Forgetfulness of continuous Markovian quantum channels

The notion of forgetfulness, used in discrete quantum memory channels, is slightly weakened in order to be applied to the case of continuous channels. This is done in the context of quantum memory channels with Markovian noise. As a case study, we apply the notion of weak-forgetfulness to a bosonic memory channel with additive noise. A suitable encoding and decoding unitary transformation allows us to unravel the effects of the memory, hence the channel capacities can be computed using known results from the memoryless setting.Comment: 6 pages, 2 figures, comments are welcome. Minor corrections and acknoledgment adde

Implementation of Non-Reflecting Boundary Conditions in a Finite Volume Unstructured Solver for the Study of Turbine Cascades

The analysis of component interaction in the turbomachinery field is nowadays of growing importance. This leads to the combination of different approaches, such as Large Eddy Simulation for combustors and Unsteady Reynolds-Averaged Navier-Stokes equations for turbines, and is responsible for the increase of both computational effort and required accuracy of the numerical tools. To guarantee accurate results and efficient convergence rates, numerical schemes must handle the spurious reflecting waves coming from the boundaries of truncated domains. This can be achieved by means of Non-Reflecting Boundary Conditions. The research activity described in the present paper is aimed at implementing the method of Non-Reflecting Boundary Conditions for the Linearized Euler Equations proposed by Giles in an in-house finite volume implicit time-marching solver. The methodology is validated using the available experimental data obtained at the von Karman Institute for Fluid Dynamics on the LS89 High-Pressure Turbine vane for both subsonic and transonic working condition. The implemented approach demonstrates its importance for the correct evaluation of the pressure distribution both on the vane surface and in the pitchwise direction when the computational domain is truncated at the experimental probe's position

Topology and quantum states: The electron-monopole system

This paper starts by describing the dynamics of the electronmonopole system at both classical and quantum level by a suitable reduction procedure. This suggests, in order to realise the space of states for quantum systems which are classically described on topologically non-trivial configuration spaces, to consider Hilbert spaces of exterior differential forms. Among the advantages of this formulation, we present—in the case of the group SU(2), how it is possible to obtain all unitary irreducible representations on such a Hilbert space, and how it is possible to write scalar Dirac-type operators, following an idea by K¨ahler

Memory effects in attenuation and amplification quantum processes

With increasing communication rates via quantum channels, memory effects become unavoidable whenever the use rate of the channel is comparable to the typical relaxation time of the channel environment. We introduce a model of a bosonic memory channel, describing correlated noise effects in quantum-optical processes via attenuating or amplifying media. To study such a channel model, we make use of a proper set of collective field variables, which allows us to unravel the memory effects, mapping the n-fold concatenation of the memory channel to a unitarily equivalent, direct product of n single-mode bosonic channels. We hence estimate the channel capacities by relying on known results for the memoryless setting. Our findings show that the model is characterized by two different regimes, in which the cross correlations induced by the noise among different channel uses are either exponentially enhanced or exponentially reduced.Comment: 10 pages, 7 figures, close to the published versio

Molecular Beams

Contains reports on five research projects.Lincoln Laboratory (Purchase Order DDL B-00306)United States Air Force (Contract AF19(604)-7400)United States NavyUnited States Arm

The Expander-Implant Breast Reconstruction in the COVID Era: Which is the “Unhappy” Tissue Expander Priority?

Breast surgeons seem to agree on the fact that a same-day surgery (mastectomy and breast reconstruction) protocol provides appropriate cancer treatment during times of unprecedented resource limitations, such as in the COVID era. In this scenario, pre-pectoral implant-based breast reconstruction can be definitively considered a sustainable technique. Nevertheless, the authors focus on the management of patients who had already undergone a same day procedure with two-stage breast reconstruction, implanting a breast tissue expander during the last two-year period and have been progressively delayed according to a surgical care based on priority. We coined the expression “unhappy tissue expander” to define all those symptomatic patients for which surgery should not be delayed even during an epidemic context. Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266

Architecture of collaborating frameworks: simulation, visualisation, user interface and analysis

The Anaphe project is an ongoing effort to provide an Object Oriented software environment for data analysis in HENP experiments. A range of commercial and public domain libraries is used to cover basic functionalities; on top of these libraries a set of HENP-specific C++ class libraries for histogram management, fitting, plotting and ntuple-like data analysis has been developed. In order to comply with the user requirements for a command-line driven tool, we have chosen to use a scripting language (Python) as the front-end for a data analysis tool. The loose coupling provided by the consequent use of (AIDA compliant) Abstract Interfaces for each component in combination with the use of shared libraries for their implementation provides an easy integration of existing libraries into modern scripting languages thus allowing for rapid application development. This integration is simplified even further using a specialised toolkit (SWIG) to create "shadow classes" for the Python language, which map the definitions of the Abstract Interfaces almost at a one-to-one level. This paper will give an overview of the architecture and design choices and will present the current status and future developments of the project

Robustness against parametric noise of non ideal holonomic gates

Holonomic gates for quantum computation are commonly considered to be robust against certain kinds of parametric noise, the very motivation of this robustness being the geometric character of the transformation achieved in the adiabatic limit. On the other hand, the effects of decoherence are expected to become more and more relevant when the adiabatic limit is approached. Starting from the system described by Florio et al. [Phys. Rev. A 73, 022327 (2006)], here we discuss the behavior of non ideal holonomic gates at finite operational time, i.e., far before the adiabatic limit is reached. We have considered several models of parametric noise and studied the robustness of finite time gates. The obtained results suggest that the finite time gates present some effects of cancellation of the perturbations introduced by the noise which mimic the geometrical cancellation effect of standard holonomic gates. Nevertheless, a careful analysis of the results leads to the conclusion that these effects are related to a dynamical instead of geometrical feature.Comment: 8 pages, 8 figures, several changes made, accepted for publication on Phys. Rev.