6,155 research outputs found
Properties of Macroscopic Quantum Effects and Dynamic Natures of Electrons in Superconductors
Simulation of an all-optical 1 x 2 SMZ switch with a high contrast ratio
Abstract — An all-optical 1×2 high contrast ratio (CR) switch based on the symmetric Mach-Zehnder (SMZ) interferometers is presented. Simulation results show a remarkable improvement of the inter-output CR (~25 dB) between the two outputs compared with an existing SMZ switch. It is shown that the proposed switch offers high values of inter-output CR (> 32dB) over a wide range of input powers using appropriate power of the control pulses. I
Multi-particle quantum walks in one-dimensional lattice
Quantum walk is a counterpart of classical random walk in the quantum regime
that exhibits non-classical behaviors and outperforms classical random walk in
various aspects. It has been known that the spatial probability distribution of
a single-particle quantum walk can expand quadratically in time while a
single-particle classical random walk can do only linearly. In this paper, we
analytically study the discrete-time quantum walk of non-interacting multiple
particles in a one-dimensional infinite lattice, and investigate the role of
entanglement and exchange symmetry in the position distribution of the
particles during the quantum walk. To analyze the position distribution of
multi-particle quantum walk, we consider the relative distance between
particles, and study how it changes with the number of walk steps. We compute
the relative distance asymptotically for a large number of walk steps and find
that the distance increases quadratically with the number of walk steps. We
also study the extremal relative distances between the particles, and show the
role of the exchange symmetry of the initial state in the distribution of the
particles. Our study further shows the dependence of two-particle correlations,
two-particle position distributions on the exchange symmetry, and find
exponential decrement of the entanglement of the extremal state with the number
of particles
Distributed Optimal Frequency Control Considering a Nonlinear Network-Preserving Model
This paper addresses the distributed optimal frequency control of power
systems considering a network-preserving model with nonlinear power flows and
excitation voltage dynamics. Salient features of the proposed distributed
control strategy are fourfold: i) nonlinearity is considered to cope with large
disturbances; ii) only a part of generators are controllable; iii) no load
measurement is required; iv) communication connectivity is required only for
the controllable generators. To this end, benefiting from the concept of
'virtual load demand', we first design the distributed controller for the
controllable generators by leveraging the primal-dual decomposition technique.
We then propose a method to estimate the virtual load demand of each
controllable generator based on local frequencies. We derive incremental
passivity conditions for the uncontrollable generators. Finally, we prove that
the closed-loop system is asymptotically stable and its equilibrium attains the
optimal solution to the associated economic dispatch problem. Simulations,
including small and large-disturbance scenarios, are carried on the New England
system, demonstrating the effectiveness of our design
The NN phase shifts in the extended quark-delocalization, color-screening model
An alternative method is applied to the study of nucleon-nucleon(NN)
scattering phase shifts in the framework of extended quark delocalization,
color-screening model(QDCSM), where the one-pion-exchange(OPE) with short-range
cutoff is included.Comment: 5 pages, 3 figures, two-colum
Optimisation of the key SOA parameters for amplification and switching
Wireless Sensor Networks (WSN) are composed of small, low cost, resource-constrained computing nodes equipped with low power wireless transceivers. Generally, they are embedded in their environment to perform some specific monitoring and/or control function. Unlike wired networks that have dedicated routers for network connectivity and message forwarding, every node in a WSN can act as a router in a multi-hop network. A WSN can offer a cheap, applicationspecific solution in a variety of situations including military and disaster response scenarios, where other approaches are not viable. Due to their unattended nature and deployment in possibly hostile environmental conditions, there are many challenges in ensuring that a WSN is formed effectively and survives long enough to fulfil its function. Securing a WSN against attack is a particular challenge. Traditional encryption mechanisms are resource hungry and are not sufficient alone to provide a complete solution. This project is concerned with secure routing protocols. Formal methods are used to model and analyse the design of existing protocols and to demonstrate some previously unreported weaknesses
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