February 2022 - semfis - Mailing lists@ IFISC

IFISC Seminar on Wednesday, Mar 02, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 25 Feb '22

25 Feb '22

IFISC Seminar on Wednesday Mar 02, 2022 at 14:30 Place: Zoom Seminar Title: Benchmarking experimental quantum computation: rigorous noise analysis in the simulation of dissipative collective effects Speaker: Marco Cattaneo, IFISC and University of Helsinki Abstract: &nbsp;In the era of near-term quantum computers, understanding the features of noise in quantum devices is essential to benchmark and improve the accuracy of quantum simulation algorithms. Here, we present an in-depth comparison between the results of a rigorous noise analysis of a near-term quantum computer and the outcomes of the &nbsp;first fully quantum experimental simulation of dissipative collective effects, the relevance of which ranges from the study of entanglement in biological systems to the engineering of dissipative phase transitions and quantum synchronization. We show that the conclusions drawn from the noise analysis crucially improve our understanding of the dynamics we are actually implementing on the quantum computer, and that the widely employed randomized benchmarking procedure may not always be reliable to detect faulty gates in the algorithm. Zoom:&nbsp;<a href="https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09">https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09</a> Url event:https://ifisc.uib-csic.es/en/events/seminars/benchmarking-experimental-quantum-computation-rigo/

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Reminder: IFISC Seminar, TODAY - Wednesday, Feb 23, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 23 Feb '22

23 Feb '22

IFISC Seminar on Wednesday Feb 23, 2022 at 14:30 Place: IFISC Seminar Room Title: Excursions through network theory Speaker: Ernesto Estrada, IFISC Abstract: I will give a panoramic view of some of my research topics which are currently active. These include: (1) the study of communicability functions on networks and their Euclidean geometric embedding; (2) the study of time-and-space nonlocal hops in networks and the emergence of sub- and superdiffusion; (3) the study of degree-biased Laplacians on networks and the emergence of advective-diffusive processes; (4) fractional calculus approaches to network theory. These topics will then be developed in details in a series of IFISC talks to be announced. Presential seminar, also to be streamed on Zoom: <a href="https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09">https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09</a> Url event:https://ifisc.uib-csic.es/en/events/seminars/excursions-through-network-theory/

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Reminder: Talk, TODAY - Tuesday, Feb 22, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 22 Feb '22

22 Feb '22

Talk on Tuesday Feb 22, 2022 at 14:30 Place: Zoom Seminar Title: How can the structure of ecosystems predict species' survival? Speaker: Violeta Calleja Solanas, IFISC (CSIC-UIB) Abstract: Abstract: Understanding the characteristics that promote ecosystems&rsquo; resilience is crucial to explain and protect biodiversity. In this picture, environmental changes may alter species interactions, leading to cascade extinctions. For this reason, determining which species are more prone to initiate cascades is of paramount importance. Here, we study the structural features of ecological networks that better predict species&rsquo; survival when the strength of their interactions is varied. Employing the replicator equation as a proxy for species dynamics, we find that a high eigenvector centrality is a key factor for survival in mutualistic networks. This result reinforces the importance of the species&rsquo; neighbors identity and the existence of positive feedback that prevent ecosystem collapse. This panorama changes with competitive interactions. In that case, the species that go extinct by extinctions cascades are determined not by their low eigenvector centrality but by a high degree. When both competitive and mutualistic interactions are considered, the behavior of the system is richer. Under those circumstances, not only networks are more resilient but eigenvector centrality and degree alone cannot fully predict species fate. Other individual properties such as the ratio between mutualistic and competitive interactions also play a fundamental role. Zoom link:&nbsp;&nbsp; https://us02web.zoom.us/j/87316222390?pwd=RG1qSG14TVA4aVBwNFBhRXAxNExWQT09&… Url event:https://ifisc.uib-csic.es/en/events/seminars/how-can-the-structure-of-ecosystems-predict-specie/

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Talk on Tuesday, Feb 22, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 18 Feb '22

