Our posters are accepted at QPL 2024!

On July 16th, I presented two posters at Quantum Physics and Logic 2024:

  • Improving the fidelity of CNOT circuits on NISQ hardware

  • Graphical derivation of fault-tolerant operations on CSS codes

I learned a lot from the discussions about our results and gained new ideas about the room for improvement. Moreover, it is eye-opening to learn about innovative work in quantum compilation, circuit optimization, completeness results in ZX calculus, and many other directions. I wish to thank everyone at the conference for sharing your knowledge generously and exchanging ideas openly. I’m looking forward to another year of learning and exploring.

Graduating from Master’s of Mathematics from Department of Combinatorics and Optimization , University of Waterloo

Long gone are the days when I was learning about sets in Discrete Mathematics! From 2019 to 2024, from undergraduate research to master’s. 5 years, 6 papers, 3 ongoing works, many talks and stimulating discussions, numerous deadlines, countless late nights, and endless adventures. It has been a wild ride, and I’m grateful for everyone who helped me grow into the person I am today.

I wish to thank my supervisors, Michele Mosca, Julien Ross, and Peter Selinger, who taught me to stay curious about the world, to think outside the box, to be adventurous but down-to-the-earth, to be kind and generous, to work hard but also have fun! Thank you for being so patient with me and believing in me.

I wish to thank Chin Lee for being kind and heartwarming, for being fantastic at her job, for being dedicated to helping us, and for all the chats and laughter.

I wish to thank all my collaborators for helping me grow not only as a researcher, but also as a person. Thank you for your awesomeness and for brightening up my world: Michele Mosca, Priyanka Mukhopadhyay, Vlad Gheorghiu, Lia Yeh, Jiaxin Huang, Michael Vasmer, Aleks Kissinger, Arianne Meijer - van de Griend, Ewan Murphy, Andrew Glaudell, Matthew Amy, Julien Ross, Peter Selinger, Minyoung Kim, and Dohun Kim.

Lastly, I wish to thank my colleagues and mentors at PsiQuantum, I had the coolest internship I could have ever dreamed of. Thank you for welcoming me into the team, for sharing your knowledge, and all the inspiring conversations. This internship allows me to put everything in perspective, and it directly motivates the research focus of my PhD.

For everyone who I’m fortunate to meet along the journey, thank you for inspiring me and teaching me. I feel so lucky to be a part of the booming and growing quantum community.

I’m super proud of myself, for not giving up, for always being positive, for doing many things not perfectly but thoroughly, for collaborating with talented minds and learning from them, for accepting failure and rejections, for celebrating my success, and for pushing forward until the last minute.

Dear Sarah, I think you will be an amazing person, and I hope you live every day to its fullest as if it is your last day on earth.

To 2024 ~

Subset at the Park City, Utah, USA

Photo Credit: Sarah Meng Li

大部分事情的的进程，好像都是违背念想的。

我们希望既快又好地做完一件事，但是往往好事多磨，欲速则不达。我们希望在年轻的时候一鸣惊人，但最隽永的深度要依仗岁月里漫长静默的积累。我们追求自由，但大部分的游戏规则要求我们带着镣铐跳舞。我们渴望被理解、被认可、被接纳，但是被误解又是表达者的宿命。我慢慢体会到，生活很复杂，世界很喧闹，因为我们只能看到自己的一隅，所以大部分的时候都在被动地应对、狼狈地披荆斩棘。因为视野的局限性，我们无法估量每一件事情的价值，所以也不知道自己到底做了多少贡献。因为每一件的事情，都在各种要素的协同左右下变化发展，我无法定义成功、定义失败，甚至也很难定义如愿以偿。

可是生活也很简单，因为我们只管得了自己，所以只要做我所爱，爱我所做，我的世界每天便是明确且灿烂的。以人生的尺度来看，在我告别这个世界的时候，唯一重要的只是我的体会。至于来自他人的评价，每一件事情的价值与回报，好像也不那么重要了。

如同到了秋天金黄色的落叶，隆冬里新鲜的雪，早春稚嫩的风，盛夏里热烈的蝉鸣。他们虽然只是短暂又客观地存在过，可当我想起他们，想起的是那个感受过四季的变化的我，这些有限的存在便跨越了时间。

还有半年，我就要28岁了。我感到幸运，因为时刻做着自己热爱的工作，每天都在过关斩将，大部分的时间因为自己能力有限而惶恐，但是因为看到自己的成长，每一天都很可爱。

我希望自己在27岁最后的六个月里，可以包容所有的变数，从容不迫并执着不懈地为自己争取，不争辩，不犹豫，不气馁。扶持后辈，与同辈协作，向前辈学习。用心做好每一件事，顺其自然。

I graduated from Google's CS Research Mentorship Program!

