9,332 research outputs found
Fermions tunnelling with quantum gravity correction
Quantum gravity correction is truly important to study tunnelling process of
black hole. Base on the generalized uncertainty principle, we investigate the
influence of quantum gravity and the result tell us that the quantum gravity
correction accelerates the evaporation of black hole. Using corrected Dirac
equation in curved spacetime and Hamilton-Jacobi method, we address the
tunnelling of fermions in a 4-dimensional Schwarzschild spacetime.
After solving the equation of motion of the spin 1/2 field, we obtain the
corrected Hawking temperature. It turns out that the correction depends not
only on the mass of black hole but aslo on the mass of emitted fermions. In our
calculation, the quantum gravity correction accelerates the increasing of
Hawking temperature during the radiation explicitly. This correction leads to
the increasing of the evaporation of black hole.Comment: 5page
No-go theorem and optimization of dynamical decoupling against noise with soft cutoff
We study the performance of dynamical decoupling in suppressing decoherence
caused by soft-cutoff Gaussian noise, using short-time expansion of the noise
correlations and numerical optimization. For the noise with soft cutoff at high
frequencies, there exists no dynamical decoupling scheme to eliminate the
decoherence to arbitrary orders of the short time, regardless of the timing or
pulse shaping of the control under the population conserving condition. We
formulate the equations for optimizing pulse sequences that minimizes
decoherence up to the highest possible order of the short time for the noise
correlations with odd power terms in the short-time expansion. In particular,
we show that the Carr-Purcell-Meiboom-Gill sequence is optimal in short-time
limit for the noise correlations with a linear order term in the time
expansion.Comment: 11 pages, 3 figure
Quantum-speed-limit time for multiqubit open systems
Quantum-speed-limit (QSL) time captures the intrinsic minimal time interval
for a quantum system evolving from an initial state to a target state. In
single qubit open systems, it was found that the memory (non-Markovian) effect
of environment plays an essential role in shortening QSL time or, say,
increasing the capacity for potential speedup. In this paper, we investigate
the QSL time for multiqubit open systems. We find that for a certain class of
states the memory effect still acts as the indispensable requirement for
cutting the QSL time down, while for another class of states this takes place
even when the environment is of no memory. In particular, when the initial
state is in product state |111...1>, there exists a sudden transition from no
capacity for potential speedup to potential speedup in a memoryless
environment. In addition, we also display evidence for the subtle connection
between QSL time and entanglement that weak entanglement may shorten QSL time
even more.Comment: 5pages, 3 figure
Brane structure and metastable graviton in five-dimensional model with (non)canonical scalar field
The appearance of inner brane structure is an interesting issue in domain
wall {brane model}. Because such structure usually leads to quasilocalized
modes of various kinds of bulk fields. In this paper, we construct a domain
wall brane model by using a scalar field , which couples to its kinetic
term. The inner brane structure emerges as the scalar-kinetic coupling
increases. With such brane structure, we show that it is possible to obtain
gravity resonant modes in both tensor and scalar sectors. The number of the
resonant modes depends on the vacuum expectation value of and the form
of scalar-kinetic coupling. The correspondence between our model and the
canonical one is also discussed. The noncanonical and canonical background
scalar fields are connected by an integral equation, while the warp factor
remains the same. Via this correspondence, the canonical and noncanonical
models share the same linear perturbation spectrum. So the gravity resonances
{obtained} in the noncanonical frame can also be obtained in the standard
model. However, due to the inequivalence between the corresponding background
scalar solutions, the localization condition for the left-chiral fermion zero
mode can be largely different in different frames. Our estimate shows that the
magnitude of the Yukawa coupling in the noncanonical frame might be hundreds
times larger than the one in the canonical frame, if one demands the
localization of the left-chiral fermion zero mode as well as the appearance of
a few gravity resonance modes.Comment: 24 pages, 10 figure
Non-perturbative procedure for stable -brane
We propose a novel first-order formalism for a type of -brane systems. An
example solution is presented and studied. We illustrate how the noncanonical
kinetic term can affect the properties of the model, such as the stability of