18 Feb '22

Talk on Tuesday Feb 22, 2022 at 14:30 Place: Zoom Seminar Title: How can the structure of ecosystems predict species' survival? Speaker: Violeta Calleja Solanas, IFISC (CSIC-UIB) Abstract: Abstract: Understanding the characteristics that promote ecosystems&rsquo; resilience is crucial to explain and protect biodiversity. In this picture, environmental changes may alter species interactions, leading to cascade extinctions. For this reason, determining which species are more prone to initiate cascades is of paramount importance. Here, we study the structural features of ecological networks that better predict species&rsquo; survival when the strength of their interactions is varied. Employing the replicator equation as a proxy for species dynamics, we find that a high eigenvector centrality is a key factor for survival in mutualistic networks. This result reinforces the importance of the species&rsquo; neighbors identity and the existence of positive feedback that prevent ecosystem collapse. This panorama changes with competitive interactions. In that case, the species that go extinct by extinctions cascades are determined not by their low eigenvector centrality but by a high degree. When both competitive and mutualistic interactions are considered, the behavior of the system is richer. Under those circumstances, not only networks are more resilient but eigenvector centrality and degree alone cannot fully predict species fate. Other individual properties such as the ratio between mutualistic and competitive interactions also play a fundamental role. Zoom link:&nbsp;&nbsp; https://us02web.zoom.us/j/87316222390?pwd=RG1qSG14TVA4aVBwNFBhRXAxNExWQT09&… Url event:https://ifisc.uib-csic.es/en/events/seminars/how-can-the-structure-of-ecosystems-predict-specie/

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IFISC Seminar on Wednesday, Feb 23, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 18 Feb '22

18 Feb '22

IFISC Seminar on Wednesday Feb 23, 2022 at 14:30 Place: IFISC Seminar Room Title: Excursions through network theory Speaker: Ernesto Estrada, IFISC Abstract: I will give a panoramic view of some of my research topics which are currently active. These include: (1) the study of communicability functions on networks and their Euclidean geometric embedding; (2) the study of time-and-space nonlocal hops in networks and the emergence of sub- and superdiffusion; (3) the study of degree-biased Laplacians on networks and the emergence of advective-diffusive processes; (4) fractional calculus approaches to network theory. These topics will then be developed in details in a series of IFISC talks to be announced. Url event:https://ifisc.uib-csic.es/en/events/seminars/excursions-through-network-theory/

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Talk on Tuesday, Feb 22, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 17 Feb '22

17 Feb '22

Talk on Tuesday Feb 22, 2022 at 14:30 Place: Zoom Seminar Title: How can the structure of ecosystems predict species' survival? Speaker: Violeta Calleja Solanas, IFISC (CSIC-UIB) Abstract: Abstract: Understanding the characteristics that promote ecosystems&rsquo; resilience is crucial to explain and protect biodiversity. In this picture, environmental changes may alter species interactions, leading to cascade extinctions. For this reason, determining which species are more prone to initiate cascades is of paramount importance. Here, we study the structural features of ecological networks that better predict species&rsquo; survival when the strength of their interactions is varied. Employing the replicator equation as a proxy for species dynamics, we find that a high eigenvector centrality is a key factor for survival in mutualistic networks. This result reinforces the importance of the species&rsquo; neighbors identity and th e existence of positive feedback that prevent ecosystem collapse. This panorama changes with competitive interactions. In that case, the species that go extinct by extinctions cascades are determined not by their low eigenvector centrality but by a high degree. When both competitive and mutualistic interactions are considered, the behavior of the system is richer. Under those circumstances, not only networks are more resilient but eigenvector centrality and degree alone cannot fully predict species fate. Other individual properties such as the ratio between mutualistic and competitive interactions also play a fundamental role. Zoom link:&nbsp;&nbsp; https://us02web.zoom.us/j/87316222390?pwd=RG1qSG14TVA4aVBwNFBhRXAxNExWQT09&… Url event:https://ifisc.uib-csic.es/en/events/seminars/how-can-the-structure-of-ecosystems-predict-specie/

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Reminder: IFISC Seminar, TODAY - Wednesday, Feb 16, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 16 Feb '22

16 Feb '22

IFISC Seminar on Wednesday Feb 16, 2022 at 14:30 Place: IFISC Seminar Room Title: Floquet topological metal, avoiding the Anderson localization Speaker: Kun Woo Kim, Chung-Ang University, South Korea Abstract: We propose dynamical protocols allowing the realization of topological surface states in isolation. Our approach builds on the concept of synthetic dimensions eﬀectively generated by driving systems of given physical dimension with incommensurate frequencies. As a concrete example, we ﬁrst consider three-dimensional topological surface states of a four-dimensional quantum Hall insulator via a (1+2)-dimensional protocol. We present ﬁrst principle analytical calculations demonstrating that the engineered Floquet systems lie in the universality class of the corresponding topological insulator surface phases, the diﬀerence being that the latter require a supporting bulk, while the former do not. We back the analytical approach by numerical simulations and present a detailed blueprint for the realization of the synthetic surface phase with existing quantum linear optical network device technology. We then discuss generalizations, including a proposal for a quantum simulator of the two-dimensional surface states of a three-dimensional spin quantum Hall insulator in (1+1) dimensions. The seminar will be in hybrid format -- presential in the seminar room, but also online on Zoom: <a href="https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09">https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09</a> Url event:https://ifisc.uib-csic.es/en/events/seminars/floquet-topological-metal-avoiding-the-anderson-lo/

