525 research outputs found
Quantum Holonomies in (2+1)-Dimensional Gravity
We describe an approach to the quantization of (2+1)--dimensional gravity
with topology R x T^2 and negative cosmological constant, which uses two
quantum holonomy matrices satisfying a q--commutation relation. Solutions of
diagonal and upper--triangular form are constructed, which in the latter case
exhibit additional, non--trivial internal relations for each holonomy matrix.
This leads to the notion of quantum matrix pairs. These are pairs of matrices
with non-commuting entries, which have the same pattern of internal relations,
q-commute with each other under matrix multiplication, and are such that
products of powers of the matrices obey the same pattern of internal relations
as the original pair. This has implications for the classical moduli space,
described by ordered pairs of commuting SL(2,R) matrices modulo simultaneous
conjugation by SL(2,R) matrices.Comment: 5 pages, to appear in the proceedings of 10th Marcel Grossmann
Meeting on Recent Developments in Theoretical and Experimental General
Relativity, Gravitation and Relativistic Field Theories (MG X MMIII), Rio de
Janeiro, Brazil, 20-26 Jul 200
Single Atom Imaging with an sCMOS camera
Single atom imaging requires discrimination of weak photon count events above
background and has typically been performed using either EMCCD cameras,
photomultiplier tubes or single photon counting modules. sCMOS provides a cost
effective and highly scalable alternative to other single atom imaging
technologies, offering fast readout and larger sensor dimensions. We
demonstrate single atom resolved imaging of two site-addressable single atom
traps separated by 10~m using an sCMOS camera, offering a competitive
signal-to-noise ratio at intermediate count rates to allow high fidelity
readout discrimination (error ) and sub-m spatial resolution for
applications in quantum technologies.Comment: 4 pages, 4 figure
Quantum Geometry and Quantum Gravity
The purpose of this contribution is to give an introduction to quantum
geometry and loop quantum gravity for a wide audience of both physicists and
mathematicians. From a physical point of view the emphasis will be on
conceptual issues concerning the relationship of the formalism with other more
traditional approaches inspired in the treatment of the fundamental
interactions in the standard model. Mathematically I will pay special attention
to functional analytic issues, the construction of the relevant Hilbert spaces
and the definition and properties of geometric operators: areas and volumes.Comment: To appear in the AIP Conference Proceedings of the XVI International
Fall Workshop on Geometry and Physics, Lisbon - Portugal, 5-8 September 200
Parasupersymmetric Quantum Mechanics of Order 3 and a Generalized Witten Index
In this paper we generalize the Rubakov-Spiridonov parasupersymmetry algebra
to the order 3 case. We also generalize the notion of the Witten index, and we
provide a class of models satisfying our parasupersymmetry algebra. Finally, we
show that there is a correspondence between the Hamiltonian and the index in
our class of models
Stakeholder involvement in wastewater treatment design
The design option appraisal stage of new water industry capital investment projects involve greater levels of complexity than those generally encountered in other stages of the design process. It is at this stage that the issues related to sustainable development will be introduced, as decisions are multi-stakeholder and therefore decision criteria that reflect the views of a wide range of stakeholders with a range of different viewpoints need to be incorporated. This paper describes a case study which maps information flows, identifies decision criteria and evaluates the extent of stakeholder involvement in the design stage of a major UK wastewater system project. A mapping technique was developed to document and represent the flow of information during the decision making process. An in-depth study of the information flows enabled the researchers to establish the extent to which sustainability criteria were actually used. This was compared with recognised sustainability criteria identified in previous research involving the authors to allow an assessment of the effectiveness of stakeholder representation. Recommendations are given regarding ways of improving stakeholder involvement in water industry asset investment decisions
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