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

Oscillations of the purity in the repeated-measurement-based generation of quantum states

Repeated observations of a quantum system interacting with another one can drive the latter toward a particular quantum state, irrespectively of its initial condition, because of an {\em effective non-unitary evolution}. If the target state is a pure one, the degree of purity of the system approaches unity, even when the initial condition of the system is a mixed state. In this paper we study the behavior of the purity from the initial value to the final one, that is unity. Depending on the parameters, after a finite number of measurements, the purity exhibits oscillations, that brings about a lower purity than that of the initial state, which is a point to be taken care of in concrete applications.Comment: 5 pages, 3 figure

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

Smart technologies: useful tools to assess the exposure to solar ultraviolet radiation for general population and outdoor workers

Beside some documented benefits attributed to ultraviolet solar radiation (solar UVR), a lot of adverse effects are a consequence of a chronic exposure, including the occurrence of photo-induced skin cancer. Improvement in risks perception, due to UVR overexposure, in the case of occupational or recreational exposure, is of great importance for public health. The amount of exposure to UVR has to be assessed as accurately as possible, with the aim to characterize different exposure conditions and, by their appropriate management, to prevent adverse health effects attributed to prolonged exposure to solar radiation (SR). The available technology allows to acquire such information, either using miniaturized and wearable sensors, or through devices who exploit radiative transfer models by integrating satellite-based radiometric data with meteorological data. We proceeded to an intercomparison to evaluate the performance of different devices in three commonly exposure conditions. Applications using satellite data, developed for preventing sunburn during recreational exposure, are adeguate for that purpose, while for a more accurate exposure assessment, only those which evaluate the irradiance in near real-time provide acceptable results. Unlike earlier, the low-cost devices that use wearable sensors showed inadequate performance for our purpose

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

Propagation of Artemisia arborescens L. by stem-cutting: adventitious root formation under different conditions

Artemisia arborescens L. has gained a strong importance worldwide due to its many industrial uses and it has been recently considered as ornamental plant. A major constraint to its widespread cultivation is represented, by far, by the scarce availability of high-quality plant material for field establishment; hence, development of a fast and effective methods for its vegetative propagation is needed. An experiment was conducted to assess the effects of different harvest periods, NAA, and rooting substrates on rooting of stem cuttings of A. arborescens. Semi hardwood cuttings were collected from wild plants in February, April, and November. Half of the material was treated with 0.4% NAA and placed on different mixtures of sphagnum peat and perlite (2 : 1, 1 : 1, and 1 : 2 v/v) under mist. After 40 days the percentage of rooted cuttings was significantly influenced by the harvest period as cuttings collected in February showed the highest rooting rate, and numerous alive but not rooted cuttings evidenced callus formation. In contrast, the use of different rooting substrates as well as NAA addition did not show any significant effect on rooting capacity. The best results, in terms of root number (4.2) and root length (8.8 cm), were achieved on cuttings grown in a 1 : 1 v/v sphagnum peat : perlite mixture, without NAA application

Effect of current corrugations on the stability of the tearing mode

The generation of zonal magnetic fields in laboratory fusion plasmas is predicted by theoretical and numerical models and was recently observed experimentally. It is shown that the modification of the current density gradient associated with such corrugations can significantly affect the stability of the tearing mode. A simple scaling law is derived that predicts the impact of small stationary current corrugations on the stability parameter $\Delta'$. The described destabilization mechanism can provide an explanation for the trigger of the Neoclassical Tearing Mode (NTM) in plasmas without significant MHD activity.Comment: Accepted to Physics of Plasma

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

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.