposited at Eclipse Icefield is anthropogenic, and that it represents a variable mixture of East Asian (Chinese and Japanese) emissions transported eastward across the Pacific Ocean and a North American component resulting from transient meridional atmospheric flow. Based on comparison with source material Pb isotope ratios, Chinese and North American coal combustion have likely been the primary sources of Eclipse Icefield Pb over the 1970–2001 time period. The Eclipse Icefield Pb isotope composition also implies that the North Pacific mid-troposphere is not directly impacted by transpolar atmospheric flow from Europe. Annually averaged Pb concentrations in the Eclipse Icefield ice core record show no long-term trend during 1970–2001; however, increasing 208Pb/207Pb and decreasing 206Pb/207Pb ratios reflect the progressive East Asian industrialization and increase in Asian pollutant outflow. The post-1970 decrease in North American Pb emissions is likely necessary to explain the Eclipse Icefield Pb concentration time series. When compared with low (lichen) and high (Mt. Logan ice core) elevation Pb data, the Eclipse ice core record suggests a gradual increase in pollutant deposition and stronger trans-Pacific Asian contribution with rising elevation in the mountains of the North Pacific rim
The Long and Short of Nuclear Effective Field Theory Expansions
Nonperturbative effective field theory calculations for NN scattering seem to
break down at rather low momenta. By examining several toy models, we clarify
how effective field theory expansions can in general be used to properly
separate long- and short-range effects. We find that one-pion exchange has a
large effect on the scattering phase shift near poles in the amplitude, but
otherwise can be treated perturbatively. Analysis of a toy model that
reproduces 1S0 NN scattering data rather well suggests that failures of
effective field theories for momenta above the pion mass can be due to
short-range physics rather than the treatment of pion exchange. We discuss the
implications this has for extending the applicability of effective field
theories.Comment: 22 pages, 9 figures, references corrected, minor modification
Gap Domain Wall Fermions
I demonstrate that the chiral properties of Domain Wall Fermions (DWF) in the
large to intermediate lattice spacing regime of QCD, 1 to 2 GeV, are
significantly improved by adding to the action two standard Wilson fermions
with supercritical mass equal to the negative DWF five dimensional mass. Using
quenched DWF simulations I show that the eigenvalue spectrum of the transfer
matrix Hamiltonian develops a substantial gap and that the residual mass
decreases appreciatively. Furthermore, I confirm that topology changing remains
active and that the hadron spectrum of the added Wilson fermions is above the
lattice cutoff and therefore is irrelevant. I argue that this result should
also hold for dynamical DWF and furthermore that it should improve the chiral
properties of related fermion methods.Comment: 12 pages of text, 14 figures, added sect.6 on topology and reference
Neutrino-nucleus interaction rates at a low-energy beta-beam facility
We compute the neutrino detection rates to be expected at a low-energy
beta-beam facility. We consider various nuclei as neutrino detectors and
compare the case of a small versus large storage ring.Comment: 6 pages, 3 figure
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