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Universal slow plasmons and giant field enhancement in atomically thin quasi-two-dimensional metals
Plasmons depend strongly on dimensionality: while plasmons in three-dimensional systems start with finite energy at wavevector q = 0, plasmons in traditional two-dimensional (2D) electron gas disperse as ωp∼q√. However, besides graphene, plasmons in real, atomically thin quasi-2D materials were heretofore not well understood. Here we show that the plasmons in real quasi-2D metals are qualitatively different, being virtually dispersionless for wavevectors of typical experimental interest. This stems from a broken continuous translational symmetry which leads to interband screening; so, dispersionless plasmons are a universal intrinsic phenomenon in quasi-2D metals. Moreover, our ab initio calculations reveal that plasmons of monolayer metallic transition metal dichalcogenides are tunable, long lived, able to sustain field intensity enhancement exceeding 107, and localizable in real space (within ~20 nm) with little spreading over practical measurement time. This opens the possibility of tracking plasmon wave packets in real time for novel imaging techniques in atomically thin materials
On the scalar nonet in the extended Nambu Jona-Lasinio model
We discuss the lightest scalar resonances, , ,
and in the extended Nambu Jona-Lasinio model. We find
that the model parameters can be tuned, but unnaturally, to accommodate for
those scalars except the . We also discuss problems encountered in
the K Matrix unitarization approximation by using counting technique.Comment: 23 pages 3 eps figures, To appear in Nucl. Phys.
Two-dimensional Poisson Trees converge to the Brownian web
The Brownian web can be roughly described as a family of coalescing
one-dimensional Brownian motions starting at all times in and at all
points of . It was introduced by Arratia; a variant was then studied by
Toth and Werner; another variant was analyzed recently by Fontes, Isopi, Newman
and Ravishankar. The two-dimensional \emph{Poisson tree} is a family of
continuous time one-dimensional random walks with uniform jumps in a bounded
interval. The walks start at the space-time points of a homogeneous Poisson
process in and are in fact constructed as a function of the point
process. This tree was introduced by Ferrari, Landim and Thorisson. By
verifying criteria derived by Fontes, Isopi, Newman and Ravishankar, we show
that, when properly rescaled, and under the topology introduced by those
authors, Poisson trees converge weakly to the Brownian web.Comment: 22 pages, 1 figure. This version corrects an error in the previous
proof. The results are the sam
Non-Markov dynamics and phonon decoherence of a double quantum dot charge qubit
In this paper we investigate decoherence times of a double quantum dot (DQD)
charge qubit due to it coupling with acoustic phonon baths. We individually
consider the acoustic piezoelectric as well as deformation coupling phonon
baths in the qubit environment. The decoherence times are calculated with two
kinds of methods. One of them is based on the qusiadiabatic propagator path
integral (QUAPI) and the other is based on Bloch equations, and two kinds of
results are compared. It is shown that the theoretical decoherence times of the
DQD charge qubit are shorter than the experimental reported results. It implies
that the phonon couplings to the qubit play a subordinate role, resulting in
the decoherence of the qubit.Comment: 5 pages, 4 figure
Germanene: a novel two-dimensional Germanium allotrope akin to Graphene and Silicene
Using a gold (111) surface as a substrate we have grown in situ by molecular
beam epitaxy an atom-thin, ordered, two-dimensional multi-phase film. Its
growth bears strong similarity with the formation of silicene layers on silver
(111) templates. One of the phases, forming large domains, as observed in
Scanning Tunneling Microscopy, shows a clear, nearly flat, honeycomb structure.
Thanks to thorough synchrotron radiation core-level spectroscopy measurements
and advanced Density Functional Theory calculations we can identify it to a
xR(30{\deg}) germanene layer in coincidence with a
xR(19.1{\deg}) Au(111) supercell, thence, presenting the
first compelling evidence of the birth of a novel synthetic germanium-based
cousin of graphene.Comment: 16 pages, 4 figures, 1 tabl
Electro-diffusion in a plasma with two ion species
Electric field is a thermodynamic force that can drive collisional
inter-ion-species transport in a multicomponent plasma. In an inertial
confinement fusion (ICF) capsule, such transport causes fuel ion separation
even with a target initially prepared to have equal number densities for the
two fuel ion species. Unlike the baro-diffusion driven by ion pressure gradient
and the thermo-diffusion driven by ion and electron temperature gradients,
electro-diffusion has a critical dependence on the charge-to-mass ratio of the
ion species. Specifically, it is shown here that electro-diffusion vanishes if
the ion species have the same charge-to-mass ratio. An explicit expression for
the electro-diffusion ratio is obtained and used to investigate the relative
importance of electro- and baro-diffusion mechanisms. In particular, it is
found that electro-diffusion reinforces baro-diffusion in the deuterium and
tritium mix, but tends to cancel it in the deuterium and helium-3 mix.Comment: Submitted to Phys. Plasmas on 2012-03-06 (revised version 05/13/2012
Страна детства выдающегося ученого
Рецензія на книгу: Соколов Б.С. Записки с берегов Имоложья. — СПб.: Рериховский центр СПбГУ; Вышний Волочёк: Ирида-пресс, 2007. — 448 с. (Серия «Щедрый дар». — Вып.. IV).Академик РАН Борис Сергеевич Соколов — крупнейший ученый-естествоиспытатель, широко известный на постсоветском пространстве и за рубежом трудами по палеонтологии ископаемых кораллов и древнейшим группам органического мира, по стратиграфии, палеогео графии, региональной геологии, геологии нефти и газа Русской платформы, Сибири, Средней Азии и Китая, а также развитием учения В.И. Вернадского о биосфере. Б.С. Соколов — лауреат Ленинской премии (1967), Герой Социалистического Труда (1984), лауреат международной премии имени Карпинского — Швейцера, российской независимой премии «Триумф» и международной премии имени Николая Рериха, три десятка лет он возглавлял в СССР и России авторитетнейшее научное общество — Палеонтологическое, с 1980 г. — президент Международной палеонтологической ассоциации
Latest Observational Constraints to the Ghost Dark Energy Model by Using Markov Chain Monte Carlo Approach
Recently, the vacuum energy of the QCD ghost in a time-dependent background
is proposed as a kind of dark energy candidate to explain the acceleration of
the universe. In this model, the energy density of the dark energy is
proportional to the Hubble parameter , which is the Hawking temperature on
the Hubble horizon of the Friedmann-Robertson-Walker (FRW) universe. In this
paper, we perform a constraint on the ghost dark energy model with and without
bulk viscosity, by using the Markov Chain Monte Carlo (MCMC) method and the
combined latest observational data from the type Ia supernova compilations
including Union2.1(580) and Union2(557), cosmic microwave background, baryon
acoustic oscillation, and the observational Hubble parameter data.Comment: 12 pages, 4 figure
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