1,512 research outputs found
Reflected entropy and Markov gap in Lifshitz theories
We study the reflected entropy in -dimensional Lifshitz field theory
whose groundstate is described by a quantum mechanical model. Starting from
tripartite Lifshitz groundstates, both critical and gapped, we derive explicit
formulas for the R\'enyi reflected entropies reduced to two adjacent or
disjoint intervals, directly in the continuum. We show that the reflected
entropy in Lifshitz theory does not satisfy monotonicity, in contrast to what
is observed for free relativistic fields. We analytically compute the full
reflected entanglement spectrum for two disjoint intervals, finding a discrete
set of eigenvalues which is that of a thermal density matrix. Furthermore, we
investigate the Markov gap, defined as the difference between reflected entropy
and mutual information, and find it to be nonvanishing, signaling irreducible
tripartite entanglement in Lifshitz groundstates. As a byproduct of our results
on reflected entropy, we provide exact formulas for two other
entanglement-related quantities, namely the computable cross-norm negativity
and the operator entanglement entropy.Comment: 34 pages, 12 figure
TiO2 Nanocrystals Grown on Graphene as Advanced Photocatalytic Hybrid Materials
Graphene/TiO2 nanocrystals hybrid is successfully prepared by directly
growing TiO2 nanocrystals on graphene oxide (GO) sheets. The direct growth of
nanocrystals on GO sheets was achieved by a two-step method, in which TiO2 was
coated on GO sheets by hydrolysis first and crystallized into anatase
nanocrystals by hydrothermal treatment in second step. Slow hydrolysis reaction
through the use of EtOH/H2O mixed solvents and addition of H2SO4 allows the
selectively growing TiO2 on GO and suppressing free growth in solution. The
method offers easy access to the GO/TiO2 nanocrystals hybrid with well
controlled coating and strong interactions between TiO2 and the underlying GO
sheets. The strong coupling could lead to advanced hybrid materials for various
applications including photocatalysis. The prepared graphene/TiO2 nanocrystals
hybrid has demonstrated superior photocatalytic activity in degradation of
rhodamine B over other TiO2 materials, showing an impressive 3-fold
photocatalytic enhancement over P25. It is expected that the hybrid material
could also be promising for various other applications including lithium ion
battery where strong electrical coupling to TiO2 nanoparticles is essential.Comment: Nano Research, in pres
Freestanding dielectric nanohole array metasurface for mid-infrared wavelength applications
We designed and simulated freestanding dielectric optical metasurfaces based
on arrays of etched nanoholes in a silicon membrane. We showed phase
control and high forward transmission at mid-infrared wavelengths by tuning the
dimensions of the holes. We also identified the mechanisms responsible for high
forward scattering efficiency and showed that these conditions are connected
with the well-known Kerker conditions already proposed for isolated scatterers.
A beam deflector was designed and optimized through sequential particle swarm
and gradient descent optimization to maximize transmission efficiency and
reduce unwanted grating orders. Such freestanding silicon nanohole array
metasurfaces are promising for the realization of silicon based mid-infrared
optical elements
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