COMPSCI 692U: Quantum Error Correcting Codes

Spring 2023 Prof. Stefan Krastanov
Prof. Don Towsley
CS 142 Wednesday 12:30-2:20

Website at

Signup page for office hours.

The first few weeks of this course will consist of introduction to classical and quantum error correction through lectures by the instructors. After the introduction is completed, we will transition to the seminar part of the course where students will be studying and presenting recent advancements in quantum error correction. The main focus would be on topological codes like the surface and toric codes, and on good quantum codes like the recently developed quantum LDPC codes.

Students can register for either:

  • one credit section where student will be expected to study the various provided papers on the topic and make at least one class presentation on such paper;
  • three credit section which includes the above requirements and, in addition, students will be expected to propose and complete a course project in consultation with the instructors

Students will be expected to fully participate in classroom discussions. Class time will be focused on:

  • Short presentations by students
  • QnA with students, led by the presenting student and moderated by instructors
  • Each presenting student would be expected to discuss their presentation a week in advance with the instructors, in order to polish their presentation and get help on topics of interest. It is the student's responsibility to sign up for office hours!!!

Each paper presentation will be 20min followed by 10-15min of QnA. The presenter's goal should be to teach the audience about the concepts presented in the paper, why are they valuable, how they might be applied, etc. The 10-15min QnA would be managed by the instructors, who will also try to help with the thornier questions.

This course will be executed together with similar concurrent gatherings at partner universities at the NSF Center for Quantum Networks.

Learning Outcomes

Upon completion of this course, it is expected that students will be able to:

  • Simulate the performance of error correcting codes
  • Design a variety of error correction circuits based on a given error correcting code
  • Evaluate properties of error correcting codes analytically and numerically
  • In particular, students will be comfortable with important classes of codes like Surface Codes and LDPC Codes

Required Texts and Materials

A list of general Quantum Information textbooks is made available and a list of papers for each week will be provided in advance.


We will aim to cover the following topics (numbers in parentheses indicate approximate number of 120-minute lectures for each topic):

Calendar and recordings

(the recording links will expire at the end of the semester)

Feb 8 Intro with computational examples based QuantumClifford.jl rec 1
Feb 15 Required watching of a Youtube lecture from the CQN Winter school rec yt
Feb 22 Stabilizer method and its improvements rec 2
Mar 1 Early works and tutorials on QEC, including Steane and Shor rec 3
Mar 8 Nielsen and Chuang's section on QEC (in 3 separate presentations) rec 4
Mar 15 Spring Recess
Mar 22 Surface/Toric codes and their decoding with a WMPM decoders (separate presentation) rec 5
Mar 29 Biased surface codes and then switching topics to classical LDPC codes and BP decoders (not based on a paper) rec 6
Apr 5 Heuristics for the BP algorithm and an early overview of why qLDPC codes are worthwhile rec 7
Apr 12 Sparse eECC from the very early era and a mid-era overview of progress in qLDPC decoding rec 8
Apr 19 Early non-terrible qLDPC codes and new theoretically-great qLDPC codes rec 9
Apr 26 Digression to discuss expander graphs and their use in codes rec 10
May 3 Good decoders (small-set flip iterative decoders) rec 11
May 10 Good decoders (ordereded statistics decoders) rec 12
May 17 Project Presentations rec 13.a and rec 13.b


The grade would be weighted as:

  • 80% from oral presentations
  • 20% from participation in discussions

For students engaging in class projects it would be:

  • 70% from class project
  • 20% from oral presentations
  • 10% from participation in discussions

Remote Participants

Non-local participants from the partner institutions will join us over video conference through Zoom.