Britain and the Bomb: Nuclear Diplomacy, 1964- 1970 (Book Review) by David James Gill

Review of Britain and the Bomb: Nuclear Diplomacy, 1964- 1970 by David James Gill

Item weighted Kemeny distance for preference data

Preference data represent a particular type of ranking data where a group of people gives their preferences over a set of alternatives. The traditional metrics between rankings don’t take into account that the importance of elements can be not uniform. In this paper the item weighted Kemeny distance is introduced and its properties demonstrated

Towards a unified approach to information-disturbance tradeoffs in quantum measurements

We show that the global balance of information dynamics for general quantum measurements given in [F. Buscemi, M. Hayashi, and M. Horodecki, Phys.Rev.Lett. 100, 210504 (2008)] makes it possible to unify various and generally inequivalent approaches adopted in order to derive information-disturbance tradeoffs in quantum theory. We focus in particular on those tradeoffs, constituting the vast majority of the literature on the subject, where disturbance is defined either in terms of average output fidelity or of entanglement fidelity

Britain and the Bomb: Nuclear Diplomacy, 1964- 1970 (Book Review) by David James Gill

Review of Britain and the Bomb: Nuclear Diplomacy, 1964- 1970 by David James Gill

Dynamics of quantum correlations in colored environments

We address the dynamics of entanglement and quantum discord for two non interacting qubits initially prepared in a maximally entangled state and then subjected to a classical colored noise, i.e. coupled with an external environment characterized by a noise spectrum of the form $1/f^{\alpha}$. More specifically, we address systems where the Gaussian approximation fails, i.e. the sole knowledge of the spectrum is not enough to determine the dynamics of quantum correlations. We thus investigate the dynamics for two different configurations of the environment: in the first case the noise spectrum is due to the interaction of each qubit with a single bistable fluctuator with an undetermined switching rate, whereas in the second case we consider a collection of classical fluctuators with fixed switching rates. In both cases we found analytical expressions for the time dependence of entanglement and quantum discord, which may be also extended to a collection of flcutuators with random switching rates. The environmental noise is introduced by means of stochastic time-dependent terms in the Hamiltonian and this allows us to describe the effects of both separate and common environments. We show that the non-Gaussian character of the noise may lead to significant effects, e.g. environments with the same power spectrum, but different configurations, give raise to opposite behavior for the quantum correlations. In particular, depending on the characteristics of the environmental noise considered, both entanglement and discord display either a monotonic decay or the phenomena of sudden death and revivals. Our results show that the microscopic structure of environment, besides its noise spectrum, is relevant for the dynamics of quantum correlations, and may be a valid starting point for the engineering of non-Gaussian colored environments.Comment: 8 pages, 3 figure

Non-Markovian continuous-time quantum walks on lattices with dynamical noise

We address the dynamics of continuous-time quantum walks on one-dimensional disordered lattices inducing dynamical noise in the system. Noise is described as time-dependent fluctuations of the tunneling amplitudes between adjacent sites, and attention is focused on non-Gaussian telegraph noise, going beyond the usual assumption of fast Gaussian noise. We observe the emergence of two different dynamical behaviors for the walker, corresponding to two opposite noise regimes: slow noise (i.e. strong coupling with the environment) confines the walker into few lattice nodes, while fast noise (weak coupling) induces a transition between quantum and classical diffusion over the lattice. A phase transition between the two dynamical regimes may be observed by tuning the ratio between the autocorrelation time of the noise and the coupling between the walker and the external environment generating the noise. We also address the non-Markovianity of the quantum map by assessing its memory effects, as well as evaluating the information backflow to the system. Our results suggest that the non-Markovian character of the evolution is linked to the dynamical behavior in the slow noise regime, and that fast noise induces a Markovian dynamics for the walker.Comment: 10 pages, 8 figure

Perioperative and anesthetic deaths: toxicological and medico legal aspects

Background: Anesthesia has become safer during decades, though there is still a preventable mortality; the complexity of medical and surgical interventions, increasingly older and sicker patients, has created a host of new hazards in anesthesiology. In this paper, some of these perioperative (PO) fatal adverse events are investigated in terms of health responsibility. Selective literature research in several data bases, concerning perioperative and anesthetic deaths and medical responsibility, was performed. Main text: A generally accepted definition of the anesthesia and perioperatory-related death still remains one of the major concerns in forensic pathology, and the terms “operative deaths” and “anesthetic deaths” are usually applied inaccurately within the medico-legal literature. Such events involve comprehensively PO fatalities and allow for subtle separation of natural and unnatural death, at least from the prospective of forensic pathology. Iatrogenic deaths in this field can be separated into some major categories, as attributable to previous patient’s unfavorable conditions or depending from surgical procedure per se (such as PO cardiac and cerebrovascular events). In this review, the authors carried out syntheses of specific research areas regarding epidemiology, complications of general and spinal anesthetic, failure in airway management and patient’s circulatory homeostasis, and adverse drugs reactions; analysis considering the challenge of anesthetic-related mortality, epidemiology and classifications, by indicating causal chain of death, in respect of both contributing and associated anesthetic and surgery facts. Conclusions: Perioperative quality control programs and its relevance for medico-legal evaluation are emphasized as, although mortality rates have decreased worldwide over the last decades, however, preventable drug-related deaths still happen. Such fatal events have to be considered within the field of forensic pathology experts, with regard of malpractice claims, to implement a strategy for preventing potentially fatal complications

A minimum-disturbing quantum state discriminator

We propose two experimental schemes for quantum state discrimination that achieve the optimal tradeoff between the probability of correct identification and the disturbance on the quantum state.Comment: 9 pages, 1 figure, OSID style. Submitted to the special issue of "Open Systems and Information Dynamics", Proceedings of the "38th Symposium on Mathematical Physics", Torun, Poland, June 200

Linear entropy as an entanglement measure in two-fermion systems

We describe an efficient theoretical criterion, suitable for indistinguishable particles to quantify the quantum correlations of any pure two-fermion state, based on the Slater rank concept. It represents the natural generalization of the linear entropy used to treat quantum entanglement in systems of non-identical particles. Such a criterion is here applied to an electron-electron scattering in a two-dimensional system in order to perform a quantitative evaluation of the entanglement dynamics for various spin configurations and to compare the linear entropy with alternative approaches. Our numerical results show the dependence of the entanglement evolution upon the initial state of the system and its spin components. The differences with previous analyses accomplished by using the von Neumann entropy are discussed. The evaluation of the entanglement dynamics in terms of the linear entropy results to be much less demanding from the computational point of view, not requiring the diagonalization of the density matrix.Comment: 16 pages. Added references in section 1 Corrected typo

Entanglement dynamics of electron-electron scattering in low-dimensional semiconductor systems

We perform the quantitative evaluation of the entanglement dynamics in scattering events between two insistinguishable electrons interacting via Coulomb potential in 1D and 2D semiconductor nanostructures. We apply a criterion based on the von Neumann entropy and the Schmidt decomposition of the global state vector suitable for systems of identical particles. From the timedependent numerical solution of the two-particle wavefunction of the scattering carriers we compute their entanglement evolution for different spin configurations: two electrons with the same spin, with different spin, singlet, and triplet spin state. The procedure allows to evaluate the mechanisms that govern entanglement creation and their connection with the characteristic physical parameters and initial conditions of the system. The cases in which the evolution of entanglement is similar to the one obtained for distinguishable particles are discussed.Comment: 22 pages, 7 figures, submitted to Physical Review