4,895 research outputs found
Reconstructing black hole exteriors and interiors using entanglement and complexity
Based on the AdS/CFT correspondence, we study how to reconstruct bulk
spacetime metrics by various quantum information measures on the boundary field
theories, which include entanglement entropy, mutual information, entanglement
of purification, and computational complexity according to the proposals of
complexity=volume 2.0 and complexity=generalized volume. We present several
reconstruction methods, all of which are free of UV divergence and most of
which are driven by the derivatives of the measures with respect to the
boundary scales. We illustrate that the exterior and interior of a black hole
can be reconstructed using the measures of spatial entanglement and
time-evolved complexity, respectively. We find that these measures always probe
the spacetime in a local way: reconstructing the bulk metric in different
radial positions requires the information at different boundary scales. We also
show that the reconstruction method using complexity=volume 2.0 proposal is the
simplest and has the strongest locality.Comment: 25 pages, 18 figures, 1 tabl
Extracting spinning wormhole energy via magnetic reconnection
Magnetic reconnection has been extensively shown to be a promising approach
to extract spinning black hole energy. In this paper, we focus on extracting
spinning wormhole energy via such mechanism. The study shows that it is indeed
possible to extract rotating energy from a spinning wormhole with small
regularization parameter of the central singularity. The efficiency and
power of the energy extraction are also evaluated. Quite different from the
Kerr black hole, the spin of the wormhole can take arbitrarily large value.
However, the increasing of wormhole spin not always improves the efficiency and
power of energy extraction. By further comparing with the Kerr black hole, we
find the wormhole is more efficient when the magnetic reconnection happens
within radial distance . These studies reveal the features of extracting
spinning wormhole energy, and more underlying properties are expected to be
disclosed for the horizonless objects.Comment: 15 pages and 8 figures, references adde
Realization of Zero-Refractive-Index Lens with Ultralow Spherical Aberration
Optical complex materials offer unprecedented opportunity to engineer
fundamental band dispersion which enables novel optoelectronic functionality
and devices. Exploration of photonic Dirac cone at the center of momentum space
has inspired an exceptional characteristic of zero-index, which is similar to
zero effective mass in fermionic Dirac systems. Such all-dielectric zero-index
photonic crystals provide an in-plane mechanism such that the energy of the
propagating waves can be well confined along the chip direction. A
straightforward example is to achieve the anomalous focusing effect without
longitudinal spherical aberration, when the size of zero-index lens is large
enough. Here, we designed and fabricated a prototype of zero-refractive-index
lens by comprising large-area silicon nanopillar array with plane-concave
profile. Near-zero refractive index was quantitatively measured near 1.55 um
through anomalous focusing effect, predictable by effective medium theory. The
zero-index lens was also demonstrated to perform ultralow longitudinal
spherical aberration. Such IC compatible device provides a new route to
integrate all-silicon zero-index materials into optical communication, sensing,
and modulation, and to study fundamental physics on the emergent fields of
topological photonics and valley photonics.Comment: 14 pages, 4 figure
Long and Diverse Text Generation with Planning-based Hierarchical Variational Model
Existing neural methods for data-to-text generation are still struggling to
produce long and diverse texts: they are insufficient to model input data
dynamically during generation, to capture inter-sentence coherence, or to
generate diversified expressions. To address these issues, we propose a
Planning-based Hierarchical Variational Model (PHVM). Our model first plans a
sequence of groups (each group is a subset of input items to be covered by a
sentence) and then realizes each sentence conditioned on the planning result
and the previously generated context, thereby decomposing long text generation
into dependent sentence generation sub-tasks. To capture expression diversity,
we devise a hierarchical latent structure where a global planning latent
variable models the diversity of reasonable planning and a sequence of local
latent variables controls sentence realization. Experiments show that our model
outperforms state-of-the-art baselines in long and diverse text generation.Comment: To appear in EMNLP 201
Evaluation of Ischemia-Modified Albumin and C-Reactive Protein in Type 2 Diabetics With and Without Ketosis
QED effects on phase transition and Ruppeiner geometry of Euler-Heisenberg-AdS black holes
Taking the quantum electrodynamics (QED) effect into account, we study the
black hole phase transition and Ruppeiner geometry for the Euler-Heisenberg
anti-de Sitter black hole in the extended phase space. For negative and small
positive QED parameter, we observe a small/large black hole phase transition
and reentrant phase transition, respectively. While a large positive value of
the QED parameter ruins the phase transition. The phase diagrams for each case
are explicitly exhibited. Then we construct the Ruppeiner geometry in the
thermodynamic parameter space. Different features of the corresponding scalar
curvature are shown for both the small/large black hole phase transition and
reentrant phase transition cases. Of particular interest is that an additional
region of positive scalar curvature indicating dominated repulsive interaction
among black hole microstructure is present for the black hole with a small
positive QED parameter. Furthermore, the universal critical phenomena are also
observed for the scalar curvature of the Ruppeiner geometry. These results
indicate that the QED parameter has a crucial influence on the black hole phase
transition and microstructure.Comment: 19 pages, 14 figure
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