18,464 research outputs found
Pinned Bilayer Wigner Crystals with Pseudospin Magnetism
We study a model of \textit{pinned} bilayer Wigner crystals (WC) and focus on
the effects of interlayer coherence (IC) on pinning. We consider both a
pseudospin ferromagnetic WC (FMWC) with IC and a pseudospin antiferromagnetic
WC (AFMWC) without IC. Our central finding is that a FMWC can be pinned more
strongly due to the presence of IC. One specific mechanism is through the
disorder induced interlayer tunneling, which effectively manifests as an extra
pinning in a FMWC. We also construct a general "effective disorder" model and
effective pinning Hamiltonian for the case of FMWC and AFMWC respectively.
Under this framework, pinning in the presence of IC involves
\textit{interlayer} spatial correlation of disorder in addition to intralayer
correlation, leading to \textit{enhanced} pinning in the FMWC. The pinning mode
frequency (\wpk) of a FMWC is found to decease with the effective layer
separation, whereas for an AFMWC the opposite behavior is expected. An abrupt
drop of \wpk is predicted at a transition from a FMWC to AFMWC. Possible
effects of in-plane magnetic fields and finite temperatures are addressed.
Finally we discuss some other possible ramifications of the FMWC as an
electronic supersolid-like phase.Comment: Slightly revised. The final version is published on PR
Estimates for X(4350) Decays from the Effective Lagrangian Approach
The strong and electromagnetic decays of with quantum numbers and have been studied by using the effective Lagrangian
approach. The coupling constant between and
is determined with the help of the compositeness condition which means that
is a bound state of . Other coupling
constants applied in the calculation are determined phenomenologically. Our
numerical results show that, using the present data within the present model,
the possibility that is a molecule can not
be ruled out.Comment: 15 pages, 4 eps figure
On-Demand Spin-Orbit Interaction from Which-Layer Tunability in Bilayer Graphene
Spin-orbit interaction (SOI) that is gate-tunable over a broad range is
essential to exploiting novel spin phenomena. Achieving this regime has
remained elusive because of the weakness of the underlying relativistic
coupling and lack of its tunability in solids. Here we outline a general
strategy that enables exceptionally high tunability of SOI through creating a
which-layer spin-orbit field inhomogeneity in graphene multilayers. An external
transverse electric field is applied to shift carriers between the layers with
strong and weak SOI. Because graphene layers are separated by sub-nm scales,
exceptionally high tunability of SOI can be achieved through a minute carrier
displacement. A detailed analysis of the experimentally relevant case of
bilayer graphene on a semiconducting transition metal dichalchogenide substrate
is presented. In this system, a complete tunability of SOI amounting to its
ON/OFF switching can be achieved. New opportunities for spin control are
exemplified with electrically driven spin resonance and topological phases with
different quantized intrinsic valley Hall conductivities.Comment: 8 pages, 3 figure
Complex networks in climate dynamics - Comparing linear and nonlinear network construction methods
Complex network theory provides a powerful framework to statistically
investigate the topology of local and non-local statistical interrelationships,
i.e. teleconnections, in the climate system. Climate networks constructed from
the same global climatological data set using the linear Pearson correlation
coefficient or the nonlinear mutual information as a measure of dynamical
similarity between regions, are compared systematically on local, mesoscopic
and global topological scales. A high degree of similarity is observed on the
local and mesoscopic topological scales for surface air temperature fields
taken from AOGCM and reanalysis data sets. We find larger differences on the
global scale, particularly in the betweenness centrality field. The global
scale view on climate networks obtained using mutual information offers
promising new perspectives for detecting network structures based on nonlinear
physical processes in the climate system.Comment: 24 pages, 10 figure
Second-order superposition operations via Hong-Ou-Mandel interference
We propose an experimental scheme to implement a second-order nonlocal
superposition operation and its variants by way of Hong-Ou-Mandel interference.
The second-order coherent operations enable us to generate a NOON state with
high particle number in a heralded fashion and also can be used to enhance the
entanglement properties of continuous variable states. We discuss the
feasibility of our proposed scheme considering realistic experimental
conditions such as on-off photodetectors with nonideal efficiency and imperfect
single-photon sources.Comment: published version, 6 pages, 6 figure
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