3,518 research outputs found
Entanglement distribution over the subsystems and its invariance
We study the entanglement dynamics of two qubits, each of which is embedded
into its local amplitude-damping reservoir, and the entanglement distribution
among all the bipartite subsystems including qubit-qubit, qubit-reservoir, and
reservoir-reservoir. It is found that the entanglement can be stably
distributed among all components, which is much different to the result
obtained under the Born-Markovian approximation by C. E. L\'{o}pez {\it et al.}
[Phys. Rev. Lett. \textbf{101}, 080503 (2008)], and particularly it also
satisfies an identity. Our unified treatment includes the previous results as
special cases. The result may give help to understand the physical nature of
entanglement under decoherence.Comment: 6 pages, 5 figure
Generating Many Majorana Modes via Periodic Driving: A Superconductor Model
Realizing Majorana modes (MMs) in condensed-matter systems is of vast
experimental and theoretical interests, and some signatures of MMs have been
measured already. To facilitate future experimental observations and to explore
further applications of MMs, generating many MMs at ease in an experimentally
accessible manner has become one important issue. This task is achieved here in
a one-dimensional -wave superconductor system with the nearest- and
next-nearest-neighbor interactions. In particular, a periodic modulation of
some system parameters can induce an effective long-range interaction (as
suggested by the Baker-Campbell-Hausdorff formula) and may recover
time-reversal symmetry already broken in undriven cases. By exploiting these
two independent mechanisms at once we have established a general method in
generating many Floquet MMs via periodic driving.Comment: 5 pages, 3 figures. To appear in Phys. Rev. B as a Rapid
Communicatio
The role of DSM + C to facilitate the integration of renewable energy and low carbon energy technologies
Recent legislation and building regulations have aiming to reduce the energy demands of buildings and include renewable based micro-generation technologies. Due to the variations in energy delivery from these technologies, optimised control over building plant and loads is essential if we are to achieve a good demand-supply match and achieve a reduction in energy demands. This paper reports on research being undertaken as part of the UK EPSRC SuperGen Future Networks programme, specifically relating to the development of algorithms for simulating dynamic demand side control strategies to identify demand-supply matching options when deploying building integrated renewable energy and low carbon technologies. The development of demand side management and control (DSM+c) is a means to improve the dynamic demand-supply match taking account of the available demand side management capacity and time of occurrence. The principle of the developed DSM+c algorithms is to maximise the available control capacity which will enable a better demand-supply match while minimising any impact on users. This paper will demonstrate the application of DSM+c to improve the energy efficiency of a building (e.g. reduced total capacity), restructure the demand pattern via load shifting and switching (e.g. on/off or proportional control) to one more favourable to building integrated renewables. The impact of different control strategies on demand profile restructuring will be demonstrated using simulation to alter the settings of the DSM+c parameters - such as priority, methods and periods - for a given demand profile. The paper will conclude by presenting the outcomes from a case study using the decision support/design tool, MERIT where the developed DSM+c algorithms have been implemented to better facilitate the match between demand and building integrated clean energy supply technologies at the individual multi-familiy building level
Supernova Constraints on Models of Neutrino Dark Energy
In this paper we use the recently released Type Ia Supernova (SNIa) data to
constrain the interactions between the neutrinos and the dark energy scalar
fields. In the analysis we take the dark energy scalars to be either
Quintessence-like or Phantom-like. Our results show the data mildly favor a
model where the neutrinos couple to a phantom-like dark energy scalar, which
implies the equation of state of the coupled system behaves like Quintom
scenario in the sense of parameter degeneracy. We find future observations like
SNAP are potentially promising to measure the couplings between neutrino and
dark energy.Comment: Typos fixed and references updated. Version pressed in PR
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