4,378 research outputs found
Entanglement verification with finite data
Suppose an experimentalist wishes to verify that his apparatus produces
entangled quantum states. A finite amount of data cannot conclusively
demonstrate entanglement, so drawing conclusions from real-world data requires
statistical reasoning. We propose a reliable method to quantify the weight of
evidence for (or against) entanglement, based on a likelihood ratio test. Our
method is universal in that it can be applied to any sort of measurements. We
demonstrate the method by applying it to two simulated experiments on two
qubits. The first measures a single entanglement witness, while the second
performs a tomographically complete measurement.Comment: 4 pages, 3 pretty picture
Deposit Growth in the Wetting of an Angular Region with Uniform Evaporation
Solvent loss due to evaporation in a drying drop can drive capillary flows
and solute migration. The flow is controlled by the evaporation profile and the
geometry of the drop. We predict the flow and solute migration near a sharp
corner of the perimeter under the conditions of uniform evaporation. This
extends the study of Ref. 6, which considered a singular evaporation profile,
characteristic of a dry surrounding surface. We find the rate of the deposit
growth along contact lines in early and intermediate time regimes. Compared to
the dry-surface evaporation profile of Ref. 6, uniform evaporation yields more
singular deposition in the early time regime, and nearly uniform deposition
profile is obtained for a wide range of opening angles in the intermediate time
regime. Uniform evaporation also shows a more pronounced contrast between acute
opening angles and obtuse opening angles.Comment: 12 figures, submitted to Physical Review
Characteristic Angles in the Wetting of an Angular Region: Deposit Growth
As was shown in an earlier paper [1], solids dispersed in a drying drop
migrate to the (pinned) contact line. This migration is caused by outward flows
driven by the loss of the solvent due to evaporation and by geometrical
constraint that the drop maintains an equilibrium surface shape with a fixed
boundary. Here, in continuation of our earlier paper [2], we theoretically
investigate the evaporation rate, the flow field and the rate of growth of the
deposit patterns in a drop over an angular sector on a plane substrate.
Asymptotic power laws near the vertex (as distance to the vertex goes to zero)
are obtained. A hydrodynamic model of fluid flow near the singularity of the
vertex is developed and the velocity field is obtained. The rate of the deposit
growth near the contact line is found in two time regimes. The deposited mass
falls off as a weak power Gamma of distance close to the vertex and as a
stronger power Beta of distance further from the vertex. The power Gamma
depends only slightly on the opening angle Alpha and stays between roughly -1/3
and 0. The power Beta varies from -1 to 0 as the opening angle increases from 0
to 180 degrees. At a given distance from the vertex, the deposited mass grows
faster and faster with time, with the greatest increase in the growth rate
occurring at the early stages of the drying process.Comment: v1: 36 pages, 21 figures, LaTeX; submitted to Physical Review E; v2:
minor additions to Abstract and Introductio
Quantum fluctuation induced ordered phase in the Blume-Capel model
We consider the Blume-Capel model with the quantum tunneling between the
excited states. We find a magnetically ordered phase transition induced by
quantum fluctuation in a model. The model has no phase transition in the
corresponding classical case. Usually, quantum fluctuation breaks ordered phase
as in the case of the transverse field Ising model. However, in present case,
an ordered phase is induced by quantum fluctuation. Moreover, we find a phase
transition between a quantum paramagnetic phase and a classical diamagnetic
phase at zero temperature. We study the properties of the phase transition by
using a mean field approximation (MFA), and then, by a quantum Monte Carlo
method to confirm the result of the MFA.Comment: 7 pages, 6 figures, corrected some typo
Real-Time Gait Analysis Using a Single Head-Worn Inertial Measurement Unit
The background of this paper is to apply advanced real-time gait analysis to walking interventions in daily life setting. A vast of wearable devices provide gait information but not more than pedometer functions such as step counting, displacement, and velocity. This paper suggests a real-time gait analysis method based on a head-worn inertial measurement unit. A novel analysis method implements real-time detection of gait events (heel strike, toe off, and mid-stance phase) and immediately provides detailed spatiotemporal parameters. The reliability of this method was proven by a measurement with over 11 000 steps from seven participants on a 400-m outdoor track. The advanced gait analysis was conducted without any limitation of a fixed reference frame (e.g., indoor stage and infrared cameras). The mean absolute error in step-counting was 0.24%. Compared to a pedometer, additional gait parameters were obtained such as foot-ground contact time (CT) and CT ratio. The gait monitoring system can be used as real-time and long-term feedback, which is applicable in the management of the health status and on injury prevention. © 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.European Commission/H2020-FETPROACT-2014/641321/E
Structure of boson systems beyond the mean-field
We investigate systems of identical bosons with the focus on two-body
correlations. We use the hyperspherical adiabatic method and a decomposition of
the wave function in two-body amplitudes. An analytic parametrization is used
for the adiabatic effective radial potential. We discuss the structure of a
condensate for arbitrary scattering length. Stability and time scales for
various decay processes are estimated. The previously predicted Efimov-like
states are found to be very narrow. We discuss the validity conditions and
formal connections between the zero- and finite-range mean-field
approximations, Faddeev-Yakubovskii formulation, Jastrow ansatz, and the
present method. We compare numerical results from present work with mean-field
calculations and discuss qualitatively the connection with measurements.Comment: 26 pages, 6 figures, submitted to J. Phys. B. Ver. 2 is 28 pages with
modified figures and discussion
Metastability and Nucleation for the Blume-Capel Model. Different mechanisms of transition
We study metastability and nucleation for the Blume-Capel model: a
ferromagnetic nearest neighbour two-dimensional lattice system with spin
variables taking values in -1,0,+1. We consider large but finite volume, small
fixed magnetic field h and chemical potential "lambda" in the limit of zero
temperature; we analyze the first excursion from the metastable -1
configuration to the stable +1 configuration. We compute the asymptotic
behaviour of the transition time and describe the typical tube of trajectories
during the transition. We show that, unexpectedly, the mechanism of transition
changes abruptly when the line h=2*lambda is crossed.Comment: 96 pages, 44 tex-figures, 7 postscript figure
Theory of Coupled Multipole Moments Probed by X-ray Scattering in CeB
A minimal model for multipole orders in CeB shows that degeneracy of the
quadrupole order parameters and strong spin-orbit coupling lead to peculiar
temperature and magnetic-field dependences of the X-ray reflection intensity at
superlattice Bragg points. Furthermore, the intensity depends sensitively on
the surface direction. These theoretical results explain naturally recent X-ray
experiments in phases II and III of CeB. It is predicted that under weak
magnetic field perpendicular to the (111) surface, the reflection intensity
should change non-monotonically as a function of temperature.Comment: 4 pages, 5 figure
Switching dynamics between metastable ordered magnetic state and nonmagnetic ground state - A possible mechanism for photoinduced ferromagnetism -
By studying the dynamics of the metastable magnetization of a statistical
mechanical model we propose a switching mechanism of photoinduced
magnetization. The equilibrium and nonequilibrium properties of the Blume-Capel
(BC) model, which is a typical model exhibiting metastability, are studied by
mean field theory and Monte Carlo simulation. We demonstrate reversible changes
of magnetization in a sequence of changes of system parameters, which would
model the reversible photoinduced magnetization. Implications of the calculated
results are discussed in relation to the recent experimental results for
prussian blue analogs.Comment: 12 pages, 13 figure
- …