Disentanglement by Dissipative Open System Dynamics

This paper investigates disentanglement as a result of evolution according to a class of master equations which include dissipation and interparticle interactions. Generalizing an earlier result of Di\'{o}si, the time taken for complete disentanglement is calculated (i.e. for disentanglement from any other system). The dynamics of two harmonically coupled oscillators is solved in order to study the competing effects of environmental noise and interparticle coupling on disentanglement. An argument based on separability conditions for gaussian states is used to arrive at a set of conditions on the couplings sufficient for all initial states to disentangle for good after a finite time.Comment: Paper in conjunction with and following on from P.J. Dodd and J.J. Halliwell: quant-ph/031206

Non-equilibrium entangled steady state of two independent two-level systems

We determine and study the steady state of two independent two-level systems weakly coupled to a stationary non-equilibrium environment. Whereas this bipartite state is necessarily uncorrelated if the splitting energies of the two-level systems are different from each other, it can be entangled if they are equal. For identical two-level systems interacting with two bosonic heat baths at different temperatures, we discuss the influence of the baths temperatures and coupling parameters on their entanglement. Geometric properties, such as the baths dimensionalities and the distance between the two-level systems, are relevant. A regime is found where the steady state is a statistical mixture of the product ground state and of the entangled singlet state with respective weights 2/3 and 1/3

Fast Non-Adiabatic Two Qubit Gates for the Kane Quantum Computer

In this paper we apply the canonical decomposition of two qubit unitaries to find pulse schemes to control the proposed Kane quantum computer. We explicitly find pulse sequences for the CNOT, swap, square root of swap and controlled Z rotations. We analyze the speed and fidelity of these gates, both of which compare favorably to existing schemes. The pulse sequences presented in this paper are theoretically faster, higher fidelity, and simpler than existing schemes. Any two qubit gate may be easily found and implemented using similar pulse sequences. Numerical simulation is used to verify the accuracy of each pulse scheme

Entanglement, Bell Inequalities and Decoherence in Particle Physics

We demonstrate the relevance of entanglement, Bell inequalities and decoherence in particle physics. In particular, we study in detail the features of the ``strange'' $K^0 \bar K^0$ system as an example of entangled meson--antimeson systems. The analogies and differences to entangled spin--1/2 or photon systems are worked, the effects of a unitary time evolution of the meson system is demonstrated explicitly. After an introduction we present several types of Bell inequalities and show a remarkable connection to CP violation. We investigate the stability of entangled quantum systems pursuing the question how possible decoherence might arise due to the interaction of the system with its ``environment''. The decoherence is strikingly connected to the entanglement loss of common entanglement measures. Finally, some outlook of the field is presented.Comment: Lectures given at Quantum Coherence in Matter: from Quarks to Solids, 42. Internationale Universit\"atswochen f\"ur Theoretische Physik, Schladming, Austria, Feb. 28 -- March 6, 2004, submitted to Lecture Notes in Physics, Springer Verlag, 45 page

The cost-effectiveness of providing antenatal lifestyle advice for women who are overweight or obese: the LIMIT randomised trial

BACKGROUND: Overweight and obesity during pregnancy is common, although robust evidence about the economic implications of providing an antenatal dietary and lifestyle intervention for women who are overweight or obese is lacking. We conducted a health economic evaluation in parallel with the LIMIT randomised trial. Women with a singleton pregnancy, between 10(+0)-20(+0) weeks, and BMI ≥25 kg/m(2) were randomised to Lifestyle Advice (a comprehensive antenatal dietary and lifestyle intervention) or Standard Care. The economic evaluation took the perspective of the health care system and its patients, and compared costs encountered from the additional use of resources from time of randomisation until six weeks postpartum. Increments in health outcomes for both the woman and infant were considered in the cost-effectiveness analysis. Mean costs and effects in the treatment groups allocated at randomisation were compared, and incremental cost effectiveness ratios (ICERs) and confidence intervals (95%) calculated. Bootstrapping was used to confirm the estimated confidence intervals, and to generate acceptability curves representing the probability of the intervention being cost-effective at alternative monetary equivalent values for the outcomes avoiding high infant birth weight, and respiratory distress syndrome. Analyses utilised intention to treat principles. RESULTS: Overall, the increase in mean costs associated with providing the intervention was offset by savings associated with improved immediate neonatal outcomes, rendering the intervention cost neutral (Lifestyle Advice Group $11261.19±$14573.97 versus Standard Care Group $11306.70±$14562.02; p=0.094). Using a monetary value of $20,000 as a threshold value for avoiding an additional infant with birth weight above 4 kg, the probability that the antenatal intervention is cost-effective is 0.85, which increases to 0.95 when the threshold monetary value increases to$45,000. CONCLUSIONS: Providing an antenatal dietary and lifestyle intervention for pregnant women who are overweight or obese is not associated with increased costs or cost savings, but is associated with a high probability of cost effectiveness. Ongoing participant follow-up into childhood is required to determine the medium to long-term impact of the observed, short-term endpoints, to more accurately estimate the value of the intervention on risk of obesity, and associated costs and health outcomes. TRIALS REGISTRATION: Australian and New Zealand Clinical Trials Registry (ACTRN12607000161426).Jodie M Dodd, Sharmina Ahmed, Jonathan Karnon, Wendy Umberger, Andrea R Deussen, Thach Tran, Rosalie M Grivell, Caroline A Crowther, Deborah Turnbull, Andrew J McPhee, Gary Wittert, Julie A Owens, Jeffrey S Robinson and For the LIMIT Randomised Trial Grou

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Terrestrial habitat requirements of nesting freshwater turtles

Because particular life history traits affect species vulnerability to development pressures, cross-species summaries of life history traits are useful for generating management guidelines. Conservation of aquatic turtles, many members of which are regionally or globally imperiled, requires knowing the extent of upland habitat used for nesting. Therefore, we compiled distances that nests and gravid females had been observed from wetlands. Based on records of \u3e 8000 nests and gravid female records compiled for 31 species in the United States and Canada, the distances that encompass 95% of nests vary dramatically among genera and populations, from just 8 m for Malaclemys to nearly 1400 m for Trachemys. Widths of core areas to encompass varying fractions of nesting populations (based on mean maxima across all genera) were estimated as: 50% coverage = 93 m, 75% = 154 m, 90% = 198 m, 95% = 232 m, 100% = 942 m. Approximately 6–98 m is required to encompass each consecutive 10% segment of a nesting population up to 90% coverage; thereafter, ca. 424 m is required to encompass the remaining 10%. Many genera require modest terrestrial areas (\u3c200 m zones) for 95% nest coverage (Actinemys, Apalone, Chelydra, Chrysemys, Clemmys, Glyptemys, Graptemys, Macrochelys, Malaclemys, Pseudemys, Sternotherus), whereas other genera require larger zones (Deirochelys, Emydoidea, Kinosternon, Trachemys). Our results represent planning targets for conserving sufficient areas of uplands around wetlands to ensure protection of turtle nesting sites, migrating adult female turtles, and dispersing turtle hatchlings

Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV

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