Sunny He

Don't know what Quantum Youtube is, but 👍

Parsimonious Quantum Low-Density Parity-Check Code Surgery Quantum code surgery offers a flexible, low-overhead framework for executing logical measurements within quantum error-correcting codes. It encompasses several fault-tolerant logical computation schem...

Good old code surgery, now more parsimonious than ever.

arxiv.org/abs/2603.05082

Joint work with amazing collaborators Andrew Yuan, Alex Cowtan, David Lin, and Dom Williamson.

This is joint work with amazing collaborators Katie Chang, Ted Yoder, Guanyu Zhu, and Tomas Jochym-O'Connor 😎

YouTube video by Quantum @ Sydney Coogee '26 Talks - Alex Cowtan (Xanadu)

Gave a talk recently at Coogee on constructing and analysing spacetime volumes of LDPC codes & surgeries thereof. Thanks to @sunnyhe.bsky.social @domwilliamson.bsky.social and Ted Yoder for the wonderful collaboration. www.youtube.com/watch?v=Lxzw...

Constant-Time Surgery on 2D Hypergraph Product Codes with Near-Constant Space Overhead Generalized code surgery is a versatile and low-overhead technique for performing fault-tolerant computation on quantum low-density parity-check (qLDPC) codes. In many settings, surgery exhibits pract...

Quantum code surgery: fast, addressable, parallel, (almost) constant space overhead, all at once on your favorite hypergraph product codes.

arxiv.org/abs/2603.021...

Opportunities in full-stack design of low-overhead fault-tolerant quantum computation Nature Computational Science - Quantum error correction is vital for scalable quantum computing, but it incurs high resource overheads. This Perspective outlines recent breakthroughs and explores...

Excited to share our perspective article, written with Maddie Cain and Misha Lukin, on designing low-overhead fault-tolerant architectures: rdcu.be/eVTiB. The landscape is rapidly evolving, and excited to see where the field goes next!

Fault-tolerant logical measurement just got a lot faster!

In new work, we show that code surgeries based on hypergraphs, rather than graphs, allow fast and parallel fault-tolerant logical measurements with low qubit overhead (without requiring the code to be single-shot).

arxiv.org/abs/2510.14895

Fast and fault-tolerant logical measurements: Auxiliary hypergraphs and transversal surgery Quantum code surgery is a promising technique to perform fault-tolerant computation on quantum low-density parity-check codes. Recent developments have significantly reduced the space overhead of surg...

Quantum code surgery, but get them for constant time a piece if you run many of them.

arxiv.org/abs/2510.14895

Joint work with Alex Cowtan, Dom Williamson and Ted Yoder.

A meme on how arXiv/quant-ph and scirate is currently flooded with QIP submissions. quant-ph is depicted as a city upon which three tidal waves of increasing height are collapsing. The smallest one is titled "< 8 Oct", the middle one "QIP papers 9 Oct" and the largest one "QIP papers 10 Oct".

Layer codes as partially self-correcting quantum memories We investigate layer codes, a family of three-dimensional stabilizer codes that can achieve optimal scaling of code parameters and a polynomial energy barrier, as candidates for self-correcting quantu...

Have you heard of high-density parity-check codes before? Anyways, layer codes with random HDPC input codes have provable and numerical partial self-correction properties.

arxiv.org/abs/2510.06659

Joint work with Shouzhen Gu, Libor Caha, Shin Ho Choe, Aleksander Kubica, and Eugene Tang.

Characterization of permutation gates in the third level of the Clifford hierarchy The Clifford hierarchy is a fundamental structure in quantum computation whose mathematical properties are not fully understood. In this work, we characterize permutation gates -- unitaries which perm...

Check it out: permutation unitaries in the 3rd level of the Clifford hierarchy whose inverses escape any fixed, finite level of the hierarchy.

arxiv.org/abs/2510.04993

Joint work with Luke Robitaille and Xinyu (Norah) Tan.

Can ChatGPT help with research? Maybe not yet for finding new results, but it can certainly speed up some tedious tasks.

An example about quantum Tanner codes #qLDPC
Working with qudits (d=5) lets you use nice local codes [4,2,3]_5. Then the idea is simply to enumerate small groups and (1/4)

Peter Shor receives a small gift on the 30th anniversary of his QEC paper at #QEC2025.

Very exciting announcement, the next Quantum Error Correction conference QEC26 will be hosted by Google 7-12 June 2026 in Santa Barbara. See you there! @dripto.bsky.social @mattmcewen.bsky.social

Composable Quantum Fault-Tolerance Proving threshold theorems for fault-tolerant quantum computation is a burdensome endeavor with many moving parts that come together in relatively formulaic but lengthy ways. It is difficult and rare ...

