Found at least 20 result(s)
journal club Reehorst Marten (KCL)
at: 01:00 - 01:00 KCL, Strand room: Norfolk Building 342N abstract: | Keywords: |
regular seminar Zsuzsanna Baran (Cambridge)
at: 01:00 - 01:00 KCL, Strand room: S0.12 abstract: | It is well-known that a random walk on a (connected, finite, non-bipartite) graph converges to its invariant distribution. For some graphs it has been observed that this convergence happens rather abruptly. This phenomenon is called cutoff, and it has been established widely, but in general there is little understanding for what causes it.
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Regular Seminar Curt von Keyserlingk (King's College London)
at: 01:00 - 01:00 KCL Strand room: S0.12 abstract: | Keywords: |
Regular Seminar Curt von Keyserlingk (King's College London)
at: 01:00 - 01:00 KCL Strand room: S0.12 abstract: | In recent years we've greatly expanded our understanding of entanglement in many-body quantum systems; both how it behaves in ground states, and how it grows out-of-equilibrium. While entanglement is very difficult to measure in experiments, it has nevertheless driven progress in 1) the classification of quantum phases of matter and 2) strategies for efficiently simulating many-body systems on classical and quantum computers. I will review some recent progress in these directions. Along the way I will summarise some older results on how entanglement grows in many-body systems, briefly highlight some connections to holography, and present a conjecture about the asymptotic computational difficulty of calculating transport in many-body systems. Keywords: |
regular seminar Amos Chan (Lancaster University)
at: 01:00 - 01:00 KCL, Strand room: S4.23 abstract: | Quantum chaotic systems display correlation between eigenvalues as described by the random matrix theory (RMT). I will present three results on the universal aspects of many-body quantum chaos that go beyond the standard RMT paradigm. Firstly, I will present an exact scaling form of the spectral form factor (SFF) in a generic many-body quantum chaotic system, deriving the so-called "bump-ramp-plateau" behaviour. Secondly, I will introduce and provide an analytical solution of a generalization of SFF for non-Hermitian matrices, called Dissipative SFF, which displays a "ramp-plateau" behaviour with a quadratic ramp. Thirdly, I will provide evidences that non-Hermitian Ginibre ensemble behaviour surprisingly emerge in generic many-body quantum chaotic systems, due to the presence of many-body interaction. Keywords: |
regular seminar Cheuk Yu Mak (University of Southampton)
at: 01:00 - 01:00 KCL, Strand room: S4.29 abstract: |
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regular seminar Jan van Neerven (Delft University of Technology)
at: 01:00 - 01:00 KCL, Strand room: S4.29 abstract: | Keywords: |
colloquium Vincent Boucher (B12 Consulting)
at: 01:00 - 01:00 KCL, Strand room: Great Hall abstract: | After a PhD in cosmology, Vincent co-founded B12 Consulting with two other physicists. This company specializes in developing custom AI solutions, tailored for various business and organizational needs. The team now comprises over 40 individuals, primarily from science backgrounds including mathematics, physics, and engineering, with half holding PhDs. This diverse expertise fuels innovative approaches and solutions in their projects. In this presentation, Vincent will discuss his personal journey to becoming an entrepreneur, focusing on the challenges of bridging academic research with the world of business.
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regular seminar Tengyao Wang (London School of Economics and Political Science)
at: 01:00 - 01:00 KCL, Strand room: S5.20 abstract: | We propose a new method for changepoint estimation in partially-observed, high-dimensional time series that undergo a simultaneous change in mean in a sparse subset of coordinates. Our first methodological contribution is to introduce a 'MissCUSUM' transformation (a generalisation of the popular Cumulative Sum statistics), that captures the interaction between the signal strength and the level of missingness in each coordinate. In order to borrow strength across the coordinates, we propose to project these MissCUSUM statistics along a direction found as the solution to a penalised optimisation problem tailored to the specific sparsity structure. The changepoint can then be estimated as the location of the peak of the absolute value of the projected univariate series. In a model that allows different missingness probabilities in different component series, we identify that the key interaction between the missingness and the signal is a weighted sum of squares of the signal change in each coordinate, with weights given by the observation probabilities. More specifically, we prove that the angle between the estimated and oracle projection directions, as well as the changepoint location error, are controlled with high probability by the sum of two terms, both involving this weighted sum of squares, and representing the error incurred due to noise and the error due to missingness respectively. A lower bound confirms that our changepoint estimator, which we call 'MissInspect', is optimal up to a logarithmic factor. The striking effectiveness of the MissInspect methodology is further demonstrated both on simulated data, and on an oceanographic data set covering the Neogene period.
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regular seminar Jared White (KCL)
at: 01:00 - 01:00 KCL, Strand room: S5.20 abstract: | Many important examples of Banach algebras are also dual Banach spaces, and over the last thirty years a theory of so-called dual Banach algebras has emerged. An interesting and important way to study a dual Banach algebra is by studying (or even classifying) its weak*-closed (left/right/two-sided) ideals. It also turns out that weak*-closed ideals have connections to other topics as well, such as asymptotic properties of group representations.
