1,903 research outputs found
Mixed state geometric phases, entangled systems, and local unitary transformations
The geometric phase for a pure quantal state undergoing an arbitrary
evolution is a ``memory'' of the geometry of the path in the projective Hilbert
space of the system. We find that Uhlmann's geometric phase for a mixed quantal
state undergoing unitary evolution not only depends on the geometry of the path
of the system alone but also on a constrained bi-local unitary evolution of the
purified entangled state. We analyze this in general, illustrate it for the
qubit case, and propose an experiment to test this effect. We also show that
the mixed state geometric phase proposed recently in the context of
interferometry requires uni-local transformations and is therefore essentially
a property of the system alone.Comment: minor changes, journal reference adde
Modified sorting technique to mitigate the collateral mortality of trawled school prawns (Metapenaeus macleayi)
The potential for changes to onboard handling practices in order to improve the fate of juvenile school prawns (Metapenaeus macleayi) discarded during trawling were investigated in two Australian rivers (Clarence and Hunter) by comparing a purpose-built, water-filled sorting tray against a conventional dry tray across various conditions, including the range of typical delays before the start of sorting the catch (2 min vs. 15 min). Juvenile school prawns
(n= 5760), caught during 32 and 16 deployments in each river, were caged and sacrificed at four times: immediately
(T0), and at 24 (T24), 72 (T72), and 120 (T12 0) hours after having been discarded. In both rivers, most
mortalities occurred between T0 and T24 and, after adjusting for control deaths (<12%), were greatest for the
15-min conventional treatment (up to 41% at T120). Mixed-effects logistic models revealed that in addition to the sampling time, method of sorting, and delay in sorting, the weight of the catch, salinity, and percentage cloud cover were significant predictors of mortality. Although trawling
caused some mortalities and comparable stress (measured as L -lactate) in all school prawns, use of the water tray lessened the negative impacts of some of the above factors across both the 2-min and 15-min delays in sorting so that the overall discard mortality was reduced by more than a
third. When used in conjunction with selective trawls, widespread application of the water tray should help to
improve the sustainability of trawling for school prawns
Probability distributions consistent with a mixed state
A density matrix may be represented in many different ways as a
mixture of pure states, \rho = \sum_i p_i |\psi_i\ra \la \psi_i|. This paper
characterizes the class of probability distributions that may appear in
such a decomposition, for a fixed density matrix . Several illustrative
applications of this result to quantum mechanics and quantum information theory
are given.Comment: 6 pages, submitted to Physical Review
The FilmTech experience
Project Leaders: Roger Cook, Jeffrey UhlmannFormal proposal for the 2008/2009 project, "The FilmTech Experience." From original description: "This project brings together students and faculty from several departments and programs in three different colleges, as well as staff from the Missouri Film Office and Student Life to work collaboratively on a feature film project. The filmmaking venture will enable students to use cutting-edge information technology on a competitive industry project and to gain professional experience and credits in the entertainment field. It will also open up new interdisciplinary areas of curriculum, both in the various major fields and with the new Film Production course that will be offered in Spring 2009 in conjunction with the project."MU Interdisciplinary Innovations Fun
Continuous variable remote state preparation
We extend exact deterministic remote state preparation (RSP) with minimal
classical communication to quantum systems of continuous variables. We show
that, in principle, it is possible to remotely prepare states of an ensemble
that is parameterized by infinitely many real numbers, i.e., by a real
function, while the classical communication cost is one real number only. We
demonstrate continuous variable RSP in three examples using (i) quadrature
measurement and phase space displacement operations, (ii) measurement of the
optical phase and unitaries shifting the same, and (iii) photon counting and
photon number shift.Comment: 7 pages, RevTeX
Investigation into Energy Efficiency of Outdated Cutting Machine Tools and Identification of Improvement Potentials to Promote Sustainability
AbstractCutting machine tools have a significant impact on manufacturing and sustainability. There exist a large number of outdated cutting machine tools especially in developing and emerging countries which are still taking a considerable share in global value creation. Furthermore, an increasing trend in field of reuse, retrofitting and upgrading can be observed. For Life-Cycle-Assessment and analyses of end-of-life behavior of such machine tools in context of sustainability, reliable values for energy consumption and machining efficiency under realistic machining conditions are indispensable. In the present paper the energy consumption and machining efficiency of an exemplary outdated milling machine have been measured and analyzed under consideration of different influences such as process parameter, machining material and ratio of prim time to secondary time. Additionally a comparison between a newer and the outdated milling machine has been carried out in order to identify and quantify possible improvement potentials of outdated machine tool concerning energy consumption and machining efficiency. Based on obtained results more accurate and realistic decision can be made by enterprises who aim to promote sustainable manufacturing
Conserved features of cohesin binding along fission yeast chromosomes
High-resolution analysis of cohesin localization on fission yeast chromosomes reveals that several determinants, previously thought to be organism-specific, come together to shape overall distribution
Cutting simulation with consideration of the material hardening in the Shear Zone of AISI1045
By the use of high energy synchrotron X-ray diffraction it was possible to determine the stress state in the chip formation zone during orthogonal cutting of AISI1045. The analysis of the diffractograms showed a hardening of the material during the movement through the shear zone. For this reason nano indentation experiments on prepared chips have been carried out. With these experiments, the material hardening has been confirmed. The nano indentation experiments were reproduced by FEM simulations and it was possible to determine flow curves of the hardened material above the shear zone based on existing flow curves of AISI1045. Thus, cutting simulations have been carried out, which considered the material hardening in the shear zone. The simulation results were then compared with the results of the in-situ strain measurements
Operational approach to the Uhlmann holonomy
We suggest a physical interpretation of the Uhlmann amplitude of a density
operator. Given this interpretation we propose an operational approach to
obtain the Uhlmann condition for parallelity. This allows us to realize
parallel transport along a sequence of density operators by an iterative
preparation procedure. At the final step the resulting Uhlmann holonomy can be
determined via interferometric measurements.Comment: Added material, references, and journal reference
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