A Study on the Sudden Death of Entanglement

The dynamics of entanglement and the phenomenon of entanglement sudden death (ESD) \cite{yu} are discussed in bipartite systems, measured by Wootters Concurrence. Our calculation shows that ESD appears whenever the system is open or closed and is dependent on the initial condition. The relation of the evolution of entanglement and energy transfer between the system and its surroundings is also studied.Comment: Comments and criticism are welcome. Accepted by Phys. Lett.

Magnetic Properties And Giant Magnetoresistance Of Magnetic Granular Co10cu90 Alloys Obtained By Direct-current Joule Heating

The direct-current (dc) joule heating technique was exploited to fabricate giant magnetoresistance (GMR) Co10Cu90 granular alloys. The Co cluster precipitation process was investigated by calorimetric and x-ray diffraction measurements. At T=10 K, the largest MR change of 25.0% has been observed for the melt-spun Co10Cu90 ribbon annealed at I=5 A. The magnetoresistance scales approximately as the inverse Co particle size. At room temperature, it was found that the dc joule-heated samples show relatively high GMR in comparison with furnace-annealed samples. Based on the phenomenological GMR model, we assumed that it is a consequence of smaller Co particles formed in dc joule-heated samples. © 1995 American Institute of Physics.7885062506

Markov evolutions and hierarchical equations in the continuum I. One-component systems

General birth-and-death as well as hopping stochastic dynamics of infinite particle systems in the continuum are considered. We derive corresponding evolution equations for correlation functions and generating functionals. General considerations are illustrated in a number of concrete examples of Markov evolutions appearing in applications.Comment: 47 page

Interference between the halves of a double-well trap containing a Bose-Einstein condensate

Interference between the halves of a double-well trap containing a Bose-Einstein condensate is studied. It is found that when the atoms in the two wells are initially in the coherent state, the intensity exhibits collapses and revivals, but it does not for the initial Fock states. Whether the initial states are in the coherent states or in a Fock states, the fidelity time has nothing to do with collision. We point out that interference and its fidelity can be adjusted experimentally by properly preparing the number and initial states of the system.Comment: 10 pages, 3 figures, accepted by Phy. rev.

Surface structure and solidification morphology of aluminum nanoclusters

Classical molecular dynamics simulation with embedded atom method potential had been performed to investigate the surface structure and solidification morphology of aluminum nanoclusters Aln (n = 256, 604, 1220 and 2048). It is found that Al cluster surfaces are comprised of (111) and (001) crystal planes. (110) crystal plane is not found on Al cluster surfaces in our simulation. On the surfaces of smaller Al clusters (n = 256 and 604), (111) crystal planes are dominant. On larger Al clusters (n = 1220 and 2048), (111) planes are still dominant but (001) planes can not be neglected. Atomic density on cluster (111)/(001) surface is smaller/larger than the corresponding value on bulk surface. Computational analysis on total surface area and surface energies indicates that the total surface energy of an ideal Al nanocluster has the minimum value when (001) planes occupy 25% of the total surface area. We predict that a melted Al cluster will be a truncated octahedron after equilibrium solidification.Comment: 22 pages, 6 figures, 34 reference

Predicted robustness as QoS for Deep Neural Network Models

The adoption of deep neural network (DNN) model as the integral part of real-world software systems necessitates explicit consideration of their quality-of-service (QoS). It is well-known that DNN models are prone to adversarial attacks, and thus it is vitally important to be aware of how robust a model’s prediction is for a given input instance. A fragile prediction, even with high confidence, is not trustworthy in light of the possibility of adversarial attacks. We propose that DNN models should produce a robustness value as an additional QoS indicator, along with the confidence value, for each prediction they make. Existing approaches for robustness computation are based on adversarial searching, which are usually too expensive to be excised in real time. In this paper, we propose to predict, rather than to compute, the robustness measure for each input instance. Specifically, our approach inspects the output of the neurons of the target model and trains another DNN model to predict the robustness. We focus on convolutional neural network (CNN) models in the current research. Experiments show that our approach is accurate, with only 10%–34% additional errors compared with the offline heavy-weight robustness analysis. It also significantly outperforms some alternative methods. We further validate the effectiveness of the approach when it is applied to detect adversarial attacks and out-of-distribution input. Our approach demonstrates a better performance than, or at least is comparable to, the state-of-the-art techniques

Noise-assisted preparation of entangled atoms

We discuss the generation of entangled states of two two-level atoms inside an optical cavity. The cavity mode is supposed to be coupled to a white noise with adjustable intensity. We describe how the entanglement between the atoms inside the cavity arise in such a situation. The entanglement is maximized for intermediate values of the noise intensity, while it is a monotonic function of the spontaneous rate. This resembles the phenomenon of stochastic resonance and sheds more light on the idea to exploit white noise in quantum information processing.Comment: 4 pages, 4 figure

Observation of thundercloud-related gamma rays and neutrons in Tibet

During the 2010 rainy season in Yangbajing (4300 m above sea level) in Tibet, China, a long-duration count enhancement associated with thunderclouds was detected by a solar-neutron telescope and neutron monitors installed at the Yangbajing Comic Ray Observatory. The event, lasting for ∼40  min, was observed on July 22, 2010. The solar-neutron telescope detected significant γ-ray signals with energies >40  MeV in the event. Such a prolonged high-energy event has never been observed in association with thunderclouds, clearly suggesting that electron acceleration lasts for 40 min in thunderclouds. In addition, Monte Carlo simulations showed that >10  MeV γ rays largely contribute to the neutron monitor signals, while >1  keV neutrons produced via a photonuclear reaction contribute relatively less to the signals. This result suggests that enhancements of neutron monitors during thunderstorms are not necessarily clear evidence for neutron production, as previously thought

Pairing in two-dimensional boson-fermion mixtures

The possibilities of pairing in two-dimensional boson-fermion mixtures are carefully analyzed. It is shown that the boson-induced attraction between two identical fermions dominates the p-wave pairing at low density. For a given fermion density, the pairing gap becomes maximal at a certain optimal boson concentration. The conditions for observing pairing in current experiments are discussedComment: 10 pages, 5 figs, revtex