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colloquium Giorgio Parisi (La Sapienza (Rome))
at: 01:00 - 01:00 KCL, Strand room: Anatomy Lecture Theatre: K6.29 abstract: | I will study the property of Chaos with Magnetic Field in spin glasses. I will report the results for Spin Glasses on Random Regular Graphs and 4D lattices. I will compare the simulation with analytic predictions obtained generating random trees according to the Replica Symmetry Breaking theory. I will show that using the Overalp Probability function P(q) as input one can quantitatively predict the degree of decorrelation as the field increases. One can also compute the finite volume effects in the magnetization and the susceptibility as a function of the field. Keywords: statistical physics |
regular seminar Peter Pang (University of Oslo)
at: 01:00 - 01:00 KCL, Strand room: S4.29 abstract: | The convergence of stochastic integrals driven by a sequence of Wiener processes $W_n\to W$ (with convergence in $C_t$) is crucial in the analysis of SPDEs. In this talk I shall focus on convergence of stochastic integrals of the form $\int_0^T V_n\, {\rm d} W_n \to \int_0^T V\,{\rm d} W$. Standard methods do not directly apply when $V_n$ converges to $V$ only weakly in the temporal variable. I shall discuss several convergence results that address the need to take limits of stochastic integrals when strong temporal convergence is absent. The key ingredient is an additional condition in the form of a uniform $L^1$ time translation estimate that is often available in SPDE settings but in itself insufficient to imply strong temporal compactness. This discussion will be in the context of applications to semilinear stochastic transport equations and stochastic conservation laws. Keywords: Convergence of Stochastic Integrals, SPDE |
Exceptional Seminar Meng-Chwan Tan (Singapore Natl. U.)
at: 01:00 - 01:00 KCL Strand room: K0.16 abstract: | This talk is about our latest work in [arXiv:2311.18302]. We shall show how one can define novel gauge-theoretic Floer homologies of four, three and two-manifolds that are associated with Vafa-Witten, Hitchin and complexified BF configurations, respectively, from the physics of a certain topologically-twisted 5d N=2 gauge theory. Via topological invariance and a 5d S-duality, we shall derive novel Atiyah-Floer correspondences of these gauge-theoretic Floer homologies which relate them to symplectic intersection Floer homologies of Higgs bundles, and a web of relations involving their loop/toroidal group generalizations and their Langlands dual. Lastly, through a soliton string theory interpretation of the 5d theory, we shall derive a Fukaya-Seidel type A-infinity category of Hitchin configurations on three-manifolds and its Atiyah-Floer correspondence. We therefore furnish purely physical realizations and generalizations of the mathematical conjectures and constructions of Haydys [1], Wang [2] and Abouzaid-Manolescu [3], and more. Keywords: |
colloquium Henri Darmon (McGill)
at: 01:00 - 01:00 KCL, Strand room: K6.29 (Anatomy Lecture Theatre) abstract: | Two of the most striking discoveries of 18th and 19th century number theory are the Kronecker-Weber theorem and the theory of complex multiplication. The first asserts that the maximal abelian extension of the field Q of rational numbers is generated by roots of unity in other words, that all abelian extensions of Q can be constructed by adjoining values at rational arguments of the transcendental function
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Regular Seminar De-liang Zhong (Imperial College, London)
at: 01:00 - 01:00 KCL Strand room: S0.12 abstract: | We study Chern-Simons theories at large N with either bosonic or fermionic matter in the fundamental representation. We will show that for smooth conformal line operators, their spectrum and shape dependence can be effectively bootstrapped using minimal inputs. Keywords: |
at: 01:00 - 01:00 KCL, Strand room: K2.31 (Nash Lecture Theatre) abstract: | Keywords: Internal Physics/Maths event, joint celebration of our research. |
regular seminar Nik Nsken (King's College London)
at: 01:00 - 01:00 KCL, Strand room: S4.29 abstract: | This talk will trace the development of computational statistics (and machine learning) from the inception of Markov Chain Monte Carlo in the 1940s at Los Alamos to the current advances in generative AI (see, e.g. https://deepai.org/machine-learning-model/text2img). The story is closely connected to the analysis of diffusion processes, and we will see interactions with neighbouring fields such as PDEs, stochastic analysis and geometry. Keywords: Computational statistics, diffusion processes, machine learning, generative AIn/a |
regular seminar Chrysoula Markou ()
at: 01:00 - 01:00 KCL, Strand room: K0.20 abstract: | We propose a covariant technique to excavate physical bosonic string states by entire trajectories rather than individually. The approach is based on Howe duality: the strings spacetime
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journal club Joseph Smith (KCL)
at: 01:00 - 01:00 KCL, Strand room: Norfolk 342N abstract: | Keywords: |
regular seminar Joseph Smith (KCL)
at: 01:00 - 01:00 KCL, Strand room: Norfolk342N abstract: | Keywords: |