26,091 research outputs found
Proximity-induced topological transition and strain-induced charge transfer in graphene/MoS2 bilayer heterostructures
Graphene/MoS2 heterostructures are formed by combining the nanosheets of
graphene and monolayer MoS2. The electronic features of both constituent
monolayers are rather well-preserved in the resultant heterostructure due to
the weak van der Waals interaction between the layers. However, the proximity
of MoS2 induces strong spin orbit coupling effect of strength ~1 meV in
graphene, which is nearly three orders of magnitude larger than the intrinsic
spin orbit coupling of pristine graphene. This opens a bandgap in graphene and
further causes anticrossings of the spin-nondegenerate bands near the Dirac
point. Lattice incommensurate graphene/MoS2 heterostructure exhibits
interesting moire' patterns which have been observed in experiments. The
electronic bandstructure of heterostructure is very sensitive to biaxial strain
and interlayer twist. Although the Dirac cone of graphene remains intact and no
charge-transfer between graphene and MoS2 layers occurs at ambient conditions,
a strain-induced charge-transfer can be realized in graphene/MoS2
heterostructure. Application of a gate voltage reveals the occurrence of a
topological phase transition in graphene/MoS2 heterostructure. In this chapter,
we discuss the crystal structure, interlayer effects, electronic structure,
spin states, and effects due to strain and substrate proximity on the
electronic properties of graphene/MoS2 heterostructure. We further present an
overview of the distinct topological quantum phases of graphene/MoS2
heterostructure and review the recent advancements in this field.Comment: 31 pages, 12 figure
Scalable quantum memory in the ultrastrong coupling regime
Circuit quantum electrodynamics, consisting of superconducting artificial
atoms coupled to on-chip resonators, represents a prime candidate to implement
the scalable quantum computing architecture because of the presence of good
tunability and controllability. Furthermore, recent advances have pushed the
technology towards the ultrastrong coupling regime of light-matter interaction,
where the qubit-resonator coupling strength reaches a considerable fraction of
the resonator frequency. Here, we propose a qubit-resonator system operating in
that regime, as a quantum memory device and study the storage and retrieval of
quantum information in and from the Z2 parity-protected quantum memory, within
experimentally feasible schemes. We are also convinced that our proposal might
pave a way to realize a scalable quantum random-access memory due to its fast
storage and readout performances.Comment: We have updated the title, abstract and included a new section on the
open-system dynamic
Models for gamma-ray production in low-mass microquasars
Unlike high-mass gamma-ray binaries, low-mass microquasars lack external
sources of radiation and matter that could produce high-energy emission through
interactions with relativistic particles. In this work we consider the
synchrotron emission of protons and leptons that populate the jet of a low-mass
microquasar. In our model photohadronic and inverse Compton (IC) interactions
with synchrotron photons produced by both protons and leptons result in a
high-energy tail of the spectrum. We also estimate the contribution from
secondary pairs injected through photopair production. The high-energy emission
is dominated by radiation of hadronic origin, so we can call these objects
proton microquasars.Comment: 4 pages, 2 figures, accepted for publication in the International
Journal of Modern Physics D, proceedings of HEPRO meeting, held in Dublin, in
September 200
Modeling of gas adsorption on graphene nanoribbons
We present a theory to study gas molecules adsorption on armchair graphene
nanoribbons (AGNRs) by applying the results of \emph{ab} \emph{initio}
calculations to the single-band tight-binding approximation. In addition, the
effect of edge states on the electronic properties of AGNR is included in the
calculations. Under the assumption that the gas molecules adsorb on the ribbon
sites with uniform probability distribution, the applicability of the method is
examined for finite concentrations of adsorption of several simple gas
molecules (CO, NO, CO, NH) on 10-AGNR. We show that the states
contributed by the adsorbed CO and NO molecules are quite localized near the
center of original band gap and suggest that the charge transport in such
systems cannot be enhanced considerably, while CO and NH molecules
adsorption acts as acceptor and donor, respectively. The results of this theory
at low gas concentration are in good agreement with those obtained by
density-functional theory calculations.Comment: 7 pages, 6 figure
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