124 research outputs found
Effective Hamiltonian Theory and Its Applications in Quantum Information
This paper presents a useful compact formula for deriving an effective
Hamiltonian describing the time-averaged dynamics of detuned quantum systems.
The formalism also works for ensemble-averaged dynamics of stochastic systems.
To illustrate the technique we give examples involving Raman processes,
Bloch-Siegert shifts and Quantum Logic Gates.Comment: 5 pages, 3 figures, to be published in Canadian Journal of Physic
The Three-Magnon Contribution to the Spin Correlation Function in Integer-Spin Antiferromagnetic Chains
The exact form factor for the O(3) non-linear sigma model is used to predict
the three-magnon contribution to the spin correlation function, S(q,w), near
wavevector q=pi in an integer spin, one-dimensional antiferromagnet. The
three-magnon contribution is extrememly broad and extremely weak; the
integrated intensity is <2% of the single-magnon contribution.Comment: 4 pages, 1 figur
Evaluation Codes from smooth Quadric Surfaces and Twisted Segre Varieties
We give the parameters of any evaluation code on a smooth quadric surface.
For hyperbolic quadrics the approach uses elementary results on product codes
and the parameters of codes on elliptic quadrics are obtained by detecting a
BCH structure of these codes and using the BCH bound. The elliptic quadric is a
twist of the surface P^1 x P^1 and we detect a similar BCH structure on twists
of the Segre embedding of a product of any d copies of the projective line.Comment: 10 pages. Presented at the conference Workshop on Coding theory and
Cryptography 201
Directed geometrical worm algorithm applied to the quantum rotor model
We discuss the implementation of a directed geometrical worm algorithm for
the study of quantum link-current models. In this algorithm Monte Carlo updates
are made through the biased reptation of a worm through the lattice. A directed
algorithm is an algorithm where, during the construction of the worm, the
probability for erasing the immediately preceding part of the worm, when adding
a new part,is minimal. We introduce a simple numerical procedure for minimizing
this probability. The procedure only depends on appropriately defined local
probabilities and should be generally applicable. Furthermore we show how
correlation functions, C(r,tau) can be straightforwardly obtained from the
probability of a worm to reach a site (r,tau) away from its starting point
independent of whether or not a directed version of the algorithm is used.
Detailed analytical proofs of the validity of the Monte Carlo algorithms are
presented for both the directed and un-directed geometrical worm algorithms.
Results for auto-correlation times and Green functions are presented for the
quantum rotor model.Comment: 11 pages, 9 figures, v2 : Additional results and data calculated at
an incorrect chemical potential replaced. Conclusions unchange
Dispersive Manipulation of Paired Superconducting Qubits
We combine the ideas of qubit encoding and dispersive dynamics to enable
robust and easy quantum information processing (QIP) on paired superconducting
charge boxes sharing a common bias lead. We establish a decoherence free
subspace on these and introduce universal gates by dispersive interaction with
a LC resonator and inductive couplings between the encoded qubits. These gates
preserve the code space and only require the established local symmetry and the
control of the voltage bias.Comment: 5 pages, incl. 1 figur
Description of the CEEH integrated "Energy-Environment-Health-Cost" modelling franework system
100 ancient genomes show repeated population turnovers in Neolithic Denmark.
Major migration events in Holocene Eurasia have been characterized genetically at broad regional scales <sup>1-4</sup> . However, insights into the population dynamics in the contact zones are hampered by a lack of ancient genomic data sampled at high spatiotemporal resolution <sup>5-7</sup> . Here, to address this, we analysed shotgun-sequenced genomes from 100 skeletons spanning 7,300 years of the Mesolithic period, Neolithic period and Early Bronze Age in Denmark and integrated these with proxies for diet ( <sup>13</sup> C and <sup>15</sup> N content), mobility ( <sup>87</sup> Sr/ <sup>86</sup> Sr ratio) and vegetation cover (pollen). We observe that Danish Mesolithic individuals of the Maglemose, Kongemose and Ertebølle cultures form a distinct genetic cluster related to other Western European hunter-gatherers. Despite shifts in material culture they displayed genetic homogeneity from around 10,500 to 5,900 calibrated years before present, when Neolithic farmers with Anatolian-derived ancestry arrived. Although the Neolithic transition was delayed by more than a millennium relative to Central Europe, it was very abrupt and resulted in a population turnover with limited genetic contribution from local hunter-gatherers. The succeeding Neolithic population, associated with the Funnel Beaker culture, persisted for only about 1,000 years before immigrants with eastern Steppe-derived ancestry arrived. This second and equally rapid population replacement gave rise to the Single Grave culture with an ancestry profile more similar to present-day Danes. In our multiproxy dataset, these major demographic events are manifested as parallel shifts in genotype, phenotype, diet and land use
A new mathematical model for combining growth and energy intake in animals: The case of the growing pig
Modeling Translation in Protein Synthesis with TASEP: A Tutorial and Recent Developments
The phenomenon of protein synthesis has been modeled in terms of totally
asymmetric simple exclusion processes (TASEP) since 1968. In this article, we
provide a tutorial of the biological and mathematical aspects of this approach.
We also summarize several new results, concerned with limited resources in the
cell and simple estimates for the current (protein production rate) of a TASEP
with inhomogeneous hopping rates, reflecting the characteristics of real genes.Comment: 25 pages, 7 figure
Integrated Brain Atlas for Unbiased Mapping of Nervous System Effects Following Liraglutide Treatment
Light Sheet Fluorescence Microscopy (LSFM) of whole organs, in particular the brain, offers a plethora of biological data imaged in 3D. This technique is however often hindered by cumbersome non-Automated analysis methods. Here we describe an approach to fully automate the analysis by integrating with data from the Allen Institute of Brain Science (AIBS), to provide precise assessment of the distribution and action of peptide-based pharmaceuticals in the brain. To illustrate this approach, we examined the acute central nervous system effects of the glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide. Peripherally administered liraglutide accessed the hypothalamus and brainstem, and led to activation in several brain regions of which most were intersected
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