NumPI

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Seminar on Quantum Computing: Andrew Daley (University of Oxford, UK) Monday 23/09/2024
by Gianna M. Del Corso 18 Sep '24

18 Sep '24

Dear All, As part of the CN1-SPOKE 10 on Quantum Computing, this year too we plan to organize a weekly seminar series. The first event this year is a talk proposed by by Marilu Chiofalo and Jorge Yago Malo. Title: Analogue and digital quantum simulation: state of the art and opportunities Speaker: Andrew Daley (University of Oxford, UK) Venue: Sala Galilei (room 131, Bldg. C, Department of Physics) Time: Monday, 23/09/2024, 15:00 Abstract: There has been impressive recent progress in developing highly controlled quantum systems, ranging from superconducting qubits to neutral atoms in tweezer arrays. These systems provide a route to medium-scale quantum computing, but also the possibility to build and study models of many-body systems. These range from electrons in solid state physics and materials across to toy models for information spreading in black holes (made possible by long-range interactions). This impressive progress had led to new opportunities for studying basic science, but has also opened pathways towards making quantum simulation useful in solving problems from chemistry, materials and wider fields. I will give an introduction to the state of the art in these systems, illustrated with our recent theoretical work on fast scrambling of quantum information in systems with long-range interactions. I will also discuss the opportunities and challenges associated with important questions, including (1) To which degree can analogue devices be quantitatively reliable? And (2) when can we use these systems to give us access to useful information that we cannot compute with conventional supercomputers? Everyone is welcome! @@@@@@@@@@@@@@@@@ Gianna M. Del Corso, PhD Dipartimento di Informatica, Università di Pisa Largo Pontecorvo, 3 56127 Pisa, Italy ph. +39-050-2213118 @@@@@@@@@@@@@@@@@

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Upcoming workshop: NumPI day
by Stefano Massei 18 Sep '24

18 Sep '24

Dear all, I am glad to announce to you that Monday 23rd September we will have a one-day workshop of numerical analysis titled NumPI day. Anyone interested is welcome! The event will take place from 9 a.m. to 16 p.m. in the Aula Magna of the department of Mathematics, see the attached schedule. Best regards, Stefano

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[Indico] Dr Maria Strazzullo, Nonlinear Feedback Control via Dynamical Low-Rank Approximation, 09/09/2024, 15:30 Europe/Rome
by noreply＠cs.dm.unipi.it 09 Sep '24

09 Sep '24

Title: Nonlinear Feedback Control via Dynamical Low-Rank Approximation, Speaker(s): Dr Maria Strazzullo, Politecnico di Torino, Date and time: 9 Sept 2024, 15:30 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento Di Matematica (Sala Riunioni). You can access the full event here: https://events.dm.unipi.it/e/288 Abstract -------- Feedback control plays a crucial role in optimizing the performance of dynamical systems by minimizing a predefined cost functional, to stabilize the system towards a desired state. Despite its undeniable effectiveness, the applicability of feedback control is often limited by the high dimensionality of state spaces, a challenge that is even more pronounced in parametric settings. To overcome these limitations, we employ the Dynamical Low-Rank Approximation (DLRA) methodology, which offers an efficient and accurate solution to high-dimensional feedback control problems. Our approach significantly accelerates the solution of State-Dependent Riccati Equations (SDREs) for infinite horizon optimal control by providing a compact, low-dimensional representation of the system that evolves dynamically with respect to the problem. This not only enhances accuracy but also provides effective real-time control, solving several parametric instances simultaneously. To further accelerate the solution of the SDREs, we propose cascade-control (cc-) algorithms that leverage the Riccati solution from a previous parameter to improve the convergence of Newton-based methods applied to SDREs. The robustness and efficiency of our algorithms are validated through nonlinear test cases. Comparative analysis demonstrates that the proposed ccDLRA outperforms global Proper Orthogonal Decomposition model order reduction (ccPOD), offering superior speed and accuracy when compared to the full-order model (ccFOM) solution. Note ---- Reminder for this afternoon's seminar. -- Indico :: Email Notifier https://events.dm.unipi.it/e/288

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[Indico] Dr Maria Strazzullo, Nonlinear Feedback Control via Dynamical Low-Rank Approximation, 09/09/2024, 15:30 Europe/Rome
by fabio.durastante＠unipi.it 05 Sep '24

