6,235 research outputs found
Entanglement generation via a completely mixed nuclear spin bath
We show that qubits coupled sequentially to a mesoscopic static completely
mixed spin bath via the Heisenberg interaction can become highly entangled.
Straightforward protocols for the generation of multipartite entangled
(Greenberger-Horne-Zeilinger-)states are presented. We show the feasibility of
an experimental realization in a quantum dot by the hyperfine interaction of an
electron with the nuclear spins.Comment: 4+pages, 3 figure
Pure single photon generation by type-I PDC with backward-wave amplification
We explore a promising method of generating pure heralded single photons. Our
approach is based on parametric downconversion in a periodically-poled
waveguide. However, unlike conventional downconversion sources, the photon
pairs are counter-propagating: one travels with the pump beam in the forward
direction while the other is backpropagating towards the laser source. Our
calculations reveal that these downconverted two-photon states carry minimal
spectral correlations within each photon-pair. This approach offers the
possibility to employ a new range of downconversion processes and materials
like PPLN (previously considered unsuitable due to their unfavorable
phasematching properties) to herald pure single photons over a broad frequency
range.Comment: 8 pages, 3 figures, minor text changes and reformattin
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The Warburg effect and its role in cancer detection and therapy
The Warburg effect is a cellular phenomenon in cancer cells discovered by Otto Warburg in 1924. His findings showed that in normoxic conditions tumor cells primarily use glycolysis for energy production instead of mitochondrial oxidative phosphorylation like normal cells. This breakthrough has been the basis for much research. It has resulted in a successful and widely-used cancer detection method, the positron emission tomography (PET) scan. The PET scan uses radioactive isotopes and the fact that cancer cells exhibit higher rates of glycolysis to pinpoint tumors with advanced imaging tools. Furthermore, Warburg's work helped to show the potential for beneficial pharmaceuticals that could be developed by inhibiting certain chemical mechanisms of glycolysis to specifically target and kill cancer cells. This review covers research that has used the Warburg effect as a premise and the heretofore indications and applications of the Warburg effect
Simplicial Quantum Gravity on a Computer
We describe a method of Monte-Carlo simulations of simplicial quantum gravity
coupled to matter fields. We concentrate mainly on the problem of implementing
effectively the random, dynamical triangulation and building in a
detailed-balance condition into the elementary transformations of the
triangulation. We propose a method of auto-tuning the parameters needed to
balance simulations of the canonical ensemble. This method allows us to prepare
a whole set of jobs and therefore is very useful in systematic determining the
phase diagram in two dimensional coupling space. It is of particular importance
when the jobs are run on a parallel machine.Comment: 24 pages, PostScrip
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Deliverable 6.1: Radio spectrum, traffic engineering and resource management
Weakly Equivalent Arrays
The (extensional) theory of arrays is widely used to model systems. Hence,
efficient decision procedures are needed to model check such systems. Current
decision procedures for the theory of arrays saturate the read-over-write and
extensionality axioms originally proposed by McCarthy. Various filters are used
to limit the number of axiom instantiations while preserving completeness. We
present an algorithm that lazily instantiates lemmas based on weak equivalence
classes. These lemmas are easier to interpolate as they only contain existing
terms. We formally define weak equivalence and show correctness of the
resulting decision procedure
decays and twisted boundary conditions
We propose a new method to evaluate the Lellouch-L\"uscher factor which
relates the matrix elements computed on a finite
lattice to the physical (infinite-volume) decay amplitudes. The method relies
on the use of partially twisted boundary conditions, which allow the s-wave
phase shift to be computed as an almost continuous function of the
centre-of-mass relative momentum and hence for its derivative to be evaluated.
We successfully demonstrate the feasibility of the technique in an exploratory
computation.Comment: 19 pages, 7 figure
Evidence for a Critical Behavior in Pure Compact QED
We present evidence about a critical behavior of compact QED (CQED) pure
gauge theory. Regularizing the theory on lattices homotopic to a sphere, we
present evidence for a critical, i.e. second order like behavior at the
deconfinement phase transition for certain values of the coupling parameter
.Comment: 3 pages, 3 figures, POSTSCRIPT file (127KB uuencoded
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