Abstract:
The state of spatially correlated down-converted photons is usually treated as a two-mode Gaussian entangled state. While intuitively this seems to be reasonable, it is known that new structures in the spatial distributions of these photons can be observed when the phase-matching conditions are properly taken into account. Here, we study how the variances of the near- and far-field conditional probabilities are affected by the phase-matching functions, and we analyze the role of the EPR-criterion regarding the non-Gaussianity and entanglement detection of the spatial two-photon state of spontaneous parametric down-conversion (SPDC). Then we introduce a statistical measure, based on the negentropy of the joint distributions at the near- and far-field planes, which allows for the quantification of the non-Gaussianity of this state. This measure of non-Gaussianity requires only the measurement of the diagonal covariance sub-matrices, and will be relevant for new applications of the spatial correlation of SPDC in CV quantum information processing.

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hata el momento no he podido subir mis publicaciones

Pollution is a problem that seriously affects a large part of our planet, and that is why every day new forms and technologies are sought to measure it. Thus, new measures to mitigate it are generated, as for example, defining latent zones of pollution. LIDAR is one of the scientific techniques used to measure this problem, and it is being used more and more.

Dr. Montilla pointed out that the importance of this technique lies not only in the details that allow us to know about the evolution of atmospheric composition, but also from a social point of view, “due to the great importance that is currently placed on knowing the evolution of air pollution in these times that we are living.”

For Dr. Carlos Saavedra, Scientific Director of CEFOP, this school offers the possibility to generate very concrete possibilities of collaboration with other South American researchers in LIDAR technology, particular those from Argentina, Brazil and Colombia. “We are interested in talking with them, and discussing long-term programs, where our LIDAR laboratory is incorporated into the world-wide program of LIDAR observations in themes which they are concentrating on.”

But at the same time, Saavedra noted, “We would like for our students, at the University of Concepción and those that visit us, to have the possibility of getting to know each other and to participate in these types of activities so they can take part in future challenges. Today we have begun discussions of some complementary programs of collaboration, not only with LIDAR, but also with DOAS technology, where we will probably initiate a collaboration with Argentina, with researchers headed by Dr. Elián Wolfram.”

How to approach this technology, its implications, and its evolution is what is being developed in the V Summer School on Optics and Photonics, organized by the Center for Optics and Photonics (CEFOP) at the University of Concepcíon, financed by the Basal Program of Conicyt. Their applications are of great scientific and social relevance in the study of air pollution and its effects, explained one of their organizers, Dr. Elena Montilla, who also is a researcher at the LIDAR laboratory of CEFOP.

STRONG EVOLUTION

Dr. Elián Wolfram is one of the top specialists of the LIDAR technique in Argentina, and he is a member of the Center for Laser Research and Applications in that trans-Andean country. On his first day of Summer School, he assured us that this is a “fantastic initiative of CEFOP, because it allows for the creation of ties between communities in the Americas, especially in Latin America, which we need to reinforce.”

He added that Chile has grown considerably, and took as an example the Center for Optics and Photonics of UdeC, where he emphasized that in the capacity for experimental development, there “really is a quantum leap. Universities of excellence in the world easily carry out theoretical physics, but not experimental physics, and here we see a demonstration that the experimental part, from the application of its knowledge, has taken on an important role.”

With respect to LIDAR technology, he emphasized that it is already an important instrument for observations of phenomena with great social impact, “like the ozone layer, urban pollution or, in general, the volcanic eruptions that are currently affecting us. Thus, LIDAR is becoming a tool of almost daily use, in research groups or centers that need this information with a high degree of accuracy.”

HOW IT WORKS

Dr. Alvaro Bastidas, from the Spectroscopy Laser Group of the National University of Colombia, pointed out that the operation principle of LIDAR systems is based on sending a pulsed laser beam into the atmosphere, and in the analysis of a fraction of the radiation retro disseminated by existing atmospheric particles, throughout the optical path crossed by the short pulses of laser light. “This small amount of light that returns towards the point from which the laser shot it, is gathered by a telescope and is detected.”

Then, he continued, after a delicate and complex processing of these signals, “It is already possible to obtain valuable data on the spatial distribution of particles throughout the trajectory followed by the laser light, as well as a characterization of relevant atmospheric optical parameters associated with known atmospheric particles like aerosols.”

According to Bastidas, a LIDAR instrument works like an authentic optical radar, “whose design and practical use is concentrated on the study of atmospheric particulates, whose role in Earth energy outcomes and their implications for future climatic conditions is an important current research topic.”

Pollution is a problem that seriously affects a large part of our planet, and that is why every day new forms and technologies are sought to measure it. Thus, new measures to mitigate it are generated, as for example, defining latent zones of pollution. LIDAR is one of the scientific techniques used to measure this problem, and it is being used more and more.

Dr. Montilla pointed out that the importance of this technique lies not only in the details that allow us to know about the evolution of atmospheric composition, but also from a social point of view, “due to the great importance that is currently placed on knowing the evolution of air pollution in these times that we are living.”

For Dr. Carlos Saavedra, Scientific Director of CEFOP, this school offers the possibility to generate very concrete possibilities of collaboration with other South American researchers in LIDAR technology, particular those from Argentina, Brazil and Colombia. “We are interested in talking with them, and discussing long-term programs, where our LIDAR laboratory is incorporated into the world-wide program of LIDAR observations in themes which they are concentrating on.”