05 Sep '24

Title: Nonlinear Feedback Control via Dynamical Low-Rank Approximation, Speaker(s): Dr Maria Strazzullo, Politecnico di Torino, Date and time: 9 Sept 2024, 15:30 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento Di Matematica (Sala Riunioni). You can access the full event here: https://events.dm.unipi.it/e/288 Abstract -------- Feedback control plays a crucial role in optimizing the performance of dynamical systems by minimizing a predefined cost functional, to stabilize the system towards a desired state. Despite its undeniable effectiveness, the applicability of feedback control is often limited by the high dimensionality of state spaces, a challenge that is even more pronounced in parametric settings. To overcome these limitations, we employ the Dynamical Low-Rank Approximation (DLRA) methodology, which offers an efficient and accurate solution to high-dimensional feedback control problems. Our approach significantly accelerates the solution of State-Dependent Riccati Equations (SDREs) for infinite horizon optimal control by providing a compact, low-dimensional representation of the system that evolves dynamically with respect to the problem. This not only enhances accuracy but also provides effective real-time control, solving several parametric instances simultaneously. To further accelerate the solution of the SDREs, we propose cascade-control (cc-) algorithms that leverage the Riccati solution from a previous parameter to improve the convergence of Newton-based methods applied to SDREs. The robustness and efficiency of our algorithms are validated through nonlinear test cases. Comparative analysis demonstrates that the proposed ccDLRA outperforms global Proper Orthogonal Decomposition model order reduction (ccPOD), offering superior speed and accuracy when compared to the full-order model (ccFOM) solution. -- Indico :: Email Notifier https://events.dm.unipi.it/e/288

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Seminario a Settembre
by Luca SALUZZI 03 Aug '24

03 Aug '24

Cari tutti, vi mando questa email perche' a Settembre, la settimana del 9-13, verra' in visita Maria Strazzullo dal Politecnico di Torino e vorrei organizzare un suo seminario. Si pensava di farlo o Lunedì 9 o Martedi' 10. Voi avete preferenze su data e orario? Così da permettere di massimizzare il numero di partecipanti. Intanto buone vacanze e ci si vede a Settembre!! Ciao, Luca

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23/07/2024 — R. Van Beeumen — Seminari CN1-SPOKE 10 (Quantum Computing)
by Gianna M. Del Corso 23 Jul '24

23 Jul '24

Dear all, This is a reminder for today’s seminar on quantum computing. Title: Hybrid Quantum-Classical Krylov Methods for Eigenvalue Computation Speaker: Roel Van Beeumen (Lawrence Berkeley National Laboratory) Venue: Sala Gerace, Dipartimento di Informatica Time: Tuesday, 23/07/2024, 14:30 Below the link for the online attendance. https://teams.microsoft.com/l/meetup-join/19%3ameeting_MjliOWRmMDAtMjA4ZC00… Everyone is welcome to attend! Gianna @@@@@@@@@@@@@@@@@ Gianna M. Del Corso, PhD Dipartimento di Informatica, Università di Pisa Largo Pontecorvo, 3 56127 Pisa, Italy ph. +39-050-2213118 @@@@@@@@@@@@@@@@@

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Seminar on Quantum Computing: Roel Van Beeumen Tuesday 23/7, 14:30
by Gianna M. Del Corso 16 Jul '24

16 Jul '24

Dear All, As part of the CN1-SPOKE 10 on Quantum Computing, we are pleased to announce the last seminar before the summer break. Title: Hybrid Quantum-Classical Krylov Methods for Eigenvalue Computation Speaker: Roel Van Beeumen (Lawrence Berkeley National Laboratory) Venue: Sala Gerace, Dipartimento di Informatica Time: Tuesday, 23/07/2024, 14:30 Abstract: Classical algorithms based on Krylov subspaces are among the most successful tools in the field of numerical linear algebra. More recently, the emergence of quantum subspace methods has resulted in a promising class of hybrid quantum-classical algorithms for eigenvalue approximation, e.g., in the fields of condensed matter physics and electronic structure theory. These quantum Krylov methods harness quantum computers to generate the subspace basis states and retrieve the projected problem through quantum measurement. However, the classical computation of the Ritz values often poses challenges due to the ill-conditioning of the associated generalized eigenvalue problem. In this talk, we present an overview of quantum subspace algorithms from a numerical linear algebra perspective. We discuss strategies to avoid solving an ill-conditioned eigenvalue problem, explain their implementation on quantum computers, and provide numerical and theoretical evidence of their convergence. Furthermore, we present strategies to improve the robustness, especially in the presence of noise. Everyone is welcome to attend! Gianna @@@@@@@@@@@@@@@@@ Gianna M. Del Corso, PhD Dipartimento di Informatica, Università di Pisa Largo Pontecorvo, 3 56127 Pisa, Italy ph. +39-050-2213118 @@@@@@@@@@@@@@@@@

