The classification of the symplectic fillings of a given contact 3-manifold poses an interesting problem. It is motivated by results that demonstrate that the symplectic fillings of a contact 3-manifold hold information on the contact structure. Most notably, the contact structure of any contact 3-manifold that admits a strong symplectic filling is tight. Although the symplectic fillings of certain contact manifolds have been classified, the general classification remains an open problem. Working towards this, one can consider the geography problem for symplectic fillings. In the paper Spine removal surgery and the geography of symplectic fillings, Sam Lisi and Chris Wendl prove the existence of a universal bound for the geography (Euler characteristic and signature) of possible minimal strong symplectic fillings of a closed contact 3-manifold with a supporting planar spinal open book decomposition. Following a brief introduction to symplectic and contact topology, the aim of my talk is to explain Lisi and Wendl's result. For this purpose, I will provide an overview of symplectic fillings and the related geography problem, and introduce spinal open book decompositions.
\r\n
\r\n
The classification of gait patterns is an important challenge in movement analysis, as it supports clinical assessment and decision-making by enabling diagnosis and severity stratification. In this talk, I will discuss the potential of Topological Data Analysis (TDA) for gait pattern classification. Unlike conventional approaches that rely on explicit detection of Gait Events (GEs) to compute Spatiotemporal Gait Parameters (SGPs), TDA characterises the global structure of gait signals directly, capturing relationships and patterns in the data without requiring GEs. This is particularly relevant in real-world settings, where GE detection can be diQicult due to heterogeneity in walking conditions and gait patterns, potentially biasing clinically relevant metrics and, consequently, decision-making.
\r\nWithin our department, preliminary results have shown that TDA-based features can achieve classification performance comparable to that of SGPs in fall-risk assessment. These findings suggest that topology oQers a competitive alternative for representing gait data, with the potential to better handle variability across subjects and pathological
\r\nconditions.
\r\nBuilding on these results, we plan to further extend the TDA framework in two directions. First, we aim to investigate time-aware topological methods to better capture the
\r\ntemporal structure of gait signals. Second, we will explore Topological Deep Learning (TDL) approaches to reduce reliance on handcrafted design choices and potentially
\r\nimprove classification performance. By combining the robustness of topology with datadriven representation learning, this work seeks to provide robust tools for the classification of typical and pathological gait patterns.
\r\n
The ultrafast motion of electrons is a frontier problem for photochemical processes, as electron motion is a key ingredient of all chemical reactions. Electronic rearrangement is also the means by which light energy is harnessed in photochemistry. The timescale for coherent electron dynamics is set by the energetic splitting of the electronic states, which in small molecular systems, is on the scale of an electron volt (eV). This sets the natural timescale for electronic motion to be few-to-sub femtosecond (fs).
\r\n
\r\nTo approach these extreme timescales, we can use short pulses of light to excite small quantum systems. For instance, the impulsive interactions between a light field and a quantum system can induce time-dependent oscillations in the charge density. Such electronic wavepacket motion (in the absence of nuclear motion) has come to be referred to as charge migration [1]. While the initial charge dynamics following impulsive excitation (or ionization) begins as purely electronic motion, this wavepacket will couple to other degrees of freedom in the system (i.e. nuclear motion or chemical dynamics) and lead to localization of the charge. The transfer of electronic charge across molecular bonds is fundamental to an understanding of charge transfer phenomena.
\r\n
\r\nThe study of these fundamental phenomena requires state-of-the-art light sources, such as the Linac Coherent Light Source (LCLS), an X-ray free electron laser (XFEL) facility which produces high-brightness, ultrashort pulses, with wavelength continuously tunable across the x-ray regime. Schemes to provide isolated, sub-femtosecond pulses from an FEL are being explored at facilities world-wide, and recently we have demonstrated such pulses at the LCLS [2]; opening the door for time-resolved measurements of ultrafast electron dynamics on their natural timescale. In my talk, I will highlight our recent developments in probing electronic motion in small molecular systems. We have employed sub-femtosecond pulses from the XFEL to study ultrafast charge dynamics in both core-excited [3,4,5] and low-lying cationic systems [6]. We are also developing nonlinear x-ray spectroscopies [7,8] to initiate and control electron dynamics. The control of coherent electron motion represents a significant step towards achieving charge-directed reactivity [9], a grand challenge for the field of attosecond science.
