The colloquium of the Centre for Mathematical Sciences, Lund University, normally runs once a month, Wednesdays from 14.00 until 15.00 in the Hörmander, Riesz or Gårding lecture halls. It is aimed at the entire Centre for Mathematical Sciences with overview talks by renowned experts about exciting mathematical topics. The purpose of our colloquium is twofold: firstly, it is to provide an inspiring overview of a specific field of mathematics, secondly, it is to bring together students and staff from the entire department and to serve as the proverbial waterhole where contacts are made and maintained. For more information, see the guidelines for colloquium speakers.

The colloquium is organized by Dragi Anevski, Magnus Goffeng, Magnus Oskarsson, Tony Stillfjord and Anitha Thillaisundaram. Feel free to contact any one of us for questions or suggestions for colloquia speakers. See also the information for suggesting colloquium speakers.

March 18 at MH:Gårding

Speaker

Matthias Christandl (Copenhagen)

Title

Fault-tolerant quantum computation

Abstract

The qubit quality of available quantum devices is increasing, yet it is expected that individual qubit operations (gates) will remain noisy for the foreseeable future. The execution of a sizeable quantum algorithms (e.g. factoring numbers, simulating materials), therefore requires a software solution to the noise problem. In essence, one needs to simulate a virtual noiseless quantum processor with a physical noisy quantum device. Is this possible at all? Yes, says a foundational result from the 90s (if the gate noise is below a threshold). I will start by giving some key ideas and intuition behind this result. 

In contrast to stand-alone single-core quantum computers, in many distributed scenarios (e.g. a multi-core quantum processor or the quantum internet) quantum processors need to pass qubits among each other, and have therefore quantum inputs, quantum outputs or even both. Just imagine the communication from one noisy quantum devices to another one via even noisier quantum communication channels. Also, such scenarios need to be secured against noise. It's possible - I will explain how ;-)

April 8 at MH:Hörmander

Speaker

Chloe Martindale (Bristol)

Title

Post-quantum cryptography

Abstract

Our modern life relies on cryptography for both privacy and security. In this talk we will talk about the progress of quantum computing and the timeline of the threat to our online privacy as well as the mathematical solutions to these problems.

April 22 at MH:Hörmander

Speaker

Tim Dokchitser (Bristol)

Title

Slicing surfaces

Abstract

We study a map of terrain by examining height lines, essentially slicing a surface representing the terrain horizontally into curves. These curves are typically smooth, but there are usually a few 'bad slices', even for a smooth surface. In geometry, number theory, and physics these bad slices turn out to be very interesting, as they capture a lot of information about the surface. They may be called degenerations, singular fibres, bad reduction, phase transitions, mixed structures or qualitative changes, depending on the context, and are often more informative than the good slices. I will discuss a classification of these bad slices in the context of algebraic geometry, and number theory. This is an intricate question, and I will outline some of the arithmetic, geometry and combinatorics involved in this classification.

May 13 at MH:Gårding

Speaker

Julie Rowlett (Chalmers and the University of Gothenburg)

Title

Isospectrality and Moduli Spaces

Abstract

Have you heard the question:  can one hear the shape of a drum?  Do you know the answer?  Mathematically, this question is an inverse spectral problem, or equivalently, a question about isospectrality.  Although I suspect that many people are familiar with this question and its answer, there are several related questions which remain unsolved.  In this talk, we will investigate inverse spectral problems and variations thereof in geometric moduli spaces consisting of certain types of `drums.’ 

May 27 at MH:Hörmander

Speaker

Erik Sandelin (FRA)

Title

Classified

Abstract

Classified

June 10 at MH:Hörmander

Speaker

Yingda Cheng (Virginia Tech)

Title

Kinetic equations and high-dimensional scientific computing

Abstract

In this talk, I will overview kinetic equations, which are fundamental models in mathematical physics. The understanding and numerical simulations of kinetic equations are critical for the understanding of nuclear fusion and many other important areas. 

Deterministic simulations of kinetic models are challenging due to the high dimensionality of the model. In the second part of the talk, I will give an overview of some efforts in high-dimensional scientific computing, touching upon techniques in sparse grid, low-rank and machine learning. Those techniques are essential in modern scientific computing to tackle curse of dimensions in challenging physic simulations of various kinds.