November 2021 - news - Mailing lists@ IFISC

IFISC News - IFISC People: Lucas Lacasa
by ifisc＠ifisc.uib-csic.es 30 Nov '21

30 Nov '21

IFISC People: Lucas Lacasa We are pleased to announce that Prof. Lucas Lacasa joins IFISC as a CSIC Tenured Scientist. Lucas was previously Reader in Applied Mathematics at the School of Mathematical Sciences, Queen Mary University of London (UK) as well as an associate fellow at Kings College London and an EPSRC Early Career Fellow. He has received several academic distinctions, including the 2019 International Prize on Formal Sciences awarded by USERN and the Research Excellence Award from QMUL (2020). In the past he was a guest scientist at UCLA and Oxford, and currently serves in various editorial boards such as PLoS ONE or Entropy. His research focuses on building on his background in nonlinear dynamics, statistical physics and network theory to develop methods for data analysis, and is interested in both fundamental aspects of complexity science as well as in their applications to biological and socio-technical systems. He has published about 80 papers in areas spanning multidisciplinary science (PNAS, Nature Communications), physics (Physical Review X, Physical Review Letters), mathematics (Nonlinearity) or computer science (IEEE TPAMI), and his research has been highlighted in the press over 150 times. In a previous life, he tried to be a musician. Apparently his last band only really took off and reached popularity once he left, probably a good indicator that he made the right decision in choosing science. Still, he loves music and is generally interested in the interface between art and science. http://ifisc.uib-csic.es/en/news/ifisc-people-lucas-lacasa/

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IFISC News - In quantum mechanics, not even time flows as you might expect
by ifisc＠ifisc.uib-csic.es 26 Nov '21

26 Nov '21

In quantum mechanics, not even time flows as you might expect A team of physicists at the Universities of Vienna, Bristol, IFISC and the Institute for Quantum Optics and Quantum Information (IQOQI-Vienna) has shown how quantum systems can simultaneously evolve along two opposite time arrows (forward and backward in time). The study has been published in the latest issue of Communications Physics.Forward and backward time flowsWhen looking at the celestial motion, one often perceives a sense of eternity that could lead us to wonder whether time really exists after all. On the other hand, looking back at our daily lives extinguishes all doubts: time exists and moves forward. This apparent certainty comes from the fact that most macroscopic physical phenomena can only ever occur in one direction. Take the sequence of things we do in our morning routine, for example. If one were to show us our toothpaste moving from the toothbrush back into its tube, we would know without a doubt that they were just showing us the rewind of the recording of our day. In physics, this propensity of certain phenomena to occur in only one time's direction is linked to their production of ‘entropy’, which is the physical quantity defining the amount of disorder in a system. In nature, processes tend to evolve spontaneously from states with less disorder to states with more disorder, and this propensity can be used to identify an arrow of time. Thus, if a phenomenon produces a large amount of entropy, observing its time-reversal is so improbable as to become essentially impossible. However, when the entropy produced is small enough, there is a non-negligible probability of seeing the time-reversal of a phenomenon occur naturally. Thinking back to the toothpaste example, if we were to squeeze the tube only gently and only a very small part of the toothpaste came out, it would not be so unlikely to observe it re-entering the tube, sucked in by the tube’s decompression. On the other hand, as the tube is squeezed with more strength, the toothpaste will spread out in an irreversible way, requiring a much greater effort if one were to put all it back in.The boundary between forward and backward blurs in quantum mechanicsA team of physicists at the Universities of Vienna, Bristol, IFISC (UIB-CSIC) and IQOQI-Vienna, under the lead of Časlav Brukner, has applied this idea to the quantum realm, seeking to gain a deeper understanding of how time flows in that regime. One of the peculiarities of the quantum world is the principle of quantum superposition, according to which if two states of a quantum system are both possible, then that system can also be in both states at the same time. If we look back at the system evolving in one or the other temporal direction (the toothpaste coming out of or going back into the tube), it results that quantum systems can also find themselves evolving simultaneously along both temporal directions. Although this idea seems rather nonsensical when applied to our day-to-day experience, at its most fundamental level, the laws of the universe are based on quantum-mechanical principles. This begs the question of why we never encounter these superpositions of time flows in nature. “In our work, we quantified the entropy produced by a system evolving in quantum superposition of processes with opposite time arrows. We found that this most often results in projecting the system onto a well-defined time’s direction, corresponding to the most likely process of the two” explains Gonzalo Manzano, a co-author of the study. And yet, when small amounts of entropy are involved (for instance, when there is so little toothpaste spilled that one could see it being reabsorbed into the tube), then one can physically observe the consequences of the system having evolved along the forward and backward temporal directions at the same time. As pointed out by Giulia Rubino, lead-author of the publication, “although time is often treated as a continuously increasing parameter, our study shows that the laws governing its flow in quantum mechanical contexts are much more complex. This may suggest that we need to rethink the way we represent this quantity in all those contexts where quantum laws play a crucial role.”“Quantum superposition of thermodynamic evolutions with opposing time’s arrows” in Communications Physics. DOI: 10.1038/s42005-021-00759-1Artistic illustration of a gondolier trapped in a quantum superposition of time flows. Credit: © Aloop Visual & Science, University of Vienna, Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences http://ifisc.uib-csic.es/en/news/quantum-mechanics-not-even-time-flows-you-…

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IFISC News - Voces, CSIC Balears: Complex networks, mathematical chemistry and COVID
by ifisc＠ifisc.uib-csic.es 17 Nov '21