\r\n
\r\n[1] Cederbaum and Zobeley 1999 Chemical Physics Letters 307 205–210
\r\n[2] Duris and Li et al. 2020 Nature Photonics 14 30-36
\r\n[3] Li and Driver et al. 2022 Science 375 285-290
\r\n[4] Driver et al. 2024 Nature 632 762-767 (2024)
\r\n[5] Wang and Driver et al. Phys. Rev. X 15 011008 (2005)
\r\n[6] Driver et al. ArXiv:2411.01700
\r\n[7] O’Neal et al. 2020 Phys. Rev. Lett. 125 073203
\r\n[8] Biggs et al. 2023 Proc. Nat. Acad. Sci. 110 15597-15601
\r\n[9] F. Remacle, R. D. Levine, and M. A. Ratner 1998 Chem. Phys. Lett. 285, 25
\r\n
Please join us for the QSE Center Quantum Seminar with Robin Blume-Kohout from Sandia National Labs who will give the talk \"Assessing performance of logical operations with detector error models\" and Benoit Vermersch from Quobly and UGA who will give the talk \"Randomized measurements for large-scale quantum experiments\" on Friday April 24 from 11:30 to 13:30.
\r\nLocation: GR B3 30
\r\n
\r\n11:30-12:20 Benoit Vermersch
\r\n12:20-12:40: Pizza lunch
\r\n12:40-13:30: Robin Blume-Khout
\r\nAll PhDs, postdocs, students, group leaders, and PIs are welcome to join us.
\r\n
\r\nABSTRACT:
\r\n1. \"Assessing performance of logical operations with detector error models\" - Robin Blume-Kohout
\r\nQuantum computing is rapidly transitioning from the “NISQ” paradigm in which circuits and gates are executed directly on physical qubits to a fault tolerant “FTQC” paradigm in which circuits and gates are executed on encoded, error-corrected logical qubits. We want to model errors in gates. Logic gates on physical qubits are modeled by process matrices, derived from theory or estimated from tomography. But describing logical gates on logical qubits demands a richer model — specifically, detector error models — that can describe QEC syndrome data. I’ll introduce detector error models and summarize three recent papers in which we show how to estimate detector error models from data [https://arxiv.org/abs/2504.14643], how to simulate arbitrary small Markovian errors in Clifford circuits [https://arxiv.org/abs/2504.15128], and how to generate detector error models from arbitrary circuit-level Markovian errors [https://arxiv.org/abs/2603.18457].
\r\n
\r\n2. \"Randomized measurements for large-scale quantum experiments\" - Benoit Vermersch
\r\nThe randomized measurements toolbox is now routinely used in quantum experiments to estimate fundamental quantum properties, such as entanglement [1].
\r\nWhile experimentalists appreciate the simplicity and robustness aspects of such measurement protocols, a challenge for theorists is to design strategies for overcoming statistical errors using \"cheap\" polynomial resources in system size.
\r\nIn this context, I will present recent upgrades to the randomized measurements toolbox that address this challenge for large-scale quantum states that are relevant to the field of quantum simulation. In particular, I will discuss efficient protocols for measuring entanglement [2] and performing state tomography [3].
\r\n
\r\n[1] A. Elben, S. T. Flammia, H.-Y. Huang, R. Kueng, J. Preskill, B. Vermersch, and P. Zoller, The Randomized Measurement Toolbox, Nat Rev Phys 5, 9 (2022).
\r\n[2] B. Vermersch, M. Ljubotina, J. I. Cirac, P. Zoller, M. Serbyn, and L. Piroli, Many-Body Entropies and Entanglement from Polynomially Many Local Measurements, Phys. Rev. X 14, 031035 (2024).
