70,752 research outputs found
The effects of disorder and interactions on the Anderson transition in doped Graphene
We undertake an exact numerical study of the effects of disorder on the
Anderson localization of electronic states in graphene. Analyzing the scaling
behaviors of inverse participation ratio and geometrically averaged density of
states, we find that Anderson metal-insulator transition can be introduced by
the presence of quenched random disorder. In contrast with the conventional
picture of localization, four mobility edges can be observed for the honeycomb
lattice with specific disorder strength and impurity concentration. Considering
the screening effects of interactions on disorder potentials, the experimental
findings of the scale enlarges of puddles can be explained by reviewing the
effects of both interactions and disorder.Comment: 7 pages, 7 figure
Effect of excited states and applied magnetic fields on the measured hole mobility in an organic semiconductor
Copyright 2010 by the American Physical Society. Article is available at
Quantum information storage and state transfer based on spin systems
The idea of quantum state storage is generalized to describe the coherent
transfer of quantum information through a coherent data bus. In this universal
framework, we comprehensively review our recent systematical investigations to
explore the possibility of implementing the physical processes of quantum
information storage and state transfer by using quantum spin systems, which may
be an isotropic antiferromagnetic spin ladder system or a ferromagnetic
Heisenberg spin chain. Our studies emphasize the physical mechanisms and the
fundamental problems behind the various protocols for the storage and transfer
of quantum information in solid state systems.Comment: 11 pages, 9 figures, Review article on the quantum spin based quantum
information processing, to appear the special issue of Low Temperature
Physics dedicated to the 70-th anniversary of creation of concept
"antiferromagnetism" in physics of magnetis
Quantum Communication through Spin Chain Dynamics: an Introductory Overview
We present an introductory overview of the use of spin chains as quantum
wires, which has recently developed into a topic of lively interest. The
principal motivation is in connecting quantum registers without resorting to
optics. A spin chain is a permanently coupled 1D system of spins. When one
places a quantum state on one end of it, the state will be dynamically
transmitted to the other end with some efficiency if the spins are coupled by
an exchange interaction. No external modulations or measurements on the body of
the chain, except perhaps at the very ends, is required for this purpose. For
the simplest (uniformly coupled) chain and the simplest encoding (single qubit
encoding), however, dispersion reduces the quality of transfer. We present a
variety of alternatives proposed by various groups to achieve perfect quantum
state transfer through spin chains. We conclude with a brief discussion of the
various directions in which the topic is developing.Comment: Material covered till Dec 200
Self-management of context-aware overlay ambient networks
Ambient Networks (ANs) are dynamically changing and heterogeneous as they consist of potentially large numbers of independent, heterogeneous mobile nodes, with spontaneous topologies that can logically interact with each other to share a common control space, known as the Ambient Control Space. ANs are also flexible i.e. they can compose and decompose dynamically and automatically, for supporting the deployment of cross-domain (new) services. Thus, the AN architecture must be sophisticatedly designed to support such high level of dynamicity, heterogeneity and flexibility. We advocate the use of service specific overlay networks in ANs, that are created on-demand according to specific service requirements, to deliver, and to automatically adapt services to the dynamically changing user and network context. This paper presents a self-management approach to create, configure, adapt, contextualise, and finally teardown service specific overlay networks
Using domain models for context-rich user logging
This paper describes the prototype interactive search sys- Tem being developed within the AutoAdapt project1. The AutoAdapt project seeks to enhance the user experience in searching for information and navigating within selected do- main collections by providing structured representations of domain knowledge to be directly explored, logged, adapted and updated to refject user needs. We propose that this structure is a valuable stepping-stone in context-rich logging of user activities within the information seeking environment. Here we describe the primary components that have been implemented and the user interactions that it will support
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