24,507 research outputs found
A Unified and Complete Construction of All Finite Dimensional Irreducible Representations of gl(2|2)
Representations of the non-semisimple superalgebra in the standard
basis are investigated by means of the vector coherent state method and
boson-fermion realization. All finite-dimensional irreducible typical and
atypical representations and lowest weight (indecomposable) Kac modules of
are constructed explicitly through the explicit construction of all
particle states (multiplets) in terms of boson and fermion
creation operators in the super-Fock space. This gives a unified and complete
treatment of finite-dimensional representations of in explicit form,
essential for the construction of primary fields of the corresponding current
superalgebra at arbitrary level.Comment: LaTex file, 23 pages, two references and a comment added, to appear
in J. Math. Phy
Time-reversal-symmetry-broken quantum spin Hall effect
Quantum spin Hall (QSH) state of matter is usually considered to be protected
by time-reversal (TR) symmetry. We investigate the fate of the QSH effect in
the presence of the Rashba spin-orbit coupling and an exchange field, which
break both inversion and TR symmetries. It is found that the QSH state
characterized by nonzero spin Chern numbers persists when the
TR symmetry is broken. A topological phase transition from the TR
symmetry-broken QSH phase to a quantum anomalous Hall phase occurs at a
critical exchange field, where the bulk band gap just closes. It is also shown
that the transition from the TR symmetry-broken QSH phase to an ordinary
insulator state can not happen without closing the band gap.Comment: 5 pages, 5 figure
A Flexible Privacy-preserving Framework for Singular Value Decomposition under Internet of Things Environment
The singular value decomposition (SVD) is a widely used matrix factorization
tool which underlies plenty of useful applications, e.g. recommendation system,
abnormal detection and data compression. Under the environment of emerging
Internet of Things (IoT), there would be an increasing demand for data analysis
to better human's lives and create new economic growth points. Moreover, due to
the large scope of IoT, most of the data analysis work should be done in the
network edge, i.e. handled by fog computing. However, the devices which provide
fog computing may not be trustable while the data privacy is often the
significant concern of the IoT application users. Thus, when performing SVD for
data analysis purpose, the privacy of user data should be preserved. Based on
the above reasons, in this paper, we propose a privacy-preserving fog computing
framework for SVD computation. The security and performance analysis shows the
practicability of the proposed framework. Furthermore, since different
applications may utilize the result of SVD operation in different ways, three
applications with different objectives are introduced to show how the framework
could flexibly achieve the purposes of different applications, which indicates
the flexibility of the design.Comment: 24 pages, 4 figure
Suppression of dephasing by qubit motion in superconducting circuits
We suggest and demonstrate a protocol which suppresses dephasing due to the
low-frequency noise by qubit motion, i.e., transfer of the logical qubit of
information in a system of physical qubits. The protocol requires
only the nearest-neighbor coupling and is applicable to different qubit
structures. We further analyze its effectiveness against noises with arbitrary
correlations. Our analysis, together with experiments using up to three
superconducting qubits, shows that for the realistic uncorrelated noises, qubit
motion increases the dephasing time of the logical qubit as . In
general, the protocol provides a diagnostic tool to measure the noise
correlations.Comment: 5 pages with 3 embedded figures, plus supplementary informatio
Enthusiasm vs. reality: a job analysis of Chinese sport scientists
The aim of this study was to survey Chinese sport scientists to develop an understanding of their demographics, job characteristics, future career intentions, and opinions. This study adapted online survey and used convenience sampling to investigate the role of sport scientists across China. Ninety-seven practitioners across 18 provinces/municipalities participated in this study. Participants were typically married (70%), male (71%), aged between 30-39 (52%), and held a master’s degree (66%). Most participants were employed full-time (90%) by sport science institutes (66%), with a wide salary range, long working hours (≈48 hr per week) and irregular working time (40%). Most participants remained at the same institute (85%) throughout their career. The most frequent reason why sport scientists remained in their current position was “job enjoyment” (4.04/5). The most frequently reported issue encountered by participants was “opinion differences with sport coaches” (21%). The ability to “gain trust” and “communication” were deemed important in the role of a sport scientist. Approximately half (44%) of the participants were satisfied with their current position and employer, while others wanted promotion (34%) or to leave their role (11%). The results revealed that (1) China’s sport scientists are engaged in their current job mainly due to their enthusiasm, (2) their jobs are stable but highly demanding and relatively low paid. Poor working conditions and low retention are evident across Chinese sport scientist roles. Governing bodies should make efforts to improve the work conditions to improve the sustainability of sport scientist roles in the Chinese sport industry
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