Department of Mathematics and Computer Science

Speaker: Ben Brown (​IBM).Abstract: As a warmup for my seminar ‘Quantum computing with anyons is fault tolerant’, I will give a board talk about decoding algorithms for topological stabiliser codes. If there is time, I will briefly cover decoding for a non-Abelian anyon model.The material I will cover is reviewed here https://ieeexplore.ieee.org/abstract/document/10048521.I hope to also review the non-Abelian Clifford stabiliser code in section III in the following paper https://journals.aps.org/prx/abstract/10.1103/vrty-qs5h.

Speaker: Ben Brown (​IBM).Abstract:In seminal work (arXiv:quant-ph/9707021) Alexei Kitaev proposed topological quantum computing (arXiv:cond-mat/0010440, arXiv:quant-ph/9707021, arXiv:quant-ph/0001108, arXiv:0707.1889), whereby logic gates of a quantum computer are conducted by creating, braiding and fusing anyonic particles on a two-dimensional plane. Furthermore, he showed the proposal is inherently robust to local perturbations (arXiv:cond-mat/0010440, arXiv:quant-ph/9707021, arXiv:1001.0344, arXiv:1001.4363) when anyons are created as quasiparticle excitations of a topologically ordered lattice model prepared at zero temperature. Over the decades following this proposal there have been considerable technological developments towards the construction of a fault-tolerant quantum computer. Rather than maintaining some target ground state at zero temperature, a modern approach is to actively correct the errors a target state experiences, where we use noisy quantum circuit elements to identify and subsequently correct for deviations from the ideal state. We present an error-correction scheme that enables us to carry out robust universal quantum computation by braiding anyons. We show that our scheme can be carried out on a suitably large device with an arbitrarily small failure rate assuming circuit elements are below some threshold level of local noise. The error-corrected scheme we have developed therefore enables us to carry out fault-tolerant topological quantum computation using modern quantum hardware that is now under development.

Shomrik Bhattacharya defends his PhD thesis at a public lecture: “The Fundamental Group of the Complement of the Wobbly Divisor in the Intersection of Two Quadrics”.The chairman of the assessment committee, Associate Professor Fabian Haiden, will act as chairman at the defence.The PhD defence takes place in IMADA Conference Room (Ø18-509-2).All are welcome.

Yuki Matsubara defends his PhD thesis at a public lecture: “A Study of Moduli Spaces of Parabolic Connections and Geometric Langlands Correspondence”.The chairman of the assessment committee, Associate Professor Fabian Haiden, will act as chairman at the defence.The PhD defence takes place in U146 (Ø15-501a-2).All are welcome.

Jonas Vistrup defends his PhD thesis at a public lecture: “Explainable AI and the Law: Expert Systems for Danish Traffic Law”.The chairman of the assessment committee, Associate Professor Tariq Yousef, will act as chairman at the defence.The PhD defence takes place in U48A (Ø4-602-2).All are welcome.

Poster Session and presentation

Want to know what is going on behind the scenes at IMADA?Come and join us for 2 x 20 min. inspiring talks while you enjoy a free “casual after-work” beer with your fellow student, colleague or teacher.This time Postdoc Xueying Qin (Topic: Using LLMs in Lean 4: The Next Stage of Proof Automation) and Associate Professor Lars Rohwedder (Topic: AI for Math and TCS Research: A User's Perspective) will each spend 20 minutes each telling you about their current research.

Speaker: Pallav Goyal (​University of Southern Denmark).Abstract: TBA

Speaker: Shing Tak Lam (​University of Warwick).Abstract: TBA

Students develop a wide range of competences throughout their education, but they do not always recognise everything they become better at along the way.