Dynamics of a two-state system through a real level crossing

The dynamics of a two-state system whose energies undergo a real crossing at some instant of time is studied. At this instant, both the coupling and the detuning vanish simultaneously, which leads to an exact degeneracy of the eigenenergies of the system. It is found that the dynamics of the system is primarily determined by the manner in which the degeneracy occurs. This interesting behavior is reminiscent of a symmetry breaking process, since the totally symmetric situation occurring at the crossing is significantly altered by infinitesimal quantities, which remove the degeneracy, with very important dynamical implications from there on. A very simple analytical formula is derived, which is found to describe the population changes very accurately

Diritto penale del rischio e rischi del diritto penale tra scienza e societ\ue0

Il contributo esamina i caratteri del modello di diritto penale caratterizzato dal riferimento al rischio, evidenziando i diversi ruoli dogmatici che tale nozione ha assunto e testando la sua utilit\ue0 alla luce delle situazioni caratterizzate da incertezza scientifica, con particolare riferimento alla vicenda processuale in primo grado del terremoto dell'Aquila

La pertenencia a una organización criminal como tipo penal modelo europeo

Il lavoro diffonde nel circuito penalistico di lingua spagnolo i risultati in tema di punibilità della partecipazione ad una organizzazione criminale come modello europeo di incriminazione. Partendo dal rilievo criminologico della dimensione transnazionale assunta in modo crescente dalle organizzazioni criminali, si analizza la diversità di risposte incriminatrici nei sistemi penali degli stati mebri dell'UE, individuando tre principali tipologie di risposte nazionali. Per armonizzare tale differenti posizioni all'interno dello spazio comune europeo di giustizia sicurezza e libertà, il contributo prospetta e motiva una proposta di modello di incriminazione in materia di gruppi criminali

Microscopic description of dissipative dynamics of a level crossing transition

We analyze the effect of a dissipative bosonic environment on the Landau-Zener-Stuckelberg-Majorana (LZSM) level crossing model by using a microscopic approach to derive the relevant master equation. For an environment at zero temperature and weak dissipation our microscopic approach confirms the independence of the survival probability on the decay rate that has been predicted earlier by the simple phenomenological LZSM model. For strong decay the microscopic approach predicts a notable increase of the survival probability, which signals dynamical decoupling of the initial state. Unlike the phenomenological model our approach makes it possible to study the dependence of the system dynamics on the temperature of the environment. In the limit of very high temperature we find that the dynamics is characterized by a very strong dynamical decoupling of the initial state - temperature-induced quantum Zeno effect.Comment: 6 pages, 4 figure

Speeding up antidynamical Casimir effect with nonstationary qutrits

The antidynamical Casimir effect (ADCE) is a term coined to designate the coherent annihilation of excitations due to resonant external perturbation of system parameters, allowing for extraction of quantum work from nonvacuum states of some field. Originally proposed for a two-level atom (qubit) coupled to a single cavity mode in the context of nonstationary quantum Rabi model, it suffered from very low transition rate and correspondingly narrow resonance linewidth. In this paper we show analytically and numerically that the ADCE rate can be increased by at least one order of magnitude by replacing the qubit by an artificial three-level atom (qutrit) in a properly chosen configuration. For the cavity thermal state we demonstrate that the dynamics of the average photon number and atomic excitation is completely different from the qubit's case, while the behavior of the total number of excitations is qualitatively similar yet significantly faster.Comment: 9 pages, 4 figure

Open multistate Majorana model

The Majorana model in the presence of dissipation and dephasing is considered. First, it is proven that increasing the Hilbert space dimension the system becomes more and more fragile to quantum noise, whether dephasing or dissipation are mainly present. Second, it is shown that, contrary to its ideal counterpart, the dynamics related to the open Majorana model cannot be considered as the combined dynamics of a set of independent spin-1/2 models

Stimulated Raman adiabatic passage in an open quantum system: Master equation approach

A master equation approach to the study of environmental effects in the adiabatic population transfer in three-state systems is presented. A systematic comparison with the non-Hermitian Hamiltonian approach [N. V. Vitanov and S. Stenholm, Phys. Rev. A {\bf 56}, 1463 (1997)] shows that in the weak coupling limit the two treatments lead to essentially the same results. Instead, in the strong damping limit the predictions are quite different: in particular the counterintuitive sequences in the STIRAP scheme turn out to be much more efficient than expected before. This point is explained in terms of quantum Zeno dynamics.Comment: 11 pages, 4 figure

A Multimodal Technique for an Embedded Fingerprint Recognizer in Mobile Payment Systems

The development and the diffusion of distributed systems, directly connected to recent communication technologies, move people towards the era of mobile and ubiquitous systems. Distributed systems make merchant-customer relationships closer and more flexible, using reliable e-commerce technologies. These systems and environments need many distributed access points, for the creation and management of secure identities and for the secure recognition of users. Traditionally, these access points can be made possible by a software system with a main central server. This work proposes the study and implementation of a multimodal technique, based on biometric information, for identity management and personal ubiquitous authentication. The multimodal technique uses both fingerprint micro features (minutiae) and fingerprint macro features (singularity points) for robust user authentication. To strengthen the security level of electronic payment systems, an embedded hardware prototype has been also created: acting as self-contained sensors, it performs the entire authentication process on the same device, so that all critical information (e.g. biometric data, account transactions and cryptographic keys), are managed and stored inside the sensor, without any data transmission. The sensor has been prototyped using the Celoxica RC203E board, achieving fast execution time, low working frequency, and good recognition performance