Search results for "QB"

Coronal Loops: Observations and Modeling of Confined Plasma

2010

Coronal loops are the building blocks of the X-ray bright solar corona. They owe their brightness to the dense confined plasma, and this review focuses on loops mostly as structures confining plasma. After a brief historical overview, the review is divided into two separate but not independent sections: the first illustrates the observational framework, the second reviews the theoretical knowledge. Quiescent loops and their confined plasma are considered, and therefore topics such as loop oscillations and flaring loops (except for non-solar ones which provide information on stellar loops) are not specifically addressed here. The observational section discusses loop classification and popula…

Entanglement robustness via spatial deformation of identical particle wave functions

2021

We address the problem of entanglement protection against surrounding noise by a procedure suitably exploiting spatial indistinguishability of identical subsystems. To this purpose, we take two initially separated and entangled identical qubits interacting with two independent noisy environments. Three typical models of environments are considered: amplitude damping channel, phase damping channel and depolarizing channel. After the interaction, we deform the wave functions of the two qubits to make them spatially overlap before performing spatially localized operations and classical communication (sLOCC) and eventually computing the entanglement of the resulting state. This way, we show tha…

Quantum Probes for the Characterization of Nonlinear Media

2021

Active optical media leading to interaction Hamiltonians of the form H=λ˜(a+a†)ζ represent a crucial resource for quantum optical technology. In this paper, we address the characterization of those nonlinear media using quantum probes, as opposed to semiclassical ones. In particular, we investigate how squeezed probes may improve individual and joint estimation of the nonlinear coupling λ˜ and of the nonlinearity order ζ. Upon using tools from quantum estimation, we show that: (i) the two parameters are compatible, i.e., the may be jointly estimated without additional quantum noise

The Rail Quality Index as an Indicator of the “Global Comfort” in Optimizing Safety, Quality and Efficiency in Railway Rails

2012

AbstractThe proposed model uses the stochastic dynamic programming and in particular Markov decision processes applied to the Rail Quality Index (RQI - Italian Indice di Qualità del Binario, IQB).By performing the integrated analysis of the classes of variables which characterize the overall service quality (in terms of comfort and safety), the proposed mathematical approach allows to find the solutions to the decision-making process in function of the probability of deterioration of the state variables of the infrastructure over time and of the flow of available resources.

Two-qubit entanglement generation through non-Hermitian Hamiltonians induced by repeated measurements on an ancilla

2020

In contrast to classical systems, actual implementation of non-Hermitian Hamiltonian dynamics for quantum systems is a challenge because the processes of energy gain and dissipation are based on the underlying Hermitian system&ndash

Multi-State Quantum Dissipative Dynamics in Sub-Ohmic Environment: The Strong Coupling Regime

2015

We study the dissipative quantum dynamics and the asymptotic behavior of a particle in a bistable potential interacting with a sub-Ohmic broadband environment. The reduced dynamics, in the intermediate to strong dissipation regime, is obtained beyond the two-level system approximation by using a real-time path integral approach. We find a crossover dynamic regime with damped intra-well oscillations and incoherent tunneling and a completely incoherent regime at strong damping. Moreover, a nonmonotonic behavior of the left/right well population difference is found as a function of the damping strength.

Robust and Model Predictive Control applied to DC/DC converters and Shunt Active Filters

Al giorno d'oggi, la domanda di energia elettrica incrementa giorno per giorno. La gente spesso la usa con superficialità sottovalutando quanto essa sia preziosa. Fino a qualche decennio fa, la generazione di energia elettrica era centralizzata e dipendeva dallo sfruttamento delle risorse fossili. La limitatezza delle fonti fossili, insieme agli effetti ambientali del loro sfruttamento, hanno portato la ricerca a trovare vettori energetici alternativi poco inquinanti e facilmente reperibili. Lo sviluppo e la diffusione delle fonti energetiche rinnovabili hanno sancito la fine di una rete elettrica centralizzata a favore di una nuova idea di rete elettrica di tipo distribuita che permette di…

A prospective new diagnostic technique for distinguishing eruptive and noneruptive active regions

2019

This research has received funding from the Science and Technology Facilities Council (UK) through the consolidated grant ST/N000609/1 and the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program (grant agreement No. 647214). This work used the DiRAC@Durham facility managed by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). The equipment was funded by BEIS capital funding via STFC capital grants ST/P002293/1, ST/R002371/1, and ST/S002502/1, Durham University and STFC operations grant ST/R000832/1. DiRAC is part of the National e-Infrastructure. S.L.Y. would like to acknowledge STFC for sup…

Reduction of stored-particle background by a magnetic pulse method at the KATRIN experiment

2018

Arenz, M., et al. “Reduction of Stored-Particle Background by a Magnetic Pulse Method at the KATRIN Experiment.” The European Physical Journal C, vol. 78, no. 9, Sept. 2018. © 2018 The Authors

Suppression of Penning discharges between the KATRIN spectrometers

2020

The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to determine the effective electron (anti)neutrino mass with a sensitivity of $0.2\textrm{ eV/c}^2$ (90$\%$ C.L.) by precisely measuring the endpoint region of the tritium $\beta$-decay spectrum. It uses a tandem of electrostatic spectrometers working as MAC-E (magnetic adiabatic collimation combined with an electrostatic) filters. In the space between the pre-spectrometer and the main spectrometer, an unavoidable Penning trap is created when the superconducting magnet between the two spectrometers, biased at their respective nominal potentials, is energized. The electrons accumulated in this trap can lead to discharges, which create a…