In December 2023, I graduated from Google’s CS Research Mentorship Program, which aims to support students from historically marginalized groups by matching them with peers and a Google mentor to support their pursuit of computing research pathways. 

I wish to take a moment to thank my mentor William J. Huggins for all the inspiring chats and encouragement. I am grateful to be part of this wonderful ride and I wish to thank the Google CSRMP team for making this possible.

This year, I was one of 15 alum invited to return to speak on a panel and present my research on Graphical CSS Code Transformation Using ZX Calculus to the current class of 203 students! Click here to check out my presentation!

Learn more about the program at g.co/CSRMP.

Our ZX-CSS paper was accepted at QPL 2023!

We are super thankful to receive constructive feedback from our reviewers, and we working to better our paper for the camera-ready submission. On May 23rd 2023, I will talk about our work at IQC Student Seminar. Looking forward to the enlightening discussion.

This is my first paper on quantum error correction and ZX calculus. It feels surreal that we figured out the problem and our paper was accepted as both a talk and conference proceedings at this year’s QPL. I wish to take a moment to thank my collaborators and myself, for trying all possible ways and never giving up. For contributing collectively and bettering our work until the last minute. I am so grateful and proud that this worked out, and I am beyond motivated to welcome more of her intellectual siblings.

Check out these links for more details! >> Paper >> Poster >> Slides

Excited to teach an introductory QEC workshop!

On Friday Oct 21st, I will teach a workshop titled “A beginner’s guide to quantum error correction“ at Qiskit Fall Fest CIC-IPN Mexico hackathon. It is an English-Spanish language virtual quantum computing hackathon for Mexico and Latin America. Cannot wait to share my passion for QEC with other quantum enthusiasts!

If you want to learn more about quantum computing, online, free and meet people from the industry and academia and get to answer your questions is the opportunity, one week and there will be challenges by Xanadu, Entropica Labs, Agnostiq and Quantum Universal Education, as the open hackathon of Qiskit. Learn about open source and quantum computing and meet Latin American qiskit advocates and how to become one :D

Click here to register!

Our Dynamic Qubit Reallocation paper was accepted at QPL 2022!

Group dinner at Victoria Arms.

Quantum Physics and Logic (QPL) was hosted in-person this year at Oxford, UK. Our paper, Dynamic qubit allocation and routing for constrained topologies by CNOT circuit re-synthesis, was accepted as a talk. We want to thank all the constructive feedbacks from our reviewers to help us better this paper.

Beyond that, I want to thank all of the local organizers for hosting QPL and making it an enriched learning experience.

Our intrel paper was presented at QPL 2021!

The 18th International Conference on Quantum Physics and Logic (QPL) is an annual conference that brings together researchers working on mathematical foundations of quantum physics, quantum computing, and related areas, with a focus on structural perspectives and the use of logical tools, ordered algebraic and category-theoretic structures, formal languages, semantical methods, and other computer science techniques applied to the study of physical behaviour in general. Work that applies structures and methods inspired by quantum theory to other fields (including computer science) is also welcome.

We want to thank our reviewers for your time and feedback. Thank you so much for this great opportunity!

Our redcnot paper was presented at PLanQC 2021!

The Second International Workshop on Programming Languages for Quantum Computing (PLanQC 2021) aims to bring together researchers from the fields of programming languages and quantum information, exposing the programming languages community to the unique challenges of programming quantum computers. It will promote the development of tools to assist in the process of programming quantum computers, both those that exist today and those likely to exist in the near to far future.

We are so grateful for the detailed feedbacks from our reviewers. Your comments provided valuable perspectives and critical evaluation of our work. They will help us further improve our paper and methodologies. Thank you so much for your precious time and amazing insights!

