Generation of polarization entangled photon pairs by a single crystal interferometric source pumped by femtosecond laser pulses

Photon pairs, highly entangled in polarization have been generated under femtosecond laser pulse excitation by a type I crystal source, operating in a single arm interferometric scheme. The relevant effects of temporal walk-off existing in these conditions between the ordinary and extraordinary photons were experimentally investigated. By introducing a suitable temporal compensation between the two orthogonal polarization components highly entangled pulsed states were obtained

Hyperentanglement witness

A new criterium to detect the entanglement present in a {\it hyperentangled state}, based on the evaluation of an entanglement witness, is presented. We show how some witnesses recently introduced for graph states, measured by only two local settings, can be used in this case. We also define a new witness $W_3$ that improves the resistance to noise by increasing the number of local measurements.Comment: 6 pages, 2 figures, RevTex. v2: new title, minor changes in the explanation of the witness for hyperentangled states, more comments in the conclusions sectio

Generating qudits with d=3,4 encoded on two-photon states

We present an experimental method to engineer arbitrary pure states of qudits with d=3,4 using linear optics and a single nonlinear crystal.Comment: 4 pages, 1 eps figure. Minor changes. The title has been changed for publication on Physical Review

"All-versus-nothing" nonlocality test of quantum mechanics by two-photon hyperentanglement

We report the experimental realization and the characterization of polarization and momentum hyperentangled two photon states, generated by a new parametric source of correlated photon pairs. By adoption of these states an "all versus nothing" test of quantum mechanics was performed. The two photon hyperentangled states are expected to find at an increasing rate a widespread application in state engineering and quantum information. PACS: 03.65.Ud, 03.67.Mn, 42.65. LmComment: Replaced with published versio

Engineering a C-Phase quantum gate: optical design and experimental realization

A two qubit quantum gate, namely the C-Phase, has been realized by exploiting the longitudinal momentum (i.e. the optical path) degree of freedom of a single photon. The experimental setup used to engineer this quantum gate represents an advanced version of the high stability closed-loop interferometric setup adopted to generate and characterize 2-photon 4-qubit Phased Dicke states. Some experimental results, dealing with the characterization of multipartite entanglement of the Phased Dicke states are also discussed in detail.Comment: accepted for publication on EPJ

Legal aspects of marine science on climate change

Oceans and seas are key components in climate systems. The strong need for more specific knowledge and its systematic delivery and application, including in relation to climate effects on marine environment, led to the recent adoption of the the UN Decade of Ocean Science for Sustainable Development (2021-2030). From an international law of the sea perspective, the increasing marine scientific research activities and the use of novel technologies rise the question on the adequacy of the current applicable regulatory framework. This paper focuses on the main legal aspects of marine science on climate change and call for a paradigm-shift: from unilateralism to multilateralism in the interests of mankind

Mobility and Legal Migration in the Context of the European Neighbourbood Policy: What Role for the European Union?

The paper examines the evolution of the external dimension of EU immigration policy mainly in the context of European Neighbourhood policy (ENP). The EU is interested in countering irregular migration from Southern neighbours rather than in facilitating legal migration for third country nationals. The latter field falls within the competence of the EU Member States and they are reluctant to open legal migration channels. Only recently Mobility Partnerships (MPs) have been concluded with Morocco, Tunisia and Jordan. Most recently, the EU has decided to financially support countries of origin/transit in order to strengthen their capacity to tackle migration pressure; migration compacts will be negotiated not only with Southern neighbours but also with other African countries. In contrast to Southern neighbours, MPs were agreed with all Eastern neighbours, except Belarus; readmission agreements and visa-free agreements were concluded with three Eastern neighbour countries: Ukraine, Georgia and Moldova. The EU has fostered mobility and people-to-people movements in its relations with Eastern neighbours but the added value of EU legislation designed to favour legal migration and integration of third country nationals remain limited. The conclusion is that the EU continues to be a «fortress», especially for low-skilled migrants seeking an employment

Regional seas

Description of developments in regional seas regulatory framewor

Probe lifetime around natural satellites with obliquity

The dynamics of a probe orbiting a moon can be significantly influenced by the noncoincidence between the moon’s equatorial and orbital planes. Thus, we performed a general analysis about the effects of the angle (obliquity) between the above-mentioned planes and of the angle (nodal phasing) between the nodal lines of the mother planet’s apparent orbit and the probe orbit on the lifetime of the probe. The lifetime, strictly correlated to the variations in eccentricity of the probe orbit, was evaluated starting from low values of the semi-major axis, moderate eccentricity, and high inclination to offer high ground spatial resolution and extend latitudinal coverage of the natural satellite. This investigation, carried out through numerical simulations, may be useful for identifying the optimal initial conditions of the probe’s orbit elements, leading to an important increase in the probe lifetime in missions devoted to the exploration of natural satellite