Vertex Intrinsic Fitness: How to Produce Arbitrary Scale-Free Networks

We study a recent model of random networks based on the presence of an intrinsic character of the vertices called fitness. The vertices fitnesses are drawn from a given probability distribution density. The edges between pair of vertices are drawn according to a linking probability function depending on the fitnesses of the two vertices involved. We study here different choices for the probability distribution densities and the linking functions. We find that, irrespective of the particular choices, the generation of scale-free networks is straightforward. We then derive the general conditions under which scale-free behavior appears. This model could then represent a possible explanation for the ubiquity and robustness of such structures.Comment: 4 pages, 3 figures, RevTe

Investigation of mid-infrared AlInSb LEDs with an n-i-p structure

We report on the investigation on mid-infrared AlInSb LEDs with an n-i-p structure. Compared to the conventional AlInSb LEDs with a p-i-n structure, a better current spreading corresponding to a uniform current distribution in the active region is expected in the n-i-p structure because of a high electron mobility in the n-type AlInSb material. The output optical power of laterally injected LEDs were investigated as a function of the device geometry by COMSOL simulations and confirmed by experimental results

Narrow Linewidth 780 nm Distributed Feedback Lasers for Cold Atom Quantum Technology

Cold atom quantum technology systems have a wide range of potential applications which includes atomic clocks, rotational sensors, inertial sensors, quantum navigators, magnetometers and gravimeters. The UK Quantum Technology Hub in Sensors and Metrology has the aim of developing miniature cold atom systems using an approach similar to that pioneered by the chip scale atomic clock where microfabricated vacuum chambers have atomic transitions excited and probed by lasers. Whilst narrow linewidth Ti:Sa and external cavity diode lasers have been required for cooling and control, such lasers are too large, power hungry and expensive for future miniature cold atom systems. Here we demonstrate 1 mm long 780.24 nm GaAs/AlGaAs distributed feedback (DFB) lasers aimed at 87Rb cold atom systems operating at 20 ˚C with over 50 mW of power and side-mode suppression ratios of 46 dB using sidewall gratings and no regrowth. Rb spectroscopy is used to demonstrate linewidths below the required 6.07 MHz natural linewidth of the 87Rb D2 optical transition used for cooling. Initial packaged fibre-coupled devices demonstrate lifetimes greater than 200 hours. We also investigate the use of integrated semiconductor amplifiers (SOAs) and longer devices to further reduce the linewidths well below 1 MHz. A range of options to control the populations of electrons in the hyperfine split energy levels spaced by 3.417 GHz are examined. Two integrated lasers, integrated electro-absorption modulators (EAMs) and the direct modulation of a single DFB laser approaches are investigated and we will discuss which is best suited to integrated cold atom systems

The Orbital Angular Momentum of Light for Ultra-High Capacity Data Centers

The potential of orbital angular momentum (OAM) of light in data center scenarios is presented. OAMs can be exploited for short reach ultra-high bit rate fiber links and as additional multiplexing domain in transparent ultra-high capacity optical switches. Recent advances on OAM integrated photonic technology are also reported. Finally demonstration of OAM-based fiber links (aggregate throughput 17.9 Tb/s) and two layers OAM-WDM-based optical switches are presented exploiting OAM integrated components and demonstrating the achievable benefits in terms of size, weight and power consumption (SWaP) compared to different technologies

Realization of quantum walks with negligible decoherence in waveguide lattices

Quantum random walks are the quantum counterpart of classical random walks, and were recently studied in the context of quantum computation. Physical implementations of quantum walks have only been made in very small scale systems severely limited by decoherence. Here we show that the propagation of photons in waveguide lattices, which have been studied extensively in recent years, are essentially an implementation of quantum walks. Since waveguide lattices are easily constructed at large scales and display negligible decoherence, they can serve as an ideal and versatile experimental playground for the study of quantum walks and quantum algorithms. We experimentally observe quantum walks in large systems (similar to 100 sites) and confirm quantum walks effects which were studied theoretically, including ballistic propagation, disorder, and boundary related effects

Using geomorphic and biological indicators of coastal uplift for the evaluation of paleoseismicity and