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Reminder: Talk, TODAY - Tuesday, Feb 15, 2022 at 11:00
by semfis＠ifisc.uib-csic.es 15 Feb '22

15 Feb '22

Talk on Tuesday Feb 15, 2022 at 11:00 Place: Zoom Seminar Title: An improved estimator of Shannon entropy with applications to systems with memory Speaker: Juan de Gregorio, IFISC (UIB-CSIC) Abstract: Many systems can be described with Markovian models in which the future state of the system only depends on its present state. While in some cases this is enough to predict the evolution of the system, in other cases it is necessary to take into account also the past states of the system. Which is the minimum number of past states needed in order to faithfully predict the future state of the system? It turns out that a simple answer to this question can be found from an analysis of Shannon entropy. Much work has been devoted in the past to obtain an accurate estimator of Shannon entropy for data coming from small samples. In this talk I will present an entropy estimator that takes into account time correlations and is particular useful to study systems with memory. As an example I will apply this method to the determination of the minimum memory required to describe lexical statistics of texts in different languages and daily precipitations in different worldwide locatio ns. Hybrid format: seminar room and Zoom link below. https://uibuniversitat.zoom.us/j/82040031215 Url event:https://ifisc.uib-csic.es/en/events/seminars/an-improved-estimator-of-shannon-entropy-with-appl/

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Talk on Tuesday, Feb 15, 2022 at 11:00
by semfis＠ifisc.uib-csic.es 11 Feb '22

11 Feb '22

Talk on Tuesday Feb 15, 2022 at 11:00 Place: Zoom Seminar Title: An improved estimator of Shannon entropy with applications to systems with memory Speaker: Juan de Gregorio, IFISC (UIB-CSIC) Abstract: Many systems can be described with Markovian models in which the future state of the system only depends on its present state. While in some cases this is enough to predict the evolution of the system, in other cases it is necessary to take into account also the past states of the system. Which is the minimum number of past states needed in order to faithfully predict the future state of the system? It turns out that a simple answer to this question can be found from an analysis of Shannon entropy. Much work has been devoted in the past to obtain an accurate estimator of Shannon entropy for data coming from small samples. In this talk I will present an entropy estimator that takes into account time correlations and is particular useful to study systems with memory. As an example I will apply this method to the determination of the minimum memory required to describe lexical statistics of texts in different languages and daily precipitations in different worldwide locatio ns. Hybrid format: seminar room and Zoom link below. https://uibuniversitat.zoom.us/j/82040031215 Url event:https://ifisc.uib-csic.es/en/events/seminars/an-improved-estimator-of-shannon-entropy-with-appl/

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IFISC Seminar on Wednesday, Feb 16, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 11 Feb '22

11 Feb '22

IFISC Seminar on Wednesday Feb 16, 2022 at 14:30 Place: IFISC Seminar Room Title: Floquet topological metal, avoiding the Anderson localization Speaker: Kun Woo Kim, Chung-Ang University, South Korea Abstract: We propose dynamical protocols allowing the realization of topological surface states in isolation. Our approach builds on the concept of synthetic dimensions eﬀectively generated by driving systems of given physical dimension with incommensurate frequencies. As a concrete example, we ﬁrst consider three-dimensional topological surface states of a four-dimensional quantum Hall insulator via a (1+2)-dimensional protocol. We present ﬁrst principle analytical calculations demonstrating that the engineered Floquet systems lie in the universality class of the corresponding topological insulator surface phases, the diﬀerence being that the latter require a supporting bulk, while the former do not. We back the analytical approach by numerical simulations and present a detailed blueprint for the realization of the synthetic surface phase with existing quantum linear optical network device technology. We then discuss generalizations, including a proposal for a quantum simulator of the two-dimensional surface states of a three-dimensional spin quantum Hall insulator in (1+1) dimensions. The seminar will be in hybrid format -- presential in the seminar room, but also online on Zoom: <a href="https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09">https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09</a> Url event:https://ifisc.uib-csic.es/en/events/seminars/floquet-topological-metal-avoiding-the-anderson-lo/

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