4,965 research outputs found
Local Entanglement and quantum phase transition in spin models
Due to the phase interference of electromagnetic wave, one can recover the
total image of one object from a small piece of holograph, which records the
interference pattern of two laser light reflected from it. Similarly, the
quantum superposition principle allows us to derive the global phase diagram of
quantum spin models by investigating a proper local measurement. In the present
paper, we study the two-site entanglement in the antifferomagnetic spin models
with both spin-1/2 and 1. We show that its behaviors reveal some important
information on the global properties and the quantum phase transition of these
systems.Comment: 6 pages, 7 figure
A New Phase Transition Related to the Black Hole's Topological Charge
The topological charge of AdS black hole is introduced in
Ref.[1,2], where a complete thermodynamic first law is obtained. In this paper,
we investigate a new phase transition related to the topological charge in
Einstein-Maxwell theory. Firstly, we derive the explicit solutions
corresponding to the divergence of specific heat and determine
the phase transition critical point. Secondly, the curve and curve
are investigated and they exhibit an interesting van der Waals system's
behavior. Critical physical quantities are also obtained which are consistent
with those derived from the specific heat analysis. Thirdly, a van der Waals
system's swallow tail behavior is observed when in the
graph. What's more, the analytic phase transition coexistence lines are
obtained by using the Maxwell equal area law and free energy analysis, the
results of which are consistent with each other.Comment: 11 pages, 5 figure
Efficient Volumetric Method of Moments for Modeling Plasmonic Thin-Film Solar Cells with Periodic Structures
Metallic nanoparticles (NPs) support localized surface plasmon resonances
(LSPRs), which enable to concentrate sunlight at the active layer of solar
cells. However, full-wave modeling of the plasmonic solar cells faces great
challenges in terms of huge computational workload and bad matrix condition. It
is tremendously difficult to accurately and efficiently simulate near-field
multiple scattering effects from plasmonic NPs embedded into solar cells. In
this work, a preconditioned volume integral equation (VIE) is proposed to model
plasmonic organic solar cells (OSCs). The diagonal block preconditioner is
applied to different material domains of the device structure. As a result,
better convergence and higher computing efficiency are achieved. Moreover, the
calculation is further accelerated by two-dimensional periodic Green's
functions. Using the proposed method, the dependences of optical absorption on
the wavelengths and incident angles are investigated. Angular responses of the
plasmonic OSCs show the super-Lambertian absorption on the plasmon resonance
but near-Lambertian absorption off the plasmon resonance. The volumetric method
of moments and explored physical understanding are of great help to investigate
the optical responses of OSCs.Comment: 11 pages, 6 figure
Attractive Interaction between Vortex and Anti-vortex in Holographic Superfluid
Annihilation process of a pair of vortices in holographic superfluid is
numerically simulated. The process is found to consist of two stages which are
amazingly separated by vortex size . The separation distance
between vortex and anti-vortex as a function of time is well fitted by , where the scaling exponent for , and
for . Then the approaching velocity and acceleration as
functions of time and as functions of separation distance are obtained. Thus
the attractive force between vortex and anti-vortex is derived as
for the first stage, and for the second stage. In the end, we explained why the
annihilation rate of vortices in turbulent superfluid system obeys the two-body
decay law when the vortex density is low.Comment: 14 pages, 5 figure
Constrained Optimization Design of an Electron Optical System
An electron optical system can be optimized using the simplex method or complex method . By these methods, the final structure of an electron optical system, for example, an extended field lens (EFL), can be searched with a criterion of minimum objective parameter (in the present case, the coefficient of spherical aberration). Because there is no constraint in the simplex method, the constrained optimization method (the complex method) described in this paper is better than the simplex method in the design of electron optical systems. In the simplex method as well as the complex method, it is not necessary to know the explicit functional relation between the objective function and the searching parameters; and the variations of aberration coefficient with respect to some machining tolerance can be easily obtained. Therefore, comparing with other optimization methods, the simplex method and complex method have significant advantage in the optimization design of electron optical systems
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