13,166 research outputs found
Comment on Counterintuitive consequence of heating in strongly driven intrinsic junctions of BiSrCaCuO mesas
In a recent paper [Phys.Rev.B 81, 224518 (2010)], C. Kurter et al, analyzed
the effect of strong self-heating in large-area
BiSrCaCuO (Bi-2212) mesa structures. They conclude
that conductance peaks in their mesas occur when mesas are heated to
the superconducting critical temperature . Further on they extrapolate
this statement for all mesas, including much smaller and much better thermally
anchored mesas used in Intrinsic Tunnelling Spectroscopy (ITS). Here I show
that their conclusion does not hold neither for previously reported data, nor
even for their own mesas; the very remote extrapolation to ITS is invalid. I
also point out a number of inconsistencies and misleading references.Comment: 2 page
Subthreshold characteristics of pentacene field-effect transistors influenced by grain boundaries.
Grain boundaries in polycrystalline pentacene films significantly affect the electrical characteristics of pentacene field-effect transistors (FETs). Upon reversal of the gate voltage sweep direction, pentacene FETs exhibited hysteretic behaviours in the subthreshold region, which was more pronounced for the FET having smaller pentacene grains. No shift in the flat-band voltage of the metal-insulator-semiconductor capacitor elucidates that the observed hysteresis was mainly caused by the influence of localized trap states existing at pentacene grain boundaries. From the results of continuous on/off switching operation of the pentacene FETs, hole depletion during the off period is found to be limited by pentacene grain boundaries. It is suggested that the polycrystalline nature of a pentacene film plays an important role on the dynamic characteristics of pentacene FETs
Secrecy content of two-qubit states
We analyze the set of two-qubit states from which a secret key can be
extracted by single-copy measurements plus classical processing of the
outcomes. We introduce a key distillation protocol and give the corresponding
necessary and sufficient condition for positive key extraction. Our results
imply that the critical error rate derived by Chau, Phys. Rev. A {\bf 66},
060302 (2002), for a secure key distribution using the six-state scheme is
tight. Remarkably, an optimal eavesdropping attack against this protocol does
not require any coherent quantum operation.Comment: 5 pages, RevTe
Radion Dynamics and Phenomenology in the Linear Dilaton Model
We investigate the properties of the radion in the 5D linear dilaton model
arising from Little String Theory. A Goldberger-Wise type mechanism is used to
stabilise a large interbrane distance, with the dilaton now playing the role of
the stabilising field. We consider the coupled fluctuations of the metric and
dilaton fields and identify the physical scalar modes of the system. The
wavefunctions and masses of the radion and Kaluza-Klein modes are calculated,
giving a radion mass of order the curvature scale. As a result of the direct
coupling between the dilaton and Standard Model fields, the radion couples to
the SM Lagrangian, in addition to the trace of the energy-momentum tensor. The
effect of these additional interaction terms on the radion decay modes is
investigated, with a notable increase in the branching fraction to photons. We
also consider the effects of a non-minimal Higgs coupling to gravity, which
introduces a mixing between the Higgs and radion modes. Finally, we calculate
the production cross section of the radion at the LHC and use the current Higgs
searches to place constraints on the parameter space.Comment: 28 pages, 7 figures; v2: error in radion-gauge boson Feynman rules
corrected, version published in JHE
Extending the Real-Time Maude Semantics of Ptolemy to Hierarchical DE Models
This paper extends our Real-Time Maude formalization of the semantics of flat
Ptolemy II discrete-event (DE) models to hierarchical models, including modal
models. This is a challenging task that requires combining synchronous
fixed-point computations with hierarchical structure. The synthesis of a
Real-Time Maude verification model from a Ptolemy II DE model, and the formal
verification of the synthesized model in Real-Time Maude, have been integrated
into Ptolemy II, enabling a model-engineering process that combines the
convenience of Ptolemy II DE modeling and simulation with formal verification
in Real-Time Maude.Comment: In Proceedings RTRTS 2010, arXiv:1009.398
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