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[Indico] Dr Jie Meng, Theoretical and computational properties of quasi-Toeplitz M-matrices, 15/07/2024, 15:00 Europe/Rome
by fabio.durastante＠unipi.it 14 Jul '24

14 Jul '24

Title: Theoretical and computational properties of quasi-Toeplitz M-matrices, Speaker(s): Dr Jie Meng, Ocean University of China, Date and time: 15 Jul 2024, 15:00 (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Sala Riunioni). You can access the full event here: https://events.dm.unipi.it/e/287 Abstract -------- A quasi-Toeplitz matrix is a semi-infinite matrix of the form $A=T(a)+E$, where $T(a)$ is a Toeplitz matrix with entries $(T(a))_{i,j}=a_{j-i}$, for $a_{j-i}\in\mathbb C$, $i,j\ge 1$ and $E$ is a compact correction. Quasi-Toeplitz $M$-matrices are encountered in the study of quadratic matrix equations arising in the analysis of a 2-dimensional Quasi-Birth-Death (QBD) stochastic process. We investigate the properties of such matrices and provide conditions under which a quasi-Toeplitz matrix is an $M$-matrix. We show that under a mild and easy-to-check condition, an invertible quasi-Toeplitz $M$-matrix has a unique square root that is an $M$-matrix possessing quasi-Toeplitz structure. Some issues concerning the computation of the square root of quasi-Toeplitz $M$-matrices are discussed and numerical experiments are performed -- Indico :: Email Notifier https://events.dm.unipi.it/e/287

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Difesa dottorato
by Angelo Alberto CASULLI 12 Jul '24

12 Jul '24

Cari tutti, Lunedì 22 luglio alle 14.30 discuterò la mia tesi di dottorato dal titolo "Block rational Krylov methods for matrix equations and matrix functions" presso la Scuola Normale. Chiunque abbia piacere di partecipare è il benvenuto! Seguirà un piccolo rinfresco nel chiostro della Scuola. A presto, Angelo Casulli

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[Indico] Dr Jie Meng, Theoretical and computational properties of quasi-Toeplitz M-matrices, 7/15/24, 3:00 PM Europe/Rome
by fabio.durastante＠unipi.it 04 Jul '24

04 Jul '24

Title: Theoretical and computational properties of quasi-Toeplitz M-matrices, Speaker(s): Dr Jie Meng, Ocean University of China, Date and time: Jul 15, 2024, 3:00 PM (Europe/Rome), Lecture series: Seminar on Numerical Analysis, Venue: Dipartimento di Matematica (Sala Riunioni). You can access the full event here: https://events.dm.unipi.it/e/287 Abstract -------- A quasi-Toeplitz matrix is a semi-infinite matrix of the form $A=T(a)+E$, where $T(a)$ is a Toeplitz matrix with entries $(T(a))_{i,j}=a_{j-i}$, for $a_{j-i}\in\mathbb C$, $i,j\ge 1$ and $E$ is a compact correction. Quasi-Toeplitz $M$-matrices are encountered in the study of quadratic matrix equations arising in the analysis of a 2-dimensional Quasi-Birth-Death (QBD) stochastic process. We investigate the properties of such matrices and provide conditions under which a quasi-Toeplitz matrix is an $M$-matrix. We show that under a mild and easy-to-check condition, an invertible quasi-Toeplitz $M$-matrix has a unique square root that is an $M$-matrix possessing quasi-Toeplitz structure. Some issues concerning the computation of the square root of quasi-Toeplitz $M$-matrices are discussed and numerical experiments are performed -- Indico :: Email Notifier https://events.dm.unipi.it/e/287

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