1,428 research outputs found
Cognitive Biases in Alcohol and Marijuana Users
The current study investigated the influence of marijuana and alcohol consumption and craving on a primed word stem completion (WSC) task. One hundred participants were randomly assigned to one of three prime conditions: Substance-prime, neutral-prime, and no-prime. In the substance- and neutral-prime conditions, participants were presented with a series of prime words. After a distracter task those participants who were presented with a series of prime words, all participants were given a multi-solution WSC task, which consisted of the initial two to four letters of a word for which the participants were instructed to complete with the first word that came to mind. The numbers of substance-related and neutral-prime solutions that were produced by each participant were tallied to produce a score. Participants were then further instructed to complete measures of alcohol and marijuana consumption and craving and these measures were used as covariates in a MANCOVA analysis. The primes had a significant effect on performance in the WSC task, with the substance-prime increasing the number of alcohol- and marijuana-related word solutions compared to the neutral- and no-prime conditions. Alcohol consumption significantly influenced the production of alcohol-related word solutions, but neither marijuana consumption nor craving was associated with the production of marijuana-related word solutions. These results demonstrate that both priming and past alcohol use significantly influenced performance on a WSC task, indicating the presence, at least in part, of a cognitive bias in those who use alcohol
Theory of quasi-one dimensional imbalanced Fermi gases
We present a theory for a lattice array of weakly coupled one-dimensional
ultracold attractive Fermi gases (1D `tubes') with spin imbalance, where strong
intratube quantum fluctuations invalidate mean field theory. We first construct
an effective field theory, which treats spin-charge mixing exactly, based on
the Bethe ansatz solution of the 1D single tube problem. We show that the 1D
Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state is a two-component Luttinger
liquid, and its elementary excitations are fractional states carrying both
charge and spin. We analyze the instability of the 1D FFLO state against
inter-tube tunneling by renormalization group analysis, and find that it flows
into either a polarized Fermi liquid or a FFLO superfluid, depending on the
magnitude of interaction strength and spin imbalance. We obtain the phase
diagram of the quasi-1D system and further determine the scaling of the
superfluid transition temperature with intertube coupling.Comment: new expanded version, 8 pages, updated reference
Level Statistics and Localization for Two Interacting Particles in a Random Potential
We consider two particles with a local interaction in a random potential
at a scale (the one particle localization length). A simplified
description is provided by a Gaussian matrix ensemble with a preferential
basis. We define the symmetry breaking parameter
associated to the statistical invariance under change of basis. We show that
the Wigner-Dyson rigidity of the energy levels is maintained up to an energy
. We find that when (the
inverse lifetime of the states of the preferential basis) is smaller than
(the level spacing), and when . This implies that the two-particle localization length first
increases as before eventually behaving as .Comment: 4 pages REVTEX, 4 Figures EPS, UUENCODE
Properties of the chiral spin liquid state in generalized spin ladders
We study zero temperature properties of a system of two coupled quantum spin
chains subject to fields explicitly breaking time reversal symmetry and parity.
Suitable choice of the strength of these fields gives a model soluble by Bethe
Ansatz methods which allows to determine the complete magnetic phase diagram of
the system and the asymptotics of correlation functions from the finite size
spectrum. The chiral properties of the system for both the integrable and the
nonintegrable case are studied using numerical techniques.Comment: 19 pages, 9eps figures, Late
Emergence of Quantum Ergodicity in Rough Billiards
By analytical mapping of the eigenvalue problem in rough billiards on to a
band random matrix model a new regime of Wigner ergodicity is found. There the
eigenstates are extended over the whole energy surface but have a strongly
peaked structure. The results of numerical simulations and implications for
level statistics are also discussed.Comment: revtex, 4 pages, 4 figure
Open t-J chain with boundary impurities
We study integrable boundary conditions for the supersymmetric t-J model of
correlated electrons which arise when combining static scattering potentials
with dynamical impurities carrying an internal degree of freedom. The latter
differ from the bulk sites by allowing for double occupation of the local
orbitals. The spectrum of the resulting Hamiltonians is obtained by means of
the algebraic Bethe Ansatz.Comment: LaTeX2e, 9p
Persistent currents in diffusive metallic cavities: Large values and anomalous scaling with disorder
The effect of disorder on confined metallic cavities with an Aharonov-Bohm
flux line is addressed. We find that, even deep in the diffusive regime, large
values of persistent currents may arise for a wide variety of geometries. We
present numerical results supporting an anomalous scaling law of the average
typical current with the strength of disorder , with . This is contrasted with previously
reported results obtained for cylindrical samples where a scaling has been found. Possible links to, up to date, unexplained
experimental data are finally discussed.Comment: 5 pages, 4 figure
Quantum error correction of coherent errors by randomization
A general error correction method is presented which is capable of correcting
coherent errors originating from static residual inter-qubit couplings in a
quantum computer. It is based on a randomization of static imperfections in a
many-qubit system by the repeated application of Pauli operators which change
the computational basis. This Pauli-Random-Error-Correction (PAREC)-method
eliminates coherent errors produced by static imperfections and increases
significantly the maximum time over which realistic quantum computations can be
performed reliably. Furthermore, it does not require redundancy so that all
physical qubits involved can be used for logical purposes.Comment: revtex 4 pages, 3 fig
Phase diagram of the su(8) quantum spin tube
We calculate the phase diagram of an integrable anisotropic 3-leg quantum
spin tube connected to the su(8) algebra. We find several quantum phase
transitions for antiferromagnetic rung couplings. Their locations are
calculated exactly from the Bethe Ansatz solution and we discuss the nature of
each of the different phases.Comment: 10 pages, RevTeX, 1 postscript figur
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