7,067 research outputs found
The ground state of a class of noncritical 1D quantum spin systems can be approximated efficiently
We study families H_n of 1D quantum spin systems, where n is the number of
spins, which have a spectral gap \Delta E between the ground-state and
first-excited state energy that scales, asymptotically, as a constant in n. We
show that if the ground state |\Omega_m> of the hamiltonian H_m on m spins,
where m is an O(1) constant, is locally the same as the ground state
|\Omega_n>, for arbitrarily large n, then an arbitrarily good approximation to
the ground state of H_n can be stored efficiently for all n. We formulate a
conjecture that, if true, would imply our result applies to all noncritical 1D
spin systems. We also include an appendix on quasi-adiabatic evolutions.Comment: 9 pages, 1 eps figure, minor change
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Sample size and subject to item ratio in principal components analysis
Statisticians have wrestled with the question of sample size in exploratory factor analysis and principal component analysis for decades, some looking at total N, some at the ratio of subjects to items. Although many articles attempt to examine this issue, few examine both possibilities comprehensively enough to be definitive. This study examines a previously published data set to examine whether N or subject to item ratio is more important in predicting important outcomes in PCA. The results indicate an interaction between the two, where the best outcomes occur in analyses where large Ns and high ratios are present. Accessed 116,372 times on https://pareonline.net from June 07, 2004 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right
Achievable Qubit Rates for Quantum Information Wires
Suppose Alice and Bob have access to two separated regions, respectively, of
a system of electrons moving in the presence of a regular one-dimensional
lattice of binding atoms. We consider the problem of communicating as much
quantum information, as measured by the qubit rate, through this quantum
information wire as possible. We describe a protocol whereby Alice and Bob can
achieve a qubit rate for these systems which is proportional to N^(-1/3) qubits
per unit time, where N is the number of lattice sites. Our protocol also
functions equally in the presence of interactions modelled via the t-J and
Hubbard models
Quasi-Adiabatic Continuation in Gapped Spin and Fermion Systems: Goldstone's Theorem and Flux Periodicity
We apply the technique of quasi-adiabatic continuation to study systems with
continuous symmetries. We first derive a general form of Goldstone's theorem
applicable to gapped nonrelativistic systems with continuous symmetries. We
then show that for a fermionic system with a spin gap, it is possible to insert
-flux into a cylinder with only exponentially small change in the energy
of the system, a scenario which covers several physically interesting cases
such as an s-wave superconductor or a resonating valence bond state.Comment: 19 pages, 2 figures, final version in press at JSTA
The Mechanism Of Hydrotrope Action Of A Dicarboxylic Acid
The mechanism of the hydro trope action of a dicarboxylic acid Mono soap was investigated by determination of the change in order parameter of the amphiphile in a lamellar liquid crystal. The results showed addition of the hydro trope considerably to reduce the order while addition of a surfactant had no effect. © 1986
Relation between concurrence and Berry phase of an entangled state of two spin 1/2 particles
We have studied here the influence of the Berry phase generated due to a
cyclic evolution of an entangled state of two spin 1/2 particles. It is shown
that the measure of formation of entanglement is related to the cyclic
geometric phase of the individual spins. \\Comment: 6 pages. Accepted in Europhys. Letters (likely to be published in vol
73, pp1-6 (2006)
A-STAR: The All-Sky Transient Astrophysics Reporter
The small mission A-STAR (All-Sky Transient Astrophysics Reporter) aims to
locate the X-ray counterparts to ALIGO and other gravitational wave detector
sources, to study the poorly-understood low luminosity gamma-ray bursts, and to
find a wide variety of transient high-energy source types, A-STAR will survey
the entire available sky twice per 24 hours. The payload consists of a coded
mask instrument, Owl, operating in the novel low energy band 4-150 keV, and a
sensitive wide-field focussing soft X-ray instrument, Lobster, working over
0.15-5 keV. A-STAR will trigger on ~100 GRBs/yr, rapidly distributing their
locations.Comment: Accepted for the European Astronomical Society Publications Series:
Proceedings of the Fall 2012 Gamma-Ray Burst Symposium held in Marbella,
Spain, 8-12 Oct 201
Space tug propulsion system failure mode, effects and criticality analysis
For purposes of the study, the propulsion system was considered as consisting of the following: (1) main engine system, (2) auxiliary propulsion system, (3) pneumatic system, (4) hydrogen feed, fill, drain and vent system, (5) oxygen feed, fill, drain and vent system, and (6) helium reentry purge system. Each component was critically examined to identify possible failure modes and the subsequent effect on mission success. Each space tug mission consists of three phases: launch to separation from shuttle, separation to redocking, and redocking to landing. The analysis considered the results of failure of a component during each phase of the mission. After the failure modes of each component were tabulated, those components whose failure would result in possible or certain loss of mission or inability to return the Tug to ground were identified as critical components and a criticality number determined for each. The criticality number of a component denotes the number of mission failures in one million missions due to the loss of that component. A total of 68 components were identified as critical with criticality numbers ranging from 1 to 2990
Gestation and Lactation Rations for Ewes
The purpose of this study is to determine wether these two forms of haylage are satisfactory both nutritionally and economically in the lactation as well as the gestation period
Stability of Coalescence Hidden variable Fractal Interpolation Surfaces
In the present paper, the stability of Coalescence Hidden variable Fractal
Interpolation Surfaces(CHFIS) is established. The estimates on error in
approximation of the data generating function by CHFIS are found when there is
a perturbation in independent, dependent and hidden variables. It is proved
that any small perturbation in any of the variables of generalized
interpolation data results in only small perturbation of CHFIS. Our results are
likely to be useful in investigations of texture of surfaces arising from the
simulation of surfaces of rocks, sea surfaces, clouds and similar natural
objects wherein the generating function depends on more than one variable
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