60 research outputs found
Nonlinear resonant behavior of the dispersive readout scheme for a superconducting flux qubit
A nonlinear resonant circuit comprising a SQUID magnetometer and a parallel
capacitor is studied as a readout scheme for a persistent-current (PC) qubit.
The flux state of the qubit is detected as a change in the Josephson inductance
of the SQUID magnetometer, which in turn mediates a shift in the resonance
frequency of the readout circuit. The nonlinearity and resulting hysteresis in
the resonant behavior are characterized as a function of the power of both the
input drive and the associated resonance peak response. Numerical simulations
based on a phenomenological circuit model are presented which display the
features of the observed nonlinearity.Comment: 9 pages, 9 figure
Managing Dynamic User Communities in a Grid of Autonomous Resources
One of the fundamental concepts in Grid computing is the creation of Virtual
Organizations (VO's): a set of resource consumers and providers that join
forces to solve a common problem. Typical examples of Virtual Organizations
include collaborations formed around the Large Hadron Collider (LHC)
experiments. To date, Grid computing has been applied on a relatively small
scale, linking dozens of users to a dozen resources, and management of these
VO's was a largely manual operation. With the advance of large collaboration,
linking more than 10000 users with a 1000 sites in 150 counties, a
comprehensive, automated management system is required. It should be simple
enough not to deter users, while at the same time ensuring local site autonomy.
The VO Management Service (VOMS), developed by the EU DataGrid and DataTAG
projects[1, 2], is a secured system for managing authorization for users and
resources in virtual organizations. It extends the existing Grid Security
Infrastructure[3] architecture with embedded VO affiliation assertions that can
be independently verified by all VO members and resource providers. Within the
EU DataGrid project, Grid services for job submission, file- and database
access are being equipped with fine- grained authorization systems that take VO
membership into account. These also give resource owners the ability to ensure
site security and enforce local access policies. This paper will describe the
EU DataGrid security architecture, the VO membership service and the local site
enforcement mechanisms Local Centre Authorization Service (LCAS), Local
Credential Mapping Service(LCMAPS) and the Java Trust and Authorization
Manager.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 7 pages, LaTeX, 5 eps figures. PSN
TUBT00
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