the solutions, the localization of fermion and graviton. We argue that our
solution is stable against linear perturbations. The tensor zero mode of
graviton can be localized while the scalar zero mode cannot. The localization
condition for fermion is also discussed.Comment: 7 pages, 3 figure
Holographic Josephson Junction in 3+1 dimensions
In arXiv:1101.3326[hep-th], a (2+1)-dimensional holographic Josephson
junction was constructed, and it was shown that the DC Josephson current is
proportional to the sine of the phase difference across the junction. In this
paper, we extend this study to a holographic description for the
(3+1)-dimensional holographic DC Josephson junction. By solving numerically the
coupled differential equations, we also obtain the familiar characteristics of
Josephson junctions.Comment: 8 pages, 4 figure
Non-Markovian effect on remote state preparation
Memory effect of non-Markovian dynamics in open quantum systems is often
believed to be beneficial for quantum information processing. In this work, we
employ an experimentally controllable two-photon open system, with one photon
experiencing a dephasing environment and the other being free from noise, to
show that non-Markovian effect may also have a negative impact on quantum tasks
such as remote state preparation: For a certain period of controlled time
interval, stronger non-Markovian effect yields lower fidelity of remote state
preparation, as opposed to the common wisdom that more information leads to
better performance. As a comparison, a positive non-Markovian effect on the RSP
fidelity with another typical non-Markovian noise is analyzed. Consequently,
the observed dual character of non-Markovian effect will be of great importance
in the field of open systems engineering.Comment: 7 pages, 5 figure
Part-of-Speech Relevance Weights for Learning Word Embeddings
This paper proposes a model to learn word embeddings with weighted contexts
based on part-of-speech (POS) relevance weights. POS is a fundamental element
in natural language. However, state-of-the-art word embedding models fail to
consider it. This paper proposes to use position-dependent POS relevance
weighting matrices to model the inherent syntactic relationship among words
within a context window. We utilize the POS relevance weights to model each
word-context pairs during the word embedding training process. The model
proposed in this paper paper jointly optimizes word vectors and the POS
relevance matrices. Experiments conducted on popular word analogy and word
similarity tasks all demonstrated the effectiveness of the proposed method.Comment: Word embedding
Topological Supersolidity of Dipolar Fermi Gases in a Spin-Dependent Optical Lattice
We investigate topological supersolidity of dipolar Fermi gases in a
spin-dependent 2D optical lattice. Numerical results show that the topological
supersolid states can be synthesized via the combination of topological
superfluid states with the stripe order, where the topological superfluid
states generated with dipolar interaction possess the
order, and it is of D class topological classification. By adjusting the ratio
between hopping amplitude and interaction strength with
dipole orientation , the system will undergo phase
transitions among the -wave topological superfluid state, the
p-wave superfluid state, and the topological supersolid state. The topological
supersolid state is proved to be stable by the positive sign of the inverse
compressibility. We design an experimental protocol to realize the staggered
next-next-nearest-neighbour hopping via the laser assisted tunneling technique,
which is the key to synthesize topological supersolid states.Comment: 5 pages with 6 figure
Impact of Preference and Equivocators on Opinion Dynamics with Evolutionary Game Framework
Opinion dynamics, aiming to understand the evolution of collective behavior
through various interaction mechanisms of opinions, represents one of the most
challenges in natural and social science. To elucidate this issue clearly,
binary opinion model becomes a useful framework, where agents can take an
independent opinion. Inspired by the realistic observations, here we propose
two basic interaction mechanisms of binary opinion model: one is the so-called
BSO model in which players benefit from holding the same opinion; the other is
called BDO model in which players benefit from taking different opinions. In
terms of these two basic models, the synthetical effect of opinion preference
and equivocators on the evolution of binary opinion is studied under the
framework of evolutionary game theory (EGT), where the replicator equation (RE)
is employed to mimick the evolution of opinions. By means of numerous
simulations, we show the theoretical equilibrium states of binary opinion
dynamics, and mathematically analyze the stability of each equilibrium state as
well.Comment: 15 pages, 6 figure
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