But at the same time, Saavedra noted, “We would like for our students, at the University of Concepción and those that visit us, to have the possibility of getting to know each other and to participate in these types of activities so they can take part in future challenges. Today we have begun discussions of some complementary programs of collaboration, not only with LIDAR, but also with DOAS technology, where we will probably initiate a collaboration with Argentina, with researchers headed by Dr. Elián Wolfram.”

How to approach this technology, its implications, and its evolution is what is being developed in the V Summer School on Optics and Photonics, organized by the Center for Optics and Photonics (CEFOP) at the University of Concepcíon, financed by the Basal Program of Conicyt. Their applications are of great scientific and social relevance in the study of air pollution and its effects, explained one of their organizers, Dr. Elena Montilla, who also is a researcher at the LIDAR laboratory of CEFOP.

STRONG EVOLUTION

Dr. Elián Wolfram is one of the top specialists of the LIDAR technique in Argentina, and he is a member of the Center for Laser Research and Applications in that trans-Andean country. On his first day of Summer School, he assured us that this is a “fantastic initiative of CEFOP, because it allows for the creation of ties between communities in the Americas, especially in Latin America, which we need to reinforce.”

He added that Chile has grown considerably, and took as an example the Center for Optics and Photonics of UdeC, where he emphasized that in the capacity for experimental development, there “really is a quantum leap. Universities of excellence in the world easily carry out theoretical physics, but not experimental physics, and here we see a demonstration that the experimental part, from the application of its knowledge, has taken on an important role.”

With respect to LIDAR technology, he emphasized that it is already an important instrument for observations of phenomena with great social impact, “like the ozone layer, urban pollution or, in general, the volcanic eruptions that are currently affecting us. Thus, LIDAR is becoming a tool of almost daily use, in research groups or centers that need this information with a high degree of accuracy.”

HOW IT WORKS

Dr. Alvaro Bastidas, from the Spectroscopy Laser Group of the National University of Colombia, pointed out that the operation principle of LIDAR systems is based on sending a pulsed laser beam into the atmosphere, and in the analysis of a fraction of the radiation retro disseminated by existing atmospheric particles, throughout the optical path crossed by the short pulses of laser light. “This small amount of light that returns towards the point from which the laser shot it, is gathered by a telescope and is detected.”

Then, he continued, after a delicate and complex processing of these signals, “It is already possible to obtain valuable data on the spatial distribution of particles throughout the trajectory followed by the laser light, as well as a characterization of relevant atmospheric optical parameters associated with known atmospheric particles like aerosols.”

According to Bastidas, a LIDAR instrument works like an authentic optical radar, “whose design and practical use is concentrated on the study of atmospheric particulates, whose role in Earth energy outcomes and their implications for future climatic conditions is an important current research topic.”

Whoever is interested should contact the following researchers:

Topic:  “Defocusing microscopy for the study of biological membranes”

Dr. María José Gallardo

Email: mgallardo@cefop.udec.cl

Phono: (56 + 041)-2661339 / (56 + 041) – 2661371

_______________________________________________________________________________________

Topic:  “Optics and thermodynamic studies in microscopic systems”

Dr. Juan Pablo Staforelli

Email: juanpablo.staforelli@cefop.udec.cl

Phono: (56 + 041)-2661339 / (56 + 041)-2661371

Dr. Sajeev John is admired by his peers in physics around the world, and not just because he has been a step away from the Nobel three times, but because his research has already made revolutionary strides in the world of computation, after the construction of materials that could be used to create computer chips that function a thousand times faster while spending less energy.

These materials are known as “photonic crystals,” which for years much of Sajeev John’s work has been based on; first, creating a theoretical framework for these special materials that can trap light at the level of wave longitudes used in fiber optics for telecommunications, and later, building this material for the first time together with a group of experts in materials and chemistry. This experience and its evolution is what John shared with the members of the Center for Optics and Photonics (CEFOP) at the University of Concepción, after touring the laboratories of the Center and getting to know the city.  “I’ve been left with a very good impression of this Center, with what you are developing here, and the applications in distinct areas,”  the researcher noted.

This creation has crossed much of Sajeev John’s academic life, beginning with his doctoral thesis at Harvard, which included the presentation of the theoretical framework of photonic crystals.  This was later refined during his work at Princeton, in order to become reality at his current academic home, the University of Toronto.  Thus, he and his colleagues have been improving the theory and experimental techniques for the generation of these materials with the capacity to trap light.

According to Sajeev John, photonic crystals can have multiple applications, for example in such areas as telecommunications-specifically as a substitute for fiber optics in the production of more powerful and rapid computers-and including the use of crystals for laser surgery, where it would no longer be necessary to make physical incisions.  John added that for several years now many countries are already working with this material in the search for solutions in diverse areas.

What are they?

According to the explanation given by Sajeev John, the best way to know what photonic crystals are is to understand that light escapes easily and the point is to manage to make an ideal “cage” to contain it and restrict its various channels of escape.  This is where photonic crystals come in because, in short, they are basically a cage for light that conducts it into their interior.

The work, titled “Hyperspectral study of Mulinia edulis and Edotea magellanica for optical discrimination purposes,” is aimed at establishing characteristics by optical methods that allow for the detection of parasites in biological systems, and that suggest possible solutions for the industry. “Mulinia edulis is a type of clam that sometimes carries a parasite, called Edotea magellanica, which becomes a problem for the seafood industry since each clam must be opened and inspected one by one before its commercialization, hindering the whole process,” Pablo explained. In this work, “We found a spectral curve that, after 720 nanometers, allows the detection of this parasite by image processing,”  he added.  On a more personal level, the researcher stated that his next plan is focussed on pursuing a doctoral degree in electrical engineering.