Degradation of Entanglement in Markovian Noise

The entanglement survival time is defined as the maximum time a system which is evolving under the action of local Markovian, homogenous in time noise, is capable to preserve the entanglement it had at the beginning of the temporal evolution. In this paper we study how this quantity is affected by the interplay between the coherent preserving and dissipative contributions of the corresponding dynamical generator. We report the presence of a counterintuitive, non-monotonic behaviour in such functional, capable of inducing sudden death of entanglement in models which, in the absence of unitary driving are capable to sustain entanglement for arbitrarily long times.Comment: 15 pages, 5 figure

Energy release as a parameter for fatigue design of additive manufactured metals

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Phase space Heisenberg-limited estimation of the average phase shift in a Mach–Zehnder interferometer

We address the problem of distributed quantum metrology with a single squeezed-vacuum source by using the formalism of quantum mechanics in phase space. In particular, we demonstrate Heisenberg-limited sensitivity in the measurement of the average of two arbitrary phase shifts in the arms of a Mach-Zehnder interferometer. We obtain exact results for the measurement probability at the interferometer output for any value of the phases, which give us insight into the emergence of Heisenberg-limited sensitivity for periodical values of the phases

Distributed quantum metrology with a single squeezed-vacuum source

We propose an interferometric scheme for the estimation of a linear combination with non-negative weights of an arbitrary number M > 1 of unknown phase delays, distributed across an M-channel linear optical network, with Heisenberg-limited sensitivity. This is achieved without the need of any sources of photon-number or entangled states, photon-number-resolving detectors, or auxiliary interferometric channels. Indeed, the proposed protocol remarkably relies upon a single squeezed-state source, an antisqueezing operation at the interferometer output, and on-off photodetectors

Preliminary design of next generation Mach 1.6 supersonic business jets to investigate landing & take-off (LTO) noise and emissions–SENECA

With the approach of next generation supersonic transport entry into service, new research activities were initiated to support updates on ICAO regulations and certification processes for supersonic transport vehicles. Within this context, the EU Horizon 2020 SENECA project has been launched to investigate the levels of noise and gaseous emissions in the vicinity of airports as well as the global climate impact of next generation supersonic civil aircraft. This paper introduces some of the preliminary outcomes of this investigation. It presents the preliminary design and performance analysis of a Mach 1.6 business jet, following an integrated aircraft-engine design approach. The preliminary design was performed accounting for the limitations posed by future environmental restrictions on respective subsonic vehicles. The market space and mission route definition exercise assumed only "over-sea" supersonic operations, while for "over-land", only subsonic operations where allowed. Parametric studies on engine integrated design demonstrated modest core temperatures while cruising and the significant impact of engine installation on performance. At this first design iteration, assuming current state of the art technology, the Mach 1.6 business jet showed good potential to satisfy the predicted mission requirements while respecting the environmental constraints in terms of Landing & Take-Off (LTO) noise and emissions

Chromosome evolution in Cophomantini (Amphibia, Anura, Hylinae)

The hylid tribe Cophomantini is a diverse clade of Neotropical treefrogs composed of the genera Aplastodiscus, Boana, Bokermannohyla, Hyloscirtus, and Myersiohyla. The phylogenetic relationships of Cophomantini have been comprehensively reviewed in the literature, providing a suitable framework for the study of chromosome evolution. Employing different banding techniques, we studied the chromosomes of 25 species of Boana and 3 of Hyloscirtus; thus providing, for the first time, data for Hyloscirtus and for 15 species of Boana. Most species showed karyotypes with 2n = 2x = 24 chromosomes; some species of the B. albopunctata group have 2n = 2x = 22, and H. alytolylax has 2n = 2x = 20. Karyotypes are all bi-armed in most species presented, with the exception of H. larinopygion (FN = 46) and H. alytolylax (FN = 38), with karyotypes that have a single pair of small telocentric chromosomes. In most species of Boana, NORs are observed in a single pair of chromosomes, mostly in the small chromosomes, although in some species of the B. albopunctata, B. pulchella, and B. semilineata groups, this marker occurs on the larger pairs 8, 1, and 7, respectively. In Hyloscirtus, NOR position differs in the three studied species: H. alytolylax (4p), H. palmeri (4q), and H. larinopygion (1p). Heterochromatin is a variable marker that could provide valuable evidence, but it would be necesserary to understand the molecular composition of the C-bands that are observed in different species in order to test its putative homology. In H. alytolylax, a centromeric DAPI+ band was observed on one homologue of chromosome pair 2. The band was present in males but absent in females, providing evidence for an XX/XY sex determining system in this species. We review and discuss the importance of the different chromosome markers (NOR position, C-bands, and DAPI/CMA3 patterns) for their impact on the taxonomy and karyotype evolution in Cophomantini

A multi-element psychosocial intervention for early psychosis (GET UP PIANO TRIAL) conducted in a catchment area of 10 million inhabitants: study protocol for a pragmatic cluster randomized controlled trial

Multi-element interventions for first-episode psychosis (FEP) are promising, but have mostly been conducted in non-epidemiologically representative samples, thereby raising the risk of underestimating the complexities involved in treating FEP in 'real-world' services

Degradation of Entanglement in Markovian Noise

In quantum information theory entanglement represents a fragile and volatile resource, responsible for both the unconventional power of quantum computers and the difficulty in building them. The aim of this thesis is understanding how the presence of noise in a quantum communication line degrades the entanglement content of a bipartite system during its transmission through it. Our attention is restricted to memory-less, time-omogenous noises, which are modeled by so-called quantum dynamical semigroups (QDS). A QDS is completely determined by its associated Lindbladian operator, or generator of the dynamics. Numerical methods and perturbation theory are used to determine the maximum transmission time associated to a given QDS as a function of the generator parameters. These parameters represent the relative weights of coherent and dissipative dynamics, and are generally under a good degree of control by the experimentalist. The first chapter of the thesis is devoted to reviewing the theory of the space of states, with a focus on entangled states and separability tests. In the second chapter the discussion continues with quantum channels, which provide the correct tool for describing a quantum communication line and the noise tampering it. The notion of QDS, which arise for instance in the weak-coupling limit and under the Born-Markov approximation, is also introduced in this chapter. The third chapter presents the class of entanglement-breaking channels, which represent the most detrimental form form of noise possible when considering the transmission of entanglement. The review ends with a short account of experimental tests of entanglement restoration protocols. In the fourth chapter the we study the entanglement transmission time, defined as the time instant at which entanglement is completely broken, as a mean of classifying noises with respect to their harmfulness to entanglement. Some study cases are then analyzed in detail. The examples chosen are relevant in the transmission of entangled photon pairs through an optical fiber, and match the experiments outlined at the end of the third chapter. The entanglement transmission time exhibits the same qualitative behaviour in the cases analyzed, dropping quickly as the QDS parameter ratio increases, but eventually stabilizing after a damped oscillation phase. Furthermore, in both cases a preferred driving direction was present, along which the entanglement degradation was minimal. The height of the transmission time asymptote depends on the angle between such preferred direction and the driving operator-direction, with driving directions farther from the preferred one generally resulting in smaller entanglement transmission times. The asymptotic behaviour of the figures of merit analyzed is controlled by the stationary states of the channel. The form of the entanglement transmission time reflects the form of the eigenvalues of the generator of the dynamics, while the precence of a preferred direction is a consequence of commutation properties of the generator operators. A natural direction for future research is extending the anlysis to the case of continuous variables system, which has been completely left out from the discussion. In particular, Gaussian quantum channels provide a natural candidate, also in sight of their applications in quantum optics