9,135 research outputs found
Single-Particle Tunneling in Doped Graphene-Insulator-Graphene Junctions
The characteristics of tunnel junctions formed between n- and p-doped
graphene are investigated theoretically. The single-particle tunnel current
that flows between the two-dimensional electronic states of the graphene (2D-2D
tunneling) is evaluated. At a voltage bias such that the Dirac points of the
two electrodes are aligned, a large resonant current peak is produced. The
magnitude and width of this peak is computed, and its use for devices is
discussed. The influence of both rotational alignment of the graphene
electrodes and structural perfection of the graphene is discussed.Comment: 23 pages, 9 figures; added Section II(E) and associated figures, and
made other minor typographical correction
SymFET: A Proposed Symmetric Graphene Tunneling Field Effect Transistor
In this work, an analytical model to calculate the channel potential and
current-voltage characteristics in a Symmetric tunneling
Field-Effect-Transistor (SymFET) is presented. The current in a SymFET flows by
tunneling from an n-type graphene layer to a p-type graphene layer. A large
current peak occurs when the Dirac points are aligned at a particular drain-to-
source bias VDS . Our model shows that the current of the SymFET is very weakly
dependent on temperature. The resonant current peak is controlled by chemical
doping and applied gate bias. The on/off ratio increases with graphene
coherence length and doping. The symmetric resonant peak is a good candidate
for high-speed analog applications, and can enable digital logic similar to the
BiSFET. Our analytical model also offers the benefit of permitting simple
analysis of features such as the full-width-at-half-maximum (FWHM) of the
resonant peak and higher order harmonics of the nonlinear current. The SymFET
takes advantage of the perfect symmetry of the bandstructure of 2D graphene, a
feature that is not present in conventional semiconductors
Effective generation of Ising interaction and cluster states in coupled microcavities
We propose a scheme for realizing the Ising spin-spin interaction and atomic
cluster states utilizing trapped atoms in coupled microcavities. It is shown
that the atoms can interact with each other via the exchange of virtual photons
of the cavities. Through suitably tuning the parameters, an effective Ising
spin-spin interaction can be generated in this optical system, which is used to
produce the cluster states. This scheme does not need the preparation of
initial states of atoms and cavity modes, and is insensitive to cavity decay.Comment: 11pages, 2 figures, Revtex
Non-Abelian Quantum Hall Effect in Topological Flat Bands
Inspired by recent theoretical discovery of robust fractional topological
phases without a magnetic field, we search for the non-Abelian quantum Hall
effect (NA-QHE) in lattice models with topological flat bands (TFBs). Through
extensive numerical studies on the Haldane model with three-body hard-core
bosons loaded into a TFB, we find convincing numerical evidence of a stable
bosonic NA-QHE, with the characteristic three-fold quasi-degeneracy of
ground states on a torus, a quantized Chern number, and a robust spectrum gap.
Moreover, the spectrum for two-quasihole states also shows a finite energy gap,
with the number of states in the lower energy sector satisfying the same
counting rule as the Moore-Read Pfaffian state.Comment: 5 pages, 7 figure
Quantum-dot gain without inversion:Effects of dark plasmon-exciton hybridization
We propose an initial-state-dependent quantum-dot gain without population inversion in the vicinity of a resonant metallic nanoparticle. The gain originates from the hybridization of a dark plasmon-exciton and is accompanied by efficient energy transfer from the nanoparticle to the quantum dot. This hybridization of the dark plasmon-exciton, attached to the hybridization of the bright plasmon-exciton, strengthens nonlinear light-quantum emitter interactions at the nanoscale, thus the spectral overlap between the dark and the bright plasmons enhances the gain effect. This hybrid system has potential applications in ultracompact tunable quantum devices.Physics, Condensed MatterSCI(E)[email protected]
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