Fault-tolerance is, at its core, a combinatorial study.
arxiv.org/abs/2508.08246

The QIP 2026 call for papers is out! QIP 2026 will be held in Riga, Latvia from January 24–30, 2026. See you there!
qip2026.lu.lv

The slides are posted here: sunnyzhiyanghe.github.io/files/Extrac...

Simons was fun as always, many thanks to the organizers of the reunion workshop!

YouTube video by Simons Institute for the Theory of Computing Extractors: Building a Quantum Computer with QLDPC Codes

In May I gave a talk at Simons about our recent work on extractors architectures, which is a surgery-powered proposal to perform universal Pauli-based computation on any QLDPC codes, with reasonable overheads.
arxiv.org/abs/2503.10390

The talk recording is here:
www.youtube.com/watch?v=L6cDAbaW2Zs

We spent a wonderful summer (and months after) designing, running and analyzing this experiment. It was magical seeing theoretical predictions being observed in practice. Many, many thanks to my amazing collaborators at QuEra and Harvard!

Our paper on logical magic state distillation was just published in Nature! www.nature.com/articles/s41...

Asymptotically Good Quantum Codes with Addressable and Transversal Non-Clifford Gates Constructing quantum codes with good parameters and useful transversal gates is a central problem in quantum error correction. In this paper, we continue our work in arXiv:2502.01864 and construct the...

New preprint out!!

scirate.com/arxiv/2507.0...

Here, we follow up our previous work by constructing the first asymptotically good quantum codes to have transversally addressable non-Clifford gates.

IQC and Waterloo mourn the loss of Raymond Laflamme | Institute for Quantum Computing | University of Waterloo Raymond Laflamme, a trailblazer in quantum information processing and pioneer of the Institute for Quantum Computing (IQC) at the University of Waterloo, died on June 19 after a lengthy battle with ca...

Raymond Laflamme 1960-2025. A great scientist, renowned for his pioneering contributions to quantum error correction. A great leader, founding director of the Institute for Quantum Computing. A great colleague and teacher whose legacy continues to inspire us.
uwaterloo.ca/institute-fo...

Improved belief propagation is sufficient for real-time decoding of quantum memory We introduce a new heuristic decoder, Relay-BP, targeting real-time quantum circuit decoding for large-scale quantum computers. Relay-BP achieves high accuracy across circuit-noise decoding problems: ...

The paper presented solid benchmarking results, utilizing their recent work on Relay-BP, a BP-only decoder that is out-performing BP+OSD in their numerics. arxiv.org/abs/2506.01779. The fitted error rates come from an upcoming work, which I’m really looking forward to. See their Appendix A.7.

In section 1 the paper discussed a list of bicycle instructions, which are native operations supported on this architecture. So for everyone wondering “what logical operations are easy/reasonable on the BB codes”, here is your answer!

Tour de gross: A modular quantum computer based on bivariate bicycle codes We present the bicycle architecture, a modular quantum computing framework based on high-rate, low-overhead quantum LDPC codes identified in prior work. For two specific bivariate bicycle codes with d...

Amazing work from the IBM Quantum team on the bicycle architecture, a proposal for a modular quantum computer built using bivariate bicycle codes as memory and code surgery + automorphisms + T state factory for universal computation. arxiv.org/abs/2506.03094

It's a thrill to announce names of the amazing set of theory people joining NYU CS+CSE this year: @aineshbakshi.bsky.social, Allen Liu, @fermima.bsky.social, Sanjeev Khanna, Tony Metger, and Juan Perdomo.

@nyucourant.bsky.social
@nyutandon.bsky.social

Improved belief propagation is sufficient for real-time decoding of quantum memory We introduce a new heuristic decoder, Relay-BP, targeting real-time quantum circuit decoding for large-scale quantum computers. Relay-BP achieves high accuracy across circuit-noise decoding problems: ...

Great work by the IBM Quantum team on Relay-BP, a BP-only heuristic decoder for general qLDPC codes. From a first look, the performance seems strong and further supports qLDPC architectures from a decoding-focused perspective.
arxiv.org/abs/2506.01779

I'm often asked if I'll redo the 2019 quantum factoring estimate. Denser storage by yokes, smaller magic factories by cultivation, slimmer approx arithmetic by Chevignard et al… surely the cost is lower now?

Yes, it's lower now.

security.googleblog.com/2025/05/trac...

arxiv.org/abs/2505.15917

Mike finally paid for the "pro" version of sketchup, so we owned the 3d models attached to the paper, meaning the yoked surface codes paper is now published! www.nature.com/articles/s41...

The message of this paper is: anytime someone says they're 10x better than surface codes, actually it's 4x.

Happy to share that some previous work with @krishnanirudh.bsky.social and @preskill.bsky.social that we call hierarchical codes (2303.04798) was recently published in Quantum! 1/9