962 research outputs found
Remote information concentration and multipartite entanglement in multilevel systems
Remote information concentration (RIC) in -level systems (qudits) is
studied. It is shown that the quantum information initially distributed in
three spatially separated qudits can be remotely and deterministically
concentrated to a single qudit via an entangled channel without performing any
global operations. The entangled channel can be different types of genuine
multipartite pure entangled states which are inequivalent under local
operations and classical communication. The entangled channel can also be a
mixed entangled state, even a bound entangled state which has a similar form to
the Smolin state, but has different features from the Smolin state. A common
feature of all these pure and mixed entangled states is found, i.e., they have
common commuting stabilizers. The differences of qudit-RIC and qubit-RIC
() are also analyzed.Comment: 10 pages, 3 figure
Electric field enhancement of pool boiling of dielectric fluids on pillar-structured surfaces: A lattice Boltzmann study
In this paper, by using a phase-change lattice Boltzmann (LB) model coupled
with an electric field model, we numerically investigate the performance and
enhancement mechanism of pool boiling of dielectric fluids on pillar-structured
surfaces under an electric field. The numerical investigation reveals that
applying an electric field causes both positive and negative influences on the
pool boiling of dielectric fluids on pillar-structured surfaces. It is found
that, under the action of an electric field, the electric force prevents the
bubbles nucleated in the channels from crossing the edges of the pillar tops.
On the one hand, such an effect results in the bubble coalescence in the
channels and blocks the paths of liquid supply for the channels, which leads to
the deterioration of pool boiling in the medium-superheat regime. On the other
hand, it prevents the coalescence between the bubbles in the channels and those
on the pillar tops, which suppresses the formation of a continuous vapor film
and therefore delays the occurrence of boiling crisis. Meanwhile, the electric
force can promote the departure of the bubbles on the pillar tops. Accordingly,
the critical heat flux (CHF) can be improved. Based on the revealed mechanism,
wettability-modified regions are applied to the pillar tops for further
enhancing the boiling heat transfer. It is shown that the boiling performance
on pillar-structured surfaces can be enhanced synergistically with the CHF
being increased by imposing an electric field and the maximum heat transfer
coefficient being improved by applying mixed wettability to the
pillar-structured surfaces.Comment: 29 pages, 16 figure
(E)-2-{3-[4-(Diphenylamino)styryl]-5,5-dimethylcyclohex-2-enylidene}malononitrile
In the title compound, C31H27N3, the cyclohexene ring has an envelope configuration. In the crystal structure, there is an 34 Å3 void around the inversion center, but the low electron density (0.13 e Å−3) in the difference Fourier map suggests no solvent molecule occupying this void. No hydrogen bonding is found in the crystal structure
Supersensitive sensing of quantum reservoirs via breaking antisymmetric coupling
We investigate the utilization of a single generalized dephasing qubit for
sensing a quantum reservoir, where the antisymmetric coupling between the qubit
and its reservoir is broken. It is found that in addition to the decay factor
encoding channel, the antisymmetric coupling breaking gives rise to another
phase factor encoding channel. We introduce an optimal measurement for the
generalized dephasing qubit which enables the practical measurement precision
to reach the theoretical ultimate precision quantified by the quantum
signal-to-noise ratio (QSNR). As an example, the generalized dephasing qubit is
employed to estimate the -wave scattering length of an atomic Bose-Einstein
condensate. It is found that the phase-induced QSNR caused by the antisymmetric
coupling breaking is at least two orders of magnitude higher than the
decay-induced QSNR at the millisecond timescale and the optimal relative error
can achieve a scaling with being the encoding time in
long-term encoding. Our work opens a way for supersensitive sensing of quantum
reservoirs
Deep Time-Stream Framework for Click-Through Rate Prediction by Tracking Interest Evolution
Click-through rate (CTR) prediction is an essential task in industrial
applications such as video recommendation. Recently, deep learning models have
been proposed to learn the representation of users' overall interests, while
ignoring the fact that interests may dynamically change over time. We argue
that it is necessary to consider the continuous-time information in CTR models
to track user interest trend from rich historical behaviors. In this paper, we
propose a novel Deep Time-Stream framework (DTS) which introduces the time
information by an ordinary differential equations (ODE). DTS continuously
models the evolution of interests using a neural network, and thus is able to
tackle the challenge of dynamically representing users' interests based on
their historical behaviors. In addition, our framework can be seamlessly
applied to any existing deep CTR models by leveraging the additional
Time-Stream Module, while no changes are made to the original CTR models.
Experiments on public dataset as well as real industry dataset with billions of
samples demonstrate the effectiveness of proposed approaches, which achieve
superior performance compared with existing methods.Comment: 8 pages. arXiv admin note: text overlap with arXiv:1809.03672 by
other author
Quantum sensing of temperature close to absolute zero in a Bose-Einstein condensate
We propose a theoretical scheme for quantum sensing of temperature close to
absolute zero in a quasi-one-dimensional Bose-Einstein condensate (BEC). In our
scheme, a single-atom impurity qubit is used as a temper-ature sensor. We
investigate the sensitivity of the single-atom sensor in estimating the
temperature of the BEC. We demonstrate that the sensitivity of the temperature
sensor can saturate the quantum Cramer-Rao bound by means of measuring quantum
coherence of the probe qubit. We study the temperature sensing performance by
the use of quantum signal-to-noise ratio (QSNR). It is indicated that there is
an optimal encoding time that the QSNR can reach its maximum in the
full-temperature regime. In particular, we find that the QSNR reaches a finite
upper bound in the weak coupling regime even when the temperature is close to
absolute zero, which implies that the sensing-error-divergence problem is
avoided in our scheme. Our work opens a way for quantum sensing of temperature
close to absolute zero in the BEC.Comment: 9 pages,9 figure
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