Geometric phase accumulation-based effects in the quantum dynamics of an anisotropically trapped ion

New physical effects in the dynamics of an ion confined in an anisotropic two-dimensional Paul trap are reported. The link between the occurrence of such manifestations and the accumulation of geometric phase stemming from the intrinsic or controlled lack of symmetry in the trap is brought to light. The possibility of observing in laboratory these anisotropy-based phenomena is briefly discussed.Comment: 10 pages. Acta Physica Hungarica B 200

Zeno Dynamics and High-Temperature Master Equations Beyond Secular Approximation

Complete positivity of a class of maps generated by master equations derived beyond the secular approximation is discussed. The connection between such class of evolutions and physical properties of the system is analyzed in depth. It is also shown that under suitable hypotheses a Zeno dynamics can be induced because of the high temperature of the bath.Comment: 9 pages, 2 figure

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

Quantum Zeno Subspaces induced by Temperature

We discuss the partitioning of the Hilbert space of a quantum system induced by the interaction with another system at thermal equilibrium, showing that the higher the temperature the more effective is the formation of Zeno subspaces. We show that our analysis keeps its validity even in the case of interaction with a bosonic reservoir, provided appropriate limitations of the relevant bandwidth.Comment: 9 pages, 3 figure

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

GEOMETRY AND INFORMATION FOR THE PRESERVATION OF A ROMAN MOSAIC THROUGH A HBIM APPROACH

Abstract. The archaeological site is a mine of data and information that helps to deepen the knowledge of its origin, history, and structure. This virtuous approach becomes even more effective when these data, properly processed and structured, form the basis for a project of conservation and enhancement of the cultural asset.The Roman mosaics dug in Castiglione delle Stiviere in 1995 represent an interesting case in which all the archaeological information, made available by the Superintendence, was used through an HBIM (Historical Building Information Modeling) approach for the conservation project. The Stratigraphic Units (US) of the findings have identified the strategy for the geometric and informative modeling of the BIM (Building Information Modeling) model and have also been exploited in the design phase for the project of the new roof structure and especially for the cost analysis. The structuring of the data by stratigraphic units was also used in the drafting of the preventive and planned conservation, necessary to enhance and prolong the state of good health of the property.This work has been developed in the internship activity within a training course on HBIM, in collaboration with the Diocese of Mantua, owner of the property

Brownian Dynamics Simulation of Polydisperse Hard Spheres

Standard algorithms for the numerical integration of the Langevin equation require that interactions are slowly varying during to the integration timestep. This in not the case for hard-body systems, where there is no clearcut between the correlation time of the noise and the timescale of the interactions. Starting from a short time approximation of the Smoluchowsky equation, we introduce an algorithm for the simulation of the overdamped Brownian dynamics of polydisperse hard-spheres in absence of hydrodynamics interactions and briefly discuss the extension to the case of external drifts

Population trapping due to cavity losses

In population trapping the occupation of a decaying quantum level keeps a constant non-zero value. We show that an atom-cavity system interacting with an environment characterized by a non-flat spectrum, in the non-Markovian limit, exhibits such a behavior, effectively realizing the preservation of nonclassical states against dissipation. Our results allow to understand the role of cavity losses in hybrid solid state systems and pave the way to the proper description of leakage in the recently developed cavity quantum electrodynamic systems.Comment: 4 pages, 3 figures, version accepted for publication on Phys. Rev.

Evaluation of configurational entropy of a model liquid from computer simulations

Computer simulations have been employed in recent years to evaluate the configurational entropy changes in model glass-forming liquids. We consider two methods, both of which involve the calculation of the `intra-basin' entropy as a means for obtaining the configurational entropy. The first method involves the evaluation of the intra-basin entropy from the vibrational frequencies of inherent structures, by making a harmonic approximation of the local potential energy topography. The second method employs simulations that confine the liquid within a localized region of configuration space by the imposition of constraints; apart from the choice of the constraints, no further assumptions are made. We compare the configurational entropies estimated for a model liquid (binary mixture of particles interacting {\it via} the Lennard-Jones potential) for a range of temperatures, at fixed density.Comment: 10 pages, 5 figures, Proceedings of "Unifying Concepts in Glass Physics" Trieste 1999 (to appear in J. Phys. Cond. Mat.

Does positive reinforcement training affect the behaviour and welfare of zoo animals? The case of the ring-tailed lemur (Lemur catta)

Positive reinforcement training (PRT) is an established tool to facilitate animal husbandry, care and research in modern zoos, with potential positive implications for captive animal welfare. The study explored the role of an isolation PRT training programme on the well-being of ring-tailed lemurs (Lemur catta). Eleven subjects were observed during an isolation training protocol to induce the animals to enter an area (training area) calmly and retrieve rewards separated from group members. Duration of individual and social behaviours were collected over two different periods: the baseline period, before the beginning of the isolation training protocol and the training period, in which the collection of the data started at the end of the isolation training sessions. Additionally, behavioural data within the isolation training sessions (latency to enter the training area and retrieve the reward, display of stress-related behaviours) were recorded. Outside the training sessions, lemurs were out of sight significantly more in the baseline (Mean ± SD: 15.46 ± 5.20) than in the training (Mean ± SD: 4.36 ± 2.89) period. Social behaviour was performed significantly more in the training (Mean ± SD: 31.80 ± 12.34) than in the baseline (Mean ± SD: 12.52 ± 5.14) period; particularly, lemurs were in social contact significantly more in the training (Mean ± SD: 14.09 ± 6.00) than in the baseline period (Mean ± SD: 4.58 ± 2.73). Agonistic behaviours were performed significantly more in the baseline (Mean ± SD: 0.23 ± 0.15) than in the training (Mean ± SD: 0.07 ± 0.07) period. Within the training sessions, all the individuals entered the training area, were isolated from conspecifics, and retrieved the reward in 6 out of 9 sessions. Our findings show that, during the PRT period, lemurs displayed their natural behaviour in their everyday social life with significant increase of their affiliative behaviours and decrease of aggressive behaviours with benefits for their welfare status. Thus, lemurs were able to cope with the use of PRT to isolate each individual from its social group – a situation which, without training, might be very stressful. In conclusion, PRT may play a crucial role for the captive management of ring-tailed lemurs in captive facilities, including zoos