Continuous variable entanglement dynamics in structured reservoirs

We address the evolution of entanglement in bimodal continuous variable quantum systems interacting with two independent structured reservoirs. We derive an analytic expression for the entanglement of formation without performing the Markov and the secular approximations and study in details the entanglement dynamics for various types of structured reservoirs and for different reservoir temperatures, assuming the two modes initially excited in a twin-beam state. Our analytic solution allows us to identify three dynamical regimes characterized by different behaviors of the entanglement: the entanglement sudden death, the non-Markovian revival and the non-secular revival regimes. Remarkably, we find that, contrarily to the Markovian case, the short-time system-reservoir correlations in some cases destroy quickly the initial entanglement even at zero temperature.Comment: 12 pages, 8 figure

Thermodynamic fingerprints of non-Markovianity in a system of coupled superconducting qubits

The exploitation and characterization of memory effects arising from the interaction between system and environment is a key prerequisite for quantum reservoir engineering beyond the standard Markovian limit. In this paper we investigate a prototype of non-Markovian dynamics experimentally implementable with superconducting qubits. We rigorously quantify non-Markovianity highlighting the effects of the environmental temperature on the Markovian to non-Markovian crossover. We investigate how memory effects influence, and specifically suppress, the ability to perform work on the driven qubit. We show that the average work performed on the qubit can be used as a diagnostic tool to detect the presence or absence of memory effects.Comment: 9 page

Tracking sand-fairways through a deformed turbidite system : the Numidian (Miocene) of Central Sicily, Italy

The research presented here is funded by BG Group in partnership with CNPq-Brazil (National Council for Scientific and Technological Development). Rosanna Maniscalco acknowledges a FIR 2014 grant awarded from the University of Catania. We thank Christian Haug Eide, David Hodgson and Enrico Tavarnelli for constructive and thorough reviews on an earlier draft that have greatly improved this contribution.Peer reviewedPublisher PD

Decoherence and robustness of parity-dependent entanglement in the dynamics of a trapped ion

We study the entanglement between the 2D vibrational motion and two ground state hyperfine levels of a trapped ion, Under particular conditions this entanglement depends on the parity of the total initial vibrational quanta. We study the robustness of this quantum coherence effect with respect to the presence of non-dissipative sources of decoherence, and of an imperfect initial state preparation.Comment: 13 pages, 5 figure

Syn-kinematic sedimentary systems as constraints on the structural response of thrust belts : re-examining the structural style of the Maghrebian thrust belt of Eastern Sicily

We are indebted to the generosity of the late Fabio Lentini. While he may not have agreed with our findings, he nevertheless openly and cheerfully shared his mapping and insight of Sicilian geology. This work also builds upon many years’ collaboration between us, initiated by the late Mario Grasso (the Pantagruelian Master of Speranza et alii, 2018). The mapping of Lentini, Grasso and colleagues represents a remarkable resource for future geologists. We dedicate this contribution to their memory. We thank Sveva Corrado and an anonymous referee for constructive comments on an earlier draft of this paper. Butler’s Sicilian field research has been variously funded by the UK’s Natural Environment Research Council and the Royal Society. Maniscalco acknowledges “Fondi per la Ricerca di AteneoPiano per la Ricerca 2016/2018”. Pinter was supported through a PhD grant funded by the BG Group (now Shell) and Brazil’s National Council for Scientific and Technological Development (CNPq).Peer reviewedPublisher PD

Continuous Monitoring of Dynamical Systems and Master Equations

We illustrate the equivalence between the non-unitary evolution of an open quantum system governed by a Markovian master equation and a process of continuous measurements involving this system. We investigate a system of two coupled modes, only one of them interacting with external degrees of freedom, represented, in the first case, by a finite number of harmonic oscillators, and, in the second, by a sequence of atoms where each one interacts with a single mode during a limited time. Two distinct regimes appear, one of them corresponding to a Zeno-like behavior in the limit of large dissipation

Tripartite entanglement dynamics in a system of strongly driven qubits

We study the dynamics of tripartite entanglement in a system of two strongly driven qubits individually coupled to a dissipative cavity. We aim at explanation of the previously noted entanglement revival between two qubits in this system. We show that the periods of entanglement loss correspond to the strong tripartite entanglement between the qubits and the cavity and the recovery has to do with an inverse process. We demonstrate that the overall process of qubit-qubit entanglement loss is due to the second order coupling to the external continuum which explains the exp[-g^2 t/2+g^2 k t^3/6+\cdot] for of the entanglement loss reported previously.Comment: 9 pages, 5 figure

Limits in the characteristic function description of non-Lindblad-type open quantum systems

In this paper I investigate the usability of the characteristic functions for the description of the dynamics of open quantum systems focussing on non-Lindblad-type master equations. I consider, as an example, a non-Markovian generalized master equation containing a memory kernel which may lead to nonphysical time evolutions characterized by negative values of the density matrix diagonal elements [S.M. Barnett and S. Stenholm, Phys. Rev. A {\bf 64}, 033808 (2001)]. The main result of the paper is to demonstrate that there exist situations in which the symmetrically ordered characteristic function is perfectly well defined while the corresponding density matrix loses positivity. Therefore nonphysical situations may not show up in the characteristic function. As a consequence, the characteristic function cannot be considered an {\it alternative complete} description of the non-Lindblad dynamics.Comment: Revised version. 4 pages, 1 figur

Microscopic derivation of the Jaynes-Cummings model with cavity losses

In this paper we provide a microscopic derivation of the master equation for the Jaynes-Cummings model with cavity losses. We single out both the differences with the phenomenological master equation used in the literature and the approximations under which the phenomenological model correctly describes the dynamics of the atom-cavity system. Some examples wherein the phenomenological and the microscopic master equations give rise to different predictions are discussed in detail.Comment: 9 pages, 3 figures New version with minor correction Accepted for publication on Physical Review