Title: [Joint CQSE & NCTS Seminar] Decoding of topological quantum codes
Speaker: Prof. Ching-Yi Lai (Assistant Professor, Department of Electronics and Electrical Engineering, National Yang Ming Chiao Tung University)
Date: Feb. 25, 2022, 14:30-15:30
Place: NCTS Physics Lecture Hall, 4F, Chee-Chun Leung Cosmology Hall, NTU
Online Link: https://nationaltaiwanuniversity-zbh.my.webex.com/nationaltaiwanuniversity-zbh.my/j.php?MTID=m3efd6c4a404b85f1e7a186a89d9b9009

Abstract:
Quantum information needs to be protected by quantum error-correcting codes due
to imperfect quantum devices and operations. One would like to have an efficient
decoding procedure for practical quantum codes, such as toric and surface codes.
Currently the state-of-the-art minimum-weight perfect matching decoder has complexity
polynomial in the code distance; a decoder of complexity linear in the code distance is
desired. A potential candidate is Pearl's belief propagation (BP), but its performance
suffers from the many short cycles inherent in quantum codes. We show that BP can
exploit the degeneracy of quantum codes and have significantly improved performance.
In particular, we achieve a high decoding threshold (14~16%) for the surface codes in
the ideal circuit model.

Biography Brief:
Ching-Yi Lai was born in Taipei, Taiwan. He received his MS in 2006 and BS in
2004 from the Department of Electrical Engineering, National Tsing-Hua University,
Taiwan. He received his Ph.D. degree in 2013 from the Communication Sciences
Institute, Electrical Engineering Department, University of Southern California. He
joined the Centre for Quantum Software and Information, University of Technology
Sydney as a postdoctoral research associate from December 2013 to July 2015. Then he
was a postdoctoral scholar at the Institute of Information Science, Academia Sinica,
Taiwan from September 2015 to July 2018.
Dr. Lai is currently an Assistant Professor at the Institute of Communications
Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan. He
received the Young Scholar Fellowship from the Ministry of Science and Technology,
Taiwan in 2018. His research interests include quantum error-correcting codes, quantum
information theory, fault-tolerant quantum computation, and quantum cryptography.