\r\n[3] M. Votto, M. Ljubotina, C. Lancien, J. Ignacio Cirac, P. Zoller, M. Serbyn, L. Piroli, B. Vermersch, arXiv:2507.12550
\r\n
\r\nBIOS:
\r\nRobin Blume-Kohout was born on a kitchen table in the Alaska Bush almost (but not quite) 50 years ago. Unfortunately, things went downhill thereafter. He is now the founder and codirector of Sandia’s Quantum Performance Lab (QPL), where he and his fellow malcontents dream up new ways to assess and enhance the performance of quantum computers and their components.
\r\nBenoit Vermersch is an associate professor at the University of Grenoble Alpes, member of the LPMMC currently on leave in the quantum startup Quobly Research interests include implementations of quantum processing units with cold atoms, trapped ions, superconducting qubits; measurement protocols for entanglement-related quantities, out-of-time ordered correlators, topological invariants; many-body entanglement theory; quantum networks: Light-matter interfaces, quantum state transfer protocols, waveguide quantum electrodynamics; and tensor-network numerical methods: Matrix-Product-States and DMRG,TEBD related algorithms.
Hosted by Solange Denervaud, CIBM Flagship Project Officer, we are pleased to invite you to attend the CIBM Visitors Talk on April 24th at 13:00 CEST by Mary Helen Immordino-Yang from the University of Southern California who will be sharing on “Longitudinal neurodevelopmental correlates of mid-adolescents’ psychosocial processing: A path to young adult wellbeing?”.
\r\n
\r\nAbstract
\r\nCombining open-ended interviews (outside the scanner) with structural, trial-by-trial, and resting-state functional MRI neuroimaging, we examined real-time functional neural dynamics underlying diverse urban mid-adolescents’ cognitive and emotional engagement with compelling social stories at two time-points, two years apart. We found that the patterns of longitudinal change in neural network dynamics predicted psychosocial outcomes five years later in young adulthood.
\r\nWe found that “transcendent thinking” – seeing situations not just in terms of X happened to person A, which makes me feel thusly, but in terms of the larger societal and contextual forces that shaped how Person A was treated and how Person A reacted, the broader implications and lessons one can draw from that situation, and the larger issues it exemplifies or reveals—correlated with a particular set of neural activity dynamics and predicted future structural and functional neural development across the subsequent two years, controlling for the starting state of neural development, and independent of IQ and SES. Transcendent thinking also countered negative effects of exposure to community violence on structural brain development.
\r\nThe neural development predicted by transcendent thinking (the changes in the brain across the 2-year period) in turn predicted young adult identity strength, self-liking, relationship satisfaction, and achievement 5 years later.
\r\nThese findings reveal a novel predictor of neural development across mid-adolescence, and underscore the active role adolescents play in their own brain development through the meaning they make of the social world. Implications for secondary education and pedagogy will be discussed.
\r\n
\r\n
We present a novel necessary and sufficient principle for multiple testing methods controlling an expected loss. This principle asserts that every such multiple testing method is a special case of a general closed testing procedure based on e-values. It generalizes the Closure Principle, known to underlie all methods controlling familywise error and tail probabilities of false discovery proportions, to a large class of error rates -- in particular to the false discovery rate (FDR). By writing existing methods as special cases of this procedure, we can achieve uniform improvements, as we demonstrate for the e-Benjamini-Hochberg and the Benjamini-Yekutieli procedures, and the self-consistent method of Su (2018). We also show that methods derived using our novel e-Closure Principle generally control their error rate not just for one rejected set, but simultaneously over many, allowing post hoc flexibility for the researcher.
\r\nMoreover, we show that because all multiple testing methods for all error metrics are derived from the same procedure, researchers may even choose the error metric post hoc. Under certain conditions, this flexibility even extends to post hoc choice of the nominal error rate.
\r\n
\r\n
\r\n
Directeur de thèse : Prof. A. Züttel,
\r\nProgramme doctoral en Chimie et génie chimique
\r\nThèse n° 11688
\r\n
\r\nPour participer à la soutenance publique, merci de contacter directement l’intervenant
Thesis Directors: Prof. R. Gruetter, Dr A. Capozzi
\r\nPhysics doctoral program
\r\nThesis Nr. 11427
\r\n
\r\nTo take part in the public defense, please contact directly the speaker