Michael Vasmer

We have seminars every two weeks. I am finding it a very useful way to keep up with the volume of great QEC papers at the moment!

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📣 Online QASAR seminar next week

🗣️ Guanyu Zhu (IBM)
📜 Topology for qLDPC: Transversal non-Clifford gates and magic state fountain on homological product codes
⏰ Weds 22 October 5pm (Paris)

Mailing list
sympa.inria.fr/sympa/subscr...

Coming out of social media hibernation to ask:

Are you interested in hosting a future QEC conf?

We are looking for detailed bids for QEC27 over the next month (provisional deadline 21st November). For more info: DM or email me.

QEC26 will be in Santa Barbara

Fast surgery for quantum LDPC codes Quantum LDPC codes promise significant reductions in physical qubit overhead compared with topological codes. However, many existing constructions for performing logical operations come with distance-...

happy to share this preprint from last week scirate.com/arxiv/2510.0... - my first with Iceberg!
big thanks to Larry and Nouedyn, who led this cool project ❄️

we have also written a short blogpost about it www.iceberg-quantum.com/blog/fast-su...
comments welcome 🧊

Efficient and optimal quantum state discrimination via quantum belief propagation We present an efficient quantum algorithm for a structured state discrimination problem we call the subspace decoding task. Building on this, we show that the algorithm enables efficient and optimal d...

Really excited about our new paper on quantum belief propagation (aka "belief propagation with quantum messages")!
arxiv.org/abs/2509.19441
Our new quantum algorithm solves a structured state discrimination problem which is central for quantum algorithm based on Regev's reduction (like DQI).

1/3

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)

New paper out ✨

Fault-tolerant Transformation of Spacetime Codes, a collaboration w/ @vasmer.bsky.social, Austin Daniel & Ilan Tzitrin, which started during my internship @xanaduai.bsky.social

scirate.com/arxiv/2509.0...

Let's now see if I can summarize 101 pages (🙈) in a few tweets (and memes!)

I've had a great time at the Stable Phases program at the Kavli Institute for Theoretical Physics! I'm looking forward to being back in Paris but I will miss the SoCal weather ☀️

Looking for a postdoc to work on bosonic quantum error correction!
Join me and the QAT team at ENS & INRIA Paris — flexible start date.
Details here 👉 recrutement.inria.fr/public/class... or feel free to reach out!

The QEC25 conference hosted by @yaleqi.bsky.social was really excellent, and videos of all talks are available. So much recent progress on quantum error correction!
qec25.yalepages.org

Google Scholar Is Doomed Academia built entire careers on a free Google service with zero guarantees. What could go wrong?

Since search is dead, how soon do you think Google Scholar is headed for the Google Graveyard? I'm betting it's soon, and academia is NOT prepared

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

I am attending the QEC conference at Yale this week. Looking forward to seeing some interesting talks, catching up with old friends, and eating som New Haven pizza!

QIP2025

#Quantum #QIP2025
The team @qip2025.bsky.social has uploaded the QIPv2025 talks

www.youtube.com/@QIP2025

Enjoy rewatching your favorites!

Understanding Quantum Information and Computation This is a course on the theory of quantum computing. It consists of 16 lessons, each with a video and written component, covering the basics of quantum information, quantum algorithms (including query...

After 3 1/2 years of work my course on quantum computing is finally finished — the "Director's Cut" of Understanding Quantum Information and Computation is now available.

arxiv.org/abs/2507.11536

On July 17-18 a small symposium "Dreams of Quantum" will be held in honor of David DiVincenzo's work and retirement at RWTH Aachen. The event can be attended via Zoom by all. Information about the program of speakers & the Zoom link can be found at www.quantuminfo.physik.rwth-aachen.de/cms/~bmmwed

More details can be found here quriosity.telecom-paris.fr/files/PhD_PH...

If you're interested, want more information, know someone who might be, or would like to apply (CV + cover letter), feel free to contact us at:
paul.hilaire@telecom-paris.fr, michael.vasmer@inria.fr

Paul Hilaire and I are recruiting a PhD student to work on demonstrations of fault-tolerant protocols for near-term quantum hardware (photonics & cold atoms). The focus is on quantum error correction, low-overhead schemes, and actual implementation on hardware

He also taught me that you can be a great scientist and live your life to the full. I remember telling him proudly last year that I had gone on a canoe trip in BC, and his response was that he had recently come back from a canoe trip in the Canadian Arctic!

I will miss his many stories—discovering the 5-qubit code, the genesis of the KLM protocol, adventures with Stephen Hawking—and his sense of humour.

Although he made immense contributions to the field, pioneering both theoretical and experimental quantum error correction, for example, he always wore his accomplishments lightly and showed genuine curiosity in the work of researchers at all levels.

One of the amazing things about working in quantum information science is being able to meet and talk to the pioneers of the subject. I was very lucky not only to have met Ray, but also to have been a postdoc in his group for a number of years.

#newpaper Bosonic codes have a huge potential to reduce the cost of quantum fault tolerance, and many codes look like serious contenders: dual-rail qubit, cat qubit, GKP.
But the Fock space is huge, esp. if you consider multimode encodings, and there are many great codes waiting to be found (1/4)

Thanks, I'll take a look

I agree that looking at the structure of the logical operators in the product code (given by the Kunneth formula) is a good place to start. But one would also need to show that the weight of these operators can't be further reduced by applying stabilisers.

Thanks for your responses. What I would like is a generalisation of the result in Zeng and Pryadko. Their distance bounds only hold when one of the input chain complexes is length 2 (ie a classical code).

A theory of single-shot error correction for adversarial noise Single-shot error correction is a technique for correcting physical errors using only a single round of noisy check measurements, such that any residual noise affects a small number of qubits. We prop...

For context, I think it is well-known that the product of two 2D toric codes gives the 4D toric code. And if the two CSS codes are themselves hypergraph product codes, then we have bounds on all the parameters (see arxiv.org/abs/1805.09271). But I would like to understand the general case 🤔

Technical question: does anyone know of formal results on the hypergraph (or tensor) product of two CSS codes? I am especially interested in lower bounds on the distance of the product code.

I have a new paper out: "Quantum Circuit Lower Bounds in the Magic Hierarchy".🔮🪜
arxiv.org/abs/2504.19966
a thread:

Topological quantum memory We analyze surface codes, the topological quantum error-correcting codes introduced by Kitaev. In these codes, qubits are arranged in a two-dimensional array on a surface of nontrivial topology, and e...

If I had to choose just one (covering topics not in the current draft of Gottesman's book), I would pick arxiv.org/abs/quant-ph.... But I don't think the book and this paper will get you to the state of the art, unfortunately.