Charger-mediated energy transfer in exactly-solvable models for quantum batteries

We present a systematic analysis and classification of several models of quantum batteries involving different combinations of two level systems and quantum harmonic oscillators. In particular, we study energy transfer processes from a given quantum system, termed charger, to another one, i.e. the proper battery. In this setting, we analyze different figures of merit, including the charging time, the maximum energy transfer, and the average charging power. The role of coupling Hamiltonians which do not preserve the number of local excitations in the charger-battery system is clarified by properly accounting them in the global energy balance of the model.Comment: 11 page

Charger-mediated energy transfer for quantum batteries: an open system approach

The energy charging of a quantum battery is analyzed in an open quantum setting, where the interaction between the battery element and the external power source is mediated by an ancilla system (the quantum charger) that acts as a controllable switch. Different implementations are analyzed putting emphasis on the interplay between coherent energy pumping mechanisms and thermalization

Quantum bath statistics tagging

The possibility of discriminating the statistics of a thermal bath using indirect measurements performed on quantum probes is presented. The scheme relies on the fact that, when weakly coupled with the environment of interest, the transient evolution of the probe toward its final thermal configuration, is strongly affected by the fermionic or bosonic nature of the bath excitations. Using figures of merit taken from quantum metrology such as the Holevo-Helstrom probability of error and the Quantum Chernoff bound, we discuss how to achieve the greatest precision in this statistics tagging procedure, analyzing different models of probes and different initial preparations and by optimizing over the time of exposure of the probe

Recovering complete positivity of non-Markovian quantum dynamics with Choi-proximity regularization

A relevant problem in the theory of open quantum systems is the lack of complete positivity of dynamical maps obtained after weak-coupling approximations, a famous example being the Redfield master equation. A number of approaches exist to recover well-defined evolutions under additional Markovian assumptions, but much less is known beyond this regime. Here we propose a numerical method to cure the complete-positivity violation issue while preserving the non-Markovian features of an arbitrary original dynamical map. The idea is to replace its unphysical Choi operator with its closest physical one, mimicking recent work on quantum process tomography. We also show that the regularized dynamics is more accurate in terms of reproducing the exact dynamics: this allows to heuristically push the utilization of these master equations in moderate coupling regimes, where the loss of positivity can have relevant impact.Comment: 12 pages, 5 figure

Going beyond Local and Global approaches for localized thermal dissipation

Identifying which master equation is preferable for the description of a multipartite open quantum system is not trivial and has led in the recent years to the local vs. global debate in the context of Markovian dissipation. We treat here a paradigmatic scenario in which the system is composed of two interacting harmonic oscillators A and B, with only A interacting with a thermal bath - collection of other harmonic oscillators - and we study the equilibration process of the system initially in the ground state with the bath finite temperature. We show that the completely positive version of the Redfield equation obtained using coarse-grain and an appropriate time-dependent convex mixture of the local and global solutions give rise to the most accurate semigroup approximations of the whole exact system dynamics, i.e. both at short and at long time scales, outperforming the local and global approaches

Patterns of CT lung injury and toxicity after stereotactic radiotherapy delivered with helical tomotherapy in early stage medically inoperable NSCLC

To evaluate toxicity and patterns of radiologic lung injury on CT images after hypofractionated image-guided stereotactic body radiotherapy (SBRT) delivered with helical tomotherapy (HT) in medically early stage inoperable non-small-cell lung cancer (NSCLC)

Introducing Collaboration in Single-user Applications through the Centralized Control Architecture

In this paper we describe a novel Model-View­ Controller based architecture, Centralized Control, that intro­duces collaboration in single-users applications. The architecture is able to add collaboration with no need to modify the source code of the original single-user application, and providing also the capability to introduce group semantics into the new, collab­orative application that is obtained. The architecture is shown in practice, by introducing CollabXMind, a collaborative mind map tool, that is based on a well-known single-user tool, XMind

Discrimination of thermal baths by single qubit probes

Non-equilibrium states of quantum systems in contact with thermal baths help telling environments with different temperatures or different statistics apart. We extend these studies to a more generic problem that consists in discriminating between two baths with disparate constituents at unequal temperatures. Notably there exist temperature regimes in which the presence of coherence in the initial state preparation is beneficial for the discrimination capability. We also find that non-equilibrium states are not universally optimal, and detail the conditions in which it becomes convenient to wait for complete thermalisation of the probe. These concepts are illustrated in a linear optical simulation.Comment: Few typos corrected, bibliography expande

Productivity and quality of different tomato cultivars under intercropping system with maize and dry farming conditions in Southern Italy

This research, carried out in a typical Mediterranean environment of Southern Italy, reports some quantitative and qualitative traits of three local tomato cultivars (‘Arsicolo’, ‘Crovarese’, and ‘San Marzano’) plus a commercial one (‘Datterino’) cultivated without irrigation and intercropped with maize. For each cultivar, in addition to the determination of fruit production, tomato paste and “conserva” paste were prepared using a traditional technique of the Tanagro Valley (province of Salerno, Southern Italy). Results highlighted that ‘Arsicolo’ showed the best fruit yield (32.2 metric tons ha-1) and tomato paste production (92.9% paste return by tomato fruits weight) due to its ancient peculiar adaptability to cultivation in dry conditions, while ‘Datterino’, ‘Crovarese’, and ‘San Marzano’ had 19, 16.7, 10.5 tons ha-1 of fruit yield and 85.7, 83.9, 76.2% of tomato paste return, respectively. Conversely, for the qualitative traits, such as total solids, soluble solids, titratable acidity, and ascorbic acid, ‘Crovarese’ showed the best results (9.1%, 6.6 °Brix, 0.93%, and 39.7 mg per 100 g of fresh weight, respectively). The two components extracted by the principal components analysis (PCA) explained 84.9% of the total variance in the morphological, quantitative and qualitative traits and the dendrogram obtained by hierarchical cluster analysis allowed to divide the cultivars into three groups. Our findings highlighted that local tomato cultivars, intercropped with maize, can be cultivated adopting only few sustainable field operations and with no irrigation