2,652 research outputs found
Topological quantum phase transition and the Berry phase near the Fermi surface in hole-doped quantum wells
We propose a topological quantum phase transition for quantum states with
different Berry phases in hole-doped III-V semiconductor quantum wells with
bulk and structure inversion asymmetry. The Berry phase of the occupied Bloch
states can be characteristic of topological metallic states. It is found that
the adjustment of thickness of the quantum well may cause a transition of Berry
phase in two-dimensional hole gas. Correspondingly, the jump of spin Hall
conductivity accompanies the change of the Berry phase. This property is robust
against the impurity potentials in the system. Experimental detection of this
topological quantum phase transition is discussed
Thermodynamic of the Ghost Dark Energy Universe
Recently, the vacuum energy of the QCD ghost in a time-dependent background
is proposed as a kind of dark energy candidate to explain the acceleration of
the Universe. In this model, the energy density of the dark energy is
proportional to the Hubble parameter , which is the Hawking temperature on
the Hubble horizon of the Friedmann-Robertson-Walker (FRW) Universe. In this
paper, we generalized this model and choice the Hawking temperature on the
so-called trapping horizon, which will coincides with the Hubble temperature in
the context of flat FRW Universe dominated by the dark energy component. We
study the thermodynamics of Universe with this kind of dark energy and find
that the entropy-area relation is modified, namely, there is an another new
term besides the area term.Comment: 8 pages, no figure
EvIcon: Designing High-Usability Icon with Human-in-the-loop Exploration and IconCLIP
Interface icons are prevalent in various digital applications. Due to limited
time and budgets, many designers rely on informal evaluation, which often
results in poor usability icons. In this paper, we propose a unique
human-in-the-loop framework that allows our target users, i.e., novice and
professional UI designers, to improve the usability of interface icons
efficiently. We formulate several usability criteria into a perceptual
usability function and enable users to iteratively revise an icon set with an
interactive design tool, EvIcon. We take a large-scale pre-trained joint
image-text embedding (CLIP) and fine-tune it to embed icon visuals with icon
tags in the same embedding space (IconCLIP). During the revision process, our
design tool provides two types of instant perceptual usability feedback. First,
we provide perceptual usability feedback modeled by deep learning models
trained on IconCLIP embeddings and crowdsourced perceptual ratings. Second, we
use the embedding space of IconCLIP to assist users in improving icons' visual
distinguishability among icons within the user-prepared icon set. To provide
the perceptual prediction, we compiled IconCEPT10K, the first large-scale
dataset of perceptual usability ratings over interface icons, by
conducting a crowdsourcing study. We demonstrated that our framework could
benefit UI designers' interface icon revision process with a wide range of
professional experience. Moreover, the interface icons designed using our
framework achieved better semantic distance and familiarity, verified by an
additional online user study
Current-induced Spin Polarization in Two-Dimensional Hole Gas
We investigate the current-induced spin polarization in the two-dimensional
hole gas (2DHG) with the structure inversion asymmetry. By using the
perturbation theory, we re-derive the effective -cubic Rashba Hamiltonian
for 2DHG and the generalized spin operators accordingly. Then based on the
linear response theory we calculate the current-induced spin polarization both
analytically and numerically with the disorder effect considered. We have found
that, quite different from the two-dimensional electron gas, the spin
polarization in 2DHG depends linearly on Fermi energy in the low doping regime,
and with increasing Fermi energy, the spin polarization may be suppressed and
even changes its sign. We predict a pronounced peak of the spin polarization in
2DHG once the Fermi level is somewhere between minimum points of two spin-split
branches of the lowest light-hole subband. We discuss the possibility of
measurements in experiments as regards the temperature and the width of quantum
wells.Comment: 13 pages, 8 figures, submitted to PR
- …