Click here to check out the talks!

Our redcnot paper was presented at TQC 2021!

The 16th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC) is a leading annual international conference for students and researchers working in the theoretical aspects of quantum information science. The scientific objective is to bring together the theoretical quantum information science community to present and discuss the latest advances in the field.

We are very grateful for the constructive feedbacks from our reviewers. Despite a tremensous amount of paper submissions to review, you took time from your busy schedule and provide valuable insights. They will help us further improve our paper and methodologies. Thank you so much for your generous support!

My coauthor Priyanka Mukhopadhyay had presented our work at TQC 2021. Check out her presentation!

2021 Dalhousie University Board of Governors' Awards

Meng Li 11.jpg

Extremely honoured to cap off my undergraduate study at Dalhousie with the 2021 Board of Governor’s Award! So grateful to everyone who has supported me over the past five years.

In 1992, to mark the 125th anniversary of the founding of the Dalhousie Student Union, and to recognize students' contribution to the quality and vitality of the University, the Board of Governors established a set of awards to be known as Governors' Awards.

Click here to learn more about our experience at Dalhousie.

Our redcnot paper was presented at ATCAT & YQIS 2021

Paper: Reducing the CNOT count for Clifford+T circuits on NISQ architectures

Check out Atlantic Category Theory Seminar (ATCAT 2021) and the Sixth International Conference for Young Quantum Information Scientists (YQIS 2021).

Abstract: While mapping a quantum circuit to the physical layer, one has to consider the numerous constraints imposed by the underlying hardware architecture. Connectivity of the physical qubits is one such constraint that restricts two-qubit operations like CNOT to “connected” qubits. SWAP gates can be used to place the logical qubits on admissible physical qubits, but they entail a significant increase in CNOT-count.

In this talk we consider the problem of reducing the CNOT-count in Clifford+T circuits on connectivity constrained architectures. We “slice” the circuit at the position of Hadamard gates and “build” the intermediate portions. We investigate two kinds of partitioning – (i) partitioning the gates of the input circuit based on the locality of H gates and (ii) partitioning the phase polynomial of the input circuit. The intermediate {CNOT,T} sub-circuits are synthesized using Steiner trees, similar to the work of Nash, Gheorghiu, Mosca in 2020 and Kissinger, de Griend in 2019. Our algorithms have certain procedural differences that also help to further reduce the CNOT-count. In our experiment, we compared the performances of our algorithms while mapping different benchmark circuits as well as random circuits to some popular architectures like 9-qubit square grid, 16-qubit square grid, Rigetti 16-qubit Aspen, 16-qubit IBM QX5, 20-qubit IBM Tokyo. We found that for both the benchmark and random circuits our first algorithm using the simple slicing technique performs much better i.e. gives much less CNOT-count than the count obtained by using SWAP gates. Our second slice-and-build algorithm performs reasonably well for benchmark circuits.

I completed my honours presentation today!

Thesis: Global Synthesis for 3-Qubit Restricted Clifford+T Circuits

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Abstract: We describe a global synthesis method for the group O8(Z[1/2]) of 8-dimensional orthogonal matrices with entries in Z[1/2]. This group arises in the study of quantum circuits, and it corresponds to the group of 3-qubit restricted Clifford+T circuits composed of NOT, CNOT, Toffoli, and an analogue of the Hadamard gate. Our method achieves a bound of O(k) gates using decomposition into 1-, 2-, and 4-level operators which was first proposed by Amy, Glaudell, and Ross in 2020.

Our intrel paper was presented at IWQC 2020

Paper: Generators and relations for the group of Orthogonal Dyadic operators

Check out the 4th International Workshop on Quantum Compilation (IWQC 2020).

Abstract: We give a finite presentation by generators and relations for the group On(ℤ[1/2]) of n-dimensional orthogonal matrices with entries in ℤ[1/2]. We then obtain a similar presentation for the group of n-dimensional orthogonal matrices of the form (1/2)^kM, where k is a nonnegative integer and M is an integer matrix. Both groups arise in the study of quantum circuits. In particular, when the dimension is a power of 2 the elements of the latter group are precisely the matrices that can be represented by a quantum circuit over the universal gate set consisting of the Toffoli gate, the Hadamard gate, and the computational ancilla.