2,526 research outputs found

    Apparent slow dynamics in the ergodic phase of a driven many-body localized system without extensive conserved quantities

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    We numerically study the dynamics on the ergodic side of the many-body localization transition in a periodically driven Floquet model with no global conservation laws. We describe and employ a numerical technique based on the fast Walsh-Hadamard transform that allows us to perform an exact time evolution for large systems and long times. As in models with conserved quantities (e.g., energy and/or particle number) we observe a slowing down of the dynamics as the transition into the many-body localized phase is approached. More specifically, our data is consistent with a subballistic spread of entanglement and a stretched-exponential decay of an autocorrelation function, with their associated exponents reflecting slow dynamics near the transition for a fixed system size. However, with access to larger system sizes, we observe a clear flow of the exponents towards faster dynamics and can not rule out that the slow dynamics is a finite-size effect. Furthermore, we observe examples of non-monotonic dependence of the exponents with time, with dynamics initially slowing down but accelerating again at even larger times, consistent with the slow dynamics being a crossover phenomena with a localized critical point.Comment: 9 pages, 8 figures; added details on the level statistics and the energy absorptio

    Surface Reconstruction and Evolution from Multiple Views

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    Applications like 3D Telepresence necessitate faithful 3D surface reconstruction of the object and 3D data compression in both spatial and temporal domains. This makes us feel immersed in virtual environments there by making 3D Telepresence a powerful tool in many applications. Hence 3D surface reconstruction and 3D compression are two challenging problems which are addressed in this thesis

    A Hybrid Procreative –Discriminative Based Hashing Method

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    Hashing method is the one of the main method for searching same and different images based on hash code.For capturing similarities between textual, visual and cross media information; a hashing approaches have been proven. To address these challenges, in this paper we propose semantic level cross media hashing (SCMH) and deep belief network (DBN) is for a co-relation between different modalities

    Towards a real-time fully-coherent all-sky search for gravitational waves from compact binary coalescences using particle swarm optimization

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    While a fully-coherent all-sky search is known to be optimal for detecting gravitational wave signals from compact binary coalescences, its high computational cost has limited current searches to less sensitive coincidence-based schemes. Following up on previous work that has demonstrated the effectiveness of particle swarm optimization (PSO) in reducing the computational cost of this search, we present an implementation that achieves near real-time computational speed. This is achieved by combining the search efficiency of PSO with a significantly revised and optimized numerical implementation of the underlying mathematical formalism along with additional multithreaded parallelization layers in a distributed computing framework. For a network of four second-generation detectors with 60 min data from each, the runtime of the implementation presented here ranges between ≈1.4 to ≈0.5 times the data duration for network signal-to-noise ratios (SNRs) of ≳10 and ≳12, respectively. The reduced runtimes are obtained with small to negligible losses in detection sensitivity: for a false alarm rate of ≃1 event per year in Gaussian stationary noise, the loss in detection probability is ≤5% and ≤2% for SNRs of 10 and 12, respectively. Using the fast implementation, we are able to quantify frequentist errors in parameter estimation for signals in the double neutron star mass range using a large number of simulated data realizations. A clear dependence of parameter estimation errors and detection sensitivity on the condition number of the network antenna pattern matrix is revealed. Combined with previous work, this paper securely establishes the effectiveness of PSO-based fully-coherent all-sky search across the entire binary inspiral mass range that is relevant to ground-based detectors
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