The westernmost part of the Gulf of Corinth (Greece) is an area of very fast extension (~15 mm/yr according to geodetic measurements) and active normal faulting, accompanied by intense coastal uplift and high seismicity. This study presents geomorphic and biological evidence of Holocene coastal uplift at the western extremity of the Gulf, where such evidence was previously unknown. Narrow shore platforms (benches) and rare notches occur mainly on Holocene littoral conglomerates of uplifting small fan deltas. They are perhaps the only primary paleoseismic evidence likely to provide information on earthquake recurrence at coastal faults in the specific part of the Rift system, whereas dated marine fauna can provide constraints on average Holocene coastal uplift rate. The types of geomorphic and biological evidence identified are not ideal, and there are limitations and pitfalls involved in their evaluation. In a first approach, 5 uplifted paleoshorelines may be indentified, at 0.4- 0.7, 1.0-1.3, 1.4-1.7, 2.0-2.3 and 2.8-3.4 m a.m.s.l. They probably formed after 1728 or 2250 Cal. B.P. (depending on the marine reservoir correction used in the calibration of measured radiocarbon ages). A most conservative estimate for the average coastal uplift rate during the Late Holocene is 1.6 or 1.9 mm/yr minimum (with different amounts of reservoir correction). Part of the obtained radiocarbon ages of Lithophaga sp. allows for much higher Holocene uplift rates, of the order of 3-4 mm/yr, which cannot be discarded given that similar figures exist in the bibliography on Holocene and Pleistocene uplift at neighbouring areas. They should best be cross-checked by further studies though. That the identified paleoshoreline record corresponds to episodes of coastal uplift only, cannot be demonstrated beyond all doubt by independent evidence, but it appears the most likely interpretation, given the geological and active-tectonic context and, what is known about eustatic sea-level fluctuations in the Mediterranean. Proving that the documented uplifts were abrupt (i.e., arguably coseismic), is equally difficult, but reasonably expected and rather probable. Five earthquakes in the last ca. 2000 yrs on the coastal fault zone responsible for the uplift, compare well with historical seismicity and the results of recent on-fault paleoseismological studies at the nearby Eliki fault zone. Exact amounts of coseismic uplift cannot be determined precisely, unless the rate of uniform ("regional") non-seismic uplift of Northern Peloponnesus at the specific part of the Corinth Rift is somehow constrained

Leptonic CP violation studies at MiniBooNE in the (3+2) sterile neutrino oscillation hypothesis

We investigate the extent to which leptonic CP-violation in (3+2) sterile neutrino models leads to different oscillation probabilities for $\bar{\nu}_{\mu}\to\bar{\nu}_e$ and $\nu_{\mu}\to\nu_e$ oscillations at MiniBooNE. We are using a combined analysis of short-baseline (SBL) oscillation results, including the LSND and null SBL results, to which we impose additional constraints from atmospheric oscillation data. We obtain the favored regions in MiniBooNE oscillation probability space for both (3+2) CP-conserving and (3+2) CP-violating models. We further investigate the allowed CP-violation phase values and the MiniBooNE reach for such a CP violation measurement. The analysis shows that the oscillation probabilities in MiniBooNE neutrino and antineutrino running modes can differ significantly, with the latter possibly being as much as three times larger than the first. In addition, we also show that all possible values of the single CP-violation phase measurable at short baselines in (3+2) models are allowed within 99% CL by existing data.Comment: Fixed a typo following PRD Erratum. 8 pages, 5 figure

Geomorphological, stratigraphic and geochronological evidence of fast Pleistocene coastal uplift in the westernmost part of the Corinth Gulf Rift (Greece)

Rapid extension and active normal faulting in the western extremity of the Corinth Gulf are accompanied by fast coastal uplift.We investigate Pleistocene uplift west of Aigion, by attempting to date remains of marine terraces and sedimentary sequences by calcareous nannoplankton and U-series analyses. Net uplift initiated recently, due to abandonment of an older rift-bounding fault zone and increase in activity on the presently active, coastal fault zone. This change apparently coincides with an abrupt slow down (or, termination) of secondary fault block tilting within the broader hangingwall block of the older zone, indicated by an angular unconformity that dates in the early part ofMIS10 ( 390–350 ka BP, preferably, in the earlier part of this period). Net uplift driven by the coastal zone resulted in the formation of MIS9c (330 ka) and younger terraces. The formation of the unconformity and the initiation of net uplift coincide temporally with a 300–400 ka unconformity recognized by recent studies in a wide area offshore Aigion i.e. they could be part of an evolutionary event that affected the entirewestern part of the Corinth Rift or, a large area therein. Uplift rate estimates at four locations are discussed with reference to the morphotectonic context of differential uplift of secondary fault blocks, and the context of possible increase in uplift ratewith time. Themost reliable and most useful estimate for uplift rate at the longitude of the studied transect is 1.74–1.85mm/year (time-averaged estimate for the last 240 ka, based on calcareous nannoplankton and sequence-stratigraphic interpretation

The Future of Neutrino Mass Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the Next Decade. Highlights of the NuMass 2013 Workshop. Milano, Italy, February 4 - 7, 2013

The third Workshop of the NuMass series ("The Future of Neutrino Mass Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the Next Decade: NuMass 2013") was held at Dipartimento di Fisica "G. Occhialini, University of Milano-Bicocca in Milano, Italy, on 4-7 February 2013. The goal of this international workshop was to review the status and future of direct and indirect neutrino mass measurements in the laboratory as well as from astrophysical and cosmological observations. This paper collects most of the contributions presented during the Workshop