【时间】2026年9月22日（星期二） 10:00

【地点】量子院526报告厅

【主持】魏世杰副研究员  量子算法应用研发团队

【题目】Low-overhead fault-tolerant topological quantum memory

【摘要】Fault-tolerant quantum computation requires quantum memories that suppress logical errors with as few physical qubits as possible. The surface code is a leading architecture due to its locality and high threshold, but its resource overhead remains a major obstacle. In this talk, I will discuss a series of constructions of low-overhead topological quantum memories based on bivariate bicycle codes and their generalizations. The main idea is to combine the practical advantages of quantum low-density parity-check (qLDPC) codes with the physical structure of topological order. Using Laurent-polynomial and Gr?bner-basis methods, we can identify anyon excitations, compute logical dimensions, and optimize code layouts on twisted tori. I will then explain how the topological-order viewpoint leads to planar qLDPC codes with open boundaries, where boundary anyon condensation and lattice grafting preserve locality and code performance while substantially reducing qubit overhead. I will also discuss self-dual bivariate bicycle codes that support transversal Clifford gates, as well as subsystem bivariate bicycle codes that retain the high-rate BB logical structure while allowing local weight-4 gauge measurements.

【报告人简介】Yu-An Chen is an Assistant Professor at the International Center for Quantum Materials, Peking University. He earned dual B.S. degrees in Mathematics and Physics from the Massachusetts Institute of Technology in 2015 and a Ph.D. in Physics from the California Institute of Technology in 2020. He then worked as a research scientist on Google’s Quantum AI team and, from September 2020 to June 2023, was a Joint Quantum Institute Postdoctoral Fellow at the University of Maryland, College Park. Dr. Chen joined Peking University in July 2023. His research focuses on quantum error correction, topological phases of matter, and anomalies of generalized symmetries on lattices.