17 Nov '21

Voces, CSIC Balears: Complex networks, mathematical chemistry and COVID IFISC (UIB-CSIC) and the Institutional Representation of CSIC in the Balearic Islands join forces and create "Voces, CSIC Balears", a bimonthly podcast for the dissemination of science. Through interviews with scientists working at CSIC's centres in the Balearic Islands (IMEDEA CSIC-UIB, IFISC UIB-CSIC and ICTS SOCIB), it aims to increase the visibility of the science carried out in the region. The 15th episode of "Voices, CSIC Balears" features Ernesto Estrada. Ernesto is a research professor at IFISC and in addition to writing several books on complex network theory, he has published more than 220 papers that have received more than 15000 citations on topics as diverse as applied biomedicine, mathematical chemistry or networks applied to social systems. Ernesto was elected honorary member of the Society for Industrial and Applied Mathematics in 2019 and of the Latin American Academy of Sciences also in 2019, Member of the Academia Europeae in 2014, and of the International Academy of Mathematical Chemistry in 2004.Redes complejas, química matemática y COVID | VOCES, CSIC BALEARS #15 http://ifisc.uib-csic.es/en/news/voces-csic-balears-complex-networks-mathem…

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IFISC News - Boosting the output power of lasers by breaking their symmetry
by ifisc＠ifisc.uib-csic.es 11 Nov '21

11 Nov '21

Boosting the output power of lasers by breaking their symmetry More uniform light intensity profiles are possible in large-aperture semiconductor lasers if the optical aperture is intentionally deformed. An international team from Łodz University of Technology, Institute of Microelectronics and Photonics in Warsaw, Technical University of Berlin, and IFISC (UIB-CSIC) present these findings in Optica [1]. Moreover, the research has been highlighted in the ‘News and Views’ section in the November issue of the prestigious journal Nature Photonics [2]. Since lasers were invented, there have been continual efforts to increase their emitted optical power. In general, such efforts have been focused on increasing the size of the region in which stimulated emission occurs or increasing the efficiency of photon generation in that region. Here, the researchers show that intentionally deformed optical apertures induce a spatially more uniform light intensity distribution of broad-area vertical-cavity surface-enhanced lasers (VCSEL) and a higher density of optical states. This, in turn, enhances the stimulated emission of photons as predicted by quantum electrodynamics theory. To demonstrate this, they first proposed four classes of VCSEL, each with different oxide apertures of symmetry-broken shapes that slightly increase the aperture area. They named the shapes according to the resemblance of the resulting beam profiles with racket shapes used in sports: ball, ping-pong, padel, squash, and tennis, each one with differing side deformations. These deformations break the symmetry of the circular shape aperture leaving only one mirror symmetry. As a consequence, the light density is more uniformly distributed, and the optical modes experience less gain competition, increasing the probability of stimulated emission and, because of that, the number of electrons recombining per unit of time is also increased. This overall process reduces the heating of the lasers, and a higher maximal emitted optical power is obtained. Although the aperture area was only 6% larger, the team achieved an increase in output power up to 60% and in quantum efficiency of 10%. To cite the authors from the paper: “Our asymmetric ‘ugly ducklings’ become ‘beautiful swans’ shining much more brightly.” The researchers claim that the possibility of boosting the emitted power by symmetry breaking may apply to other high-power lasers in which circular apertures are commonly used, such as broad-area edge-emitting lasers, solid-state lasers, multimode-fiber lasers, and amplifiers. Future works will focus on determining the optimal oxide aperture shapes expected to enhance the emitted power by design. [1] A. Brejnak, M. Gębski, A. K. Sokół, M. Marciniak, M. Wasiak, J. Muszalski, J. A. Lott, I. Fischer, and T. Czyszanowski, "Boosting the output power of large-aperture lasers by breaking their circular symmetry," Optica 8, 1167-1175 (2021). https://doi.org/10.1364/OPTICA.421753 [2] O. Graydon, “Asymmetry brings power boost,” Nature Photon. 15, 795 (2021). https://doi.org/10.1038/s41566-021-00899-4 El Diari de la UIB http://ifisc.uib-csic.es/en/news/boosting-output-power-lasers-breaking-thei…

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IFISC News - IFISC and IMEDEA organize the V Symposium on Ecological Networks
by ifisc＠ifisc.uib-csic.es 09 Nov '21

09 Nov '21

IFISC and IMEDEA organize the V Symposium on Ecological Networks Researchers from IFISC and IMEDEA organize the V Symposium on ecological networks (ECONET) in Palma. The event will be held between November 10 and 12, and will bring together, for the first time, biologists and theoretical physicists who work on network theory or use it as an approach to understand the structure and functioning of biological communities. ECONET is defined as an excellent opportunity to share methodologies and results between these two approaches to the study of ecological networks and aims to serve as a platform to develop joint future projects. Among the numerous presentations by researchers from all over the world, the keynote speakers will be Mercedes Pascual (University of Chicago), Yamir Moreno (Universidad de Zaragoza), Shai Pilosof (Ben-Gurion University of the Negev), Carlos Melián (Swiss Federal Institute of Aquatic Science and Technology) and Anna Eklöf (Linköping University). The symposium will also offer the informative talk on the ecological changes that marine ecosystems are undergoing entitles Ecosistemas complejos y transiciones críticas en nuestros mares cambiantes. The talk will be given by the researcher Mercedes Pascual in the Auditorium Hall of the Caixa Forum in Palma on Wednesday 10 at 19 pm. http://ifisc.uib-csic.es/en/news/ifisc-and-imedea-organize-v-symposium-ecol…

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