1,082 research outputs found
Ergodicity from Nonergodicity in Quantum Correlations of Low-dimensional Spin Systems
Correlations between the parts of a many-body system, and its time dynamics,
lie at the heart of sciences, and they can be classical as well as quantum.
Quantum correlations are traditionally viewed as constituted out of classical
correlations and magnetizations. While that of course remains so, we show that
quantum correlations can have statistical mechanical properties like
ergodicity, which is not inherited from the corresponding classical
correlations and magnetizations, for the transverse anisotropic quantum XY
model in one-, two-, and quasi two-dimension, for suitably chosen transverse
fields and temperatures. The results have the potential for applications in
decoherence effects in realizable quantum computers.Comment: 8 pages, 6 figures, RevTeX 4.
Development and study of waterproof breathable fabric using silicone oil and polyurethane binder
The focus of this study is on determining the optimum combination of hydrophilic and hydrophobic components in coating material to obtain high breathability and waterproof properties. Polyurethane binder and silicone oil were used in eight different combinations to coat the fabric along with one sample with 100% polyurethane binder for control. A knife-over-roll coating machine was used to coat the fabric. The coated samples were tested by using the Sweating Guarded Hot Plate method for breathability and the spray test and contact angle method for waterproof properties. Results obtained from the tests showed that fabric coated with an 80%-20% and 85%-15% polyurethane-silicone oil combination displayed best performance in terms of waterproof and breathable properties. The research also concludes that with a decrease in percentage of silicone in the material, there is an increase in breathability as well as waterproof properties of fabric, and best performance is achieved when its percentage is between 20 and 25%
Detection of Sand Boils from Images using Machine Learning Approaches
Levees provide protection for vast amounts of commercial and residential properties. However, these structures degrade over time, due to the impact of severe weather, sand boils, subsidence of land, seepage, etc. In this research, we focus on detecting sand boils. Sand boils occur when water under pressure wells up to the surface through a bed of sand. These make levees especially vulnerable. Object detection is a good approach to confirm the presence of sand boils from satellite or drone imagery, which can be utilized to assist in the automated levee monitoring methodology. Since sand boils have distinct features, applying object detection algorithms to it can result in accurate detection. To the best of our knowledge, this research work is the first approach to detect sand boils from images. In this research, we compare some of the latest deep learning methods, Viola Jones algorithm, and other non-deep learning methods to determine the best performing one. We also train a Stacking-based machine learning method for the accurate prediction of sand boils. The accuracy of our robust model is 95.4%
Local indistinguishability: more nonlocality with less entanglement
We provide a first operational method for checking indistinguishability of
orthogonal states by local operations and classical communication (LOCC). This
method originates from the one introduced by Ghosh et al. (Phys. Rev. Lett. 87,
5807 (2001) (quant-ph/0106148)), though we deal with pure states. We apply our
method to show that an arbitrary complete multipartite orthogonal basis is
indistinguishable by LOCC, if it contains at least one entangled state. We also
show that probabilistic local distinguishing is possible for full basis if and
only if all vectors are product. We employ our method to prove local
indistinguishability in an example with sets of pure states of 3X3, which shows
that one can have ``more nonlocality with less entanglement'', where ``more
nonlocality'' is in the sense of ``increased local indistinguishability of
orthogonal states''. This example also provides, to our knowledge, the only
known example where d orthogonal states in dXd are locally indistinguishable.Comment: 4 pages, no figures, RevTeX4, partially supersedes quant-ph/0204116,
to appear in Phys. Rev. Let
Current driven quantum criticality in itinerant electron ferromagnets
We determine the effect of an in-plane current flow on the critical
properties of a 2d itinerant electron system near a ferromagnetic-paramagnetic
quantum critical point. We study a model in which a nonequilibrium steady state
is established as a result of exchange of particles and energy with an
underlying substrate. the current gives rise not only to an effective
temperature equal to the voltage drop over a distance of order the mean free
path, but also to symmetry breaking terms of the form in the effective action. The effect of the symmetry breaking on
the fluctuational and critical properties is found to be small although (in
agreement with previous results) if rotational degrees of freedom are
important, the current can make the classically ordered state dynamically
unstable.Comment: 4 pages, published versio
Convergence of Gibbs Sampling: Coordinate Hit-And-Run Mixes Fast
The Gibbs Sampler is a general method for sampling high-dimensional distributions, dating back to 1971. In each step of the Gibbs Sampler, we pick a random coordinate and re-sample that coordinate from the distribution induced by fixing all the other coordinates. While it has become widely used over the past half-century, guarantees of efficient convergence have been elusive. We show that for a convex body K in ?? with diameter D, the mixing time of the Coordinate Hit-and-Run (CHAR) algorithm on K is polynomial in n and D. We also give a lower bound on the mixing rate of CHAR, showing that it is strictly worse than hit-and-run and the ball walk in the worst case
Monogamy of quantum correlations reveals frustration in a quantum Ising spin system: Experimental demonstration
We report a nuclear magnetic resonance experiment, which simulates the
quantum transverse Ising spin system in a triangular configuration and further
show that the monogamy of quantum correlations can be used to distinguish
between the frustrated and non-frustrated regimes in the ground state of this
system. Adiabatic state preparation methods are used to prepare the ground
states of the spin system. We employ two different multipartite quantum
correlation measures to analyze the experimental ground state of the system in
both the frustrated and non-frustrated regimes. In particular, we use
multipartite quantum correlation measures generated by monogamy considerations
of negativity, a bipartite entanglement measure, and that of quantum discord,
an information-theoretic quantum correlation measure. As expected from
theoretical predictions, the experimental data confirm that the non-frustrated
regime shows higher multipartite quantum correlations compared to the
frustrated one.Comment: Title in the published version is "Multipartite quantum correlations
reveal frustration in a quantum Ising spin system", 7 pages, 4 figure
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