Production of optical phase space vortices with non-locally distributed mode converters

Optical vortices have been observed in a wide variety of optical systems. They can be observed directly in the wavefront of optical beams, or in the correlations between pairs of entangled photons. We present a novel optical vortex which appears in a non-local plane of the two-photon phase space, composed of a single degree of freedom of each photon of an entangled pair. The preparation of this vortex can be viewed as a "non-local" or distributed mode converter. We show how these novel optical vortices of arbitrary order can be prepared in the spatial degrees of freedom of entangled photons.Comment: To appear in upcoming special issue "Orbital Angular Momentum" of the Journal of Optic

Single observable concurrence measurement without simultaneous copies

We present a protocol that allows us to obtain the concurrence of any two qubit pure state by performing a minimal and optimal tomography of one of the subsystems through measuring a single observable of an ancillary four dimensional qudit. An implementation for a system of trapped ions is also proposed, which can be achieved with present day experimental techniques.Comment: 4 pages, 1 figur

Does a new research-funding model ask for a new evaluation framework? The case of Serrapilheira in Brazil

The purpose of this manuscript is to present an on-going experience of impact evaluation applied to a recently created S&T funding agency. The Institute Serrapilheira (ISP) is a private nonprofit organization created to fund new and challenging themes of research. Serrapilheira brings innovation to the Brazilian scenario of science funding in at least three directions. First, ISP is the first family-philanthropically funded organization totally dedicated to support science in Brazil. Secondly, as a private institution, it can provide researchers with greater flexibility in terms of resource allocation comparing to public funding agencies. The 2018 estimated budget is US$ 4,5 million. Thirdly, in its first call for proposals launched in mid-2017, ISP asked young researchers to present proposals out of the “Normal Science”. The definition of the impact evaluation model of the first call of Serrapilheira was based on both the institutional model proposed by the organization – and its main purposes – as well as on the particular goals of the first call. As a first step, these objectives were discussed with Serrapilheira’s staff. The second step consisted of detecting evaluation hypotheses, themes and indicators based on the discussion of the model’s objectives. As a result, six evaluation themes were defined – one oriented to characterizing the grantees both in terms of diversity and academic training and the other five oriented to measure impacts: (i) professional trajectory, (ii) scientific and technology production, (iii) night science, (iv) insertion and prominence and (v) research culture. Traditional and widely accepted indicators of scientific and technological impact were used, even for dialogue with communities and scientific institutions and terms of comparison. Nevertheless, the main challenge was to identify indicators that allow the measurement of variables that directly or indirectly approach the particularities of the research-funding model. As a first remark, we understand that the particularities of the new research-funding model proposed by ISP asks for a new evaluation framework, more oriented to alternative indicators and to a broad perspective about outputs, outcomes and impacts in a more diverse and multifaceted research system. In this current hands-on impact-study a methodology is being built and simultaneously applied to a concrete case. This experience may contribute to the field of impact evaluation to the extent it proposes not only alternative indicators to be mixed with traditional ones, but also because it has a longitudinal perspective of following grantees since the inception (with the advantage of starting with a baseline) till two years after projects end, performing a 5-year long evaluation. Another possible contribution refers to the understanding about the ways funding agencies are evaluating the outcomes and impacts of their initiatives

Experimental Observation of Environment-induced Sudden Death of Entanglement

We demonstrate the difference between local, single-particle dynamics and global dynamics of entangled quantum systems coupled to independent environments. Using an all-optical experimental setup, we show that, while the environment-induced decay of each system is asymptotic, quantum entanglement may suddenly disappear. This "sudden death" constitutes yet another distinct and counter-intuitive trait of entanglement.Comment: 4 pages, 4 figure

Entropic Entanglement Criteria for Continuous Variables

We derive several entanglement criteria for bipartite continuous variable quantum systems based on the Shannon entropy. These criteria are more sensitive than those involving only second-order moments, and are equivalent to well-known variance product tests in the case of Gaussian states. Furthermore, they involve only a pair of quadrature measurements, and will thus should prove extremely useful the experimental identification of entanglement.Comment: 4 pages, 2 figure