13,401 research outputs found
Spin filtering implemented through Rashba and weak magnetic modulations
We present two theoretical schemes for spin filters in one-dimensional
semiconductor quantum wires with spatially modulated Rashba spin-orbit coupling
(SOC) as well as weak magnetic potential. For case I, the SOC is periodic and
the weak magnetic potential is applied uniformly along the wire. Full spin
polarizations with opposite signs are obtained within two separated energy
intervals. For case II, the weak magnetic potential is periodic while the SOC
is uniform. An ideal negative/positive switching effect for spin polarization
is realized by tuning the strength of SOC. The roles of SOC, magnetic
potential, and their coupling on the spin filtering are analyzed.Comment: 4 pages, 4 figure
Efficient Scheme for Perfect Collective Einstein-Podolsky-Rosen Steering
A practical scheme for the demonstration of perfect one-sided
device-independent quantum secret sharing is proposed. The scheme involves a
three-mode optomechanical system in which a pair of independent cavity modes is
driven by short laser pulses and interact with a movable mirror. We demonstrate
that by tuning the laser frequency to the blue (anti-Stokes) sideband of the
average frequency of the cavity modes, the modes become mutually coherent and
then may collectively steer the mirror mode to a perfect
Einstein-Podolsky-Rosen state. The scheme is shown to be experimentally
feasible, it is robust against the frequency difference between the modes,
mechanical thermal noise and damping, and coupling strengths of the cavity
modes to the mirror.Comment: 9 pages, 4 figure
Extended Holographic dark energy
The idea of relating the infrared and ultraviolet cutoffs is applied to
Brans-Dicke theory of gravitation. We find that extended holographic dark
energy from the Hubble scale or the particle horizon as the infrared cutoff
will not give accelerating expansion. The dynamical cosmological constant with
the event horizon as the infrared cutoff is a viable dark energy model.Comment: one reference is corrected, 3 pages, no figure,V3: minor correction
Trip down memory lane : revisiting red classics as television drama in post - Mao China
University of Technology, Sydney. Faculty of Arts and Social Sciences.In the post-Mao era, the boundaries of the Red Classics, the canonical Chinese socialist literary and theatrical works, and the values and aesthetics they promoted were transgressed. By adopting the “circuit of cultures” as a methodology, this thesis explicates how a canonical body of texts created to politicise and educate socialist citizens has been transformed into TV dramas appealing to an increasingly sophisticated, demanding audience. The study situates the transformation of the genre within the context of China’s transition from a Maoist socialist society to a neoliberal one. The TV adaptation of the Red Classics embodies the transition from an era dominated by mass production and consumption for ideological control to an era in which political indoctrination and market differentiation compete for audiences in contemporary China. In this process, the norms and standards prescribed by the Red
Classics have been dismantled, subverted, transgressed, and re-written
Strong energy enhancement in a laser-driven plasma-based accelerator through stochastic friction
Conventionally, friction is understood as an efficient dissipation mechanism
depleting a physical system of energy as an unavoidable feature of any
realistic device involving moving parts, e.g., in mechanical brakes. In this
work, we demonstrate that this intuitive picture loses validity in nonlinear
quantum electrodynamics, exemplified in a scenario where spatially random
friction counter-intuitively results in a highly directional energy flow. This
peculiar behavior is caused by radiation friction, i.e., the energy loss of an
accelerated charge due to the emission of radiation. We demonstrate
analytically and numerically how radiation friction can enhance the performance
of a specific class of laser-driven particle accelerators. We find the
unexpected directional energy boost to be due to the particles' energy being
reduced through friction whence the driving laser can accelerate them more
efficiently. In a quantitative case we find the energy of the laser-accelerated
particles to be enhanced by orders of magnitude.Comment: 14 pages, 3 figure
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