Con-cat-enated

Can cat-qubits get away with only ever using (concatenated) classical codes? @pshanahan62.bsky.social and @diego-ruiz.bsky.social investigate and suggest yes! #quantum ⚛️ 🧪

New preprint out with @pshanahan62.bsky.social! We introduce a new error-correcting code for biased-noise qubits. Built from the concatenation of two classical codes, it outperforms the surface and XZZX codes when the noise bias exceeds 7x10^4. arxiv.org/abs/2601.10786

We did some experimental testing of magic state cultivation! arxiv.org/abs/2512.13908 A ~1e-4 end2end infidelity is tricky to measure with tomography, so we checked it vs more cultivation. The full escape stage is too wide for the chip, but we did try ending in the grafted code.

This morning my ChatGPT quota was inexplicably exhausted. It took a while but I pieced it together. Voice mode somehow got activated when I went to bed. The bot then engaged in a 10 hour conversation with my snoring dog, answering questions the pup wasn’t asking and praising him for his insight.

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!)

Hi, I am here! Will mostly post about Quantum Foundations/Computing and Quantum Music.

Color code decoding with some big claim: arxiv.org/abs/2508.15743 I wish they could try to benchmark this decoder against the experimental color code data from arxiv.org/pdf/2412.14256 zenodo.org/records/1423... We are releasing experimental data so people can try out their decoding algorithms!

In closing of #qec2025, we have put up our 1000th code -- the [[8,3,2]] surface code on a cube (aka the Landahl plucky code)! It is a non-CSS code different from the smallest interesting color code. Stabilizer generators are X, Y, or Z strings on the faces. errorcorrectionzoo.org/c/cubic_surf...

Probably the last paper of my PhD! We show that biased-noise qubits can greatly reduce the cost of magic state preparation With high noise bias, just 53 qubits and ~10 error correction cycles are enough to prepare a magic state with logical error≈1e-7 arxiv.org/abs/2507.12511

Le Palais de la découverte a besoin de soutient ! C'est un musée des sciences vraiment réussi et pour tous les âges ! 👉 chng.it/SzH6WkfXH2 ⚛️🧪

High-performance local automaton decoder for defect matching in 1D, happy to share that our new work in with Anthony Leverrier, Mazyar Mirrahimi and @christophe.vuillot.info is now available on the arXiv ! 👀 (1/6)

🧪⚛️🧮

So here it is, my first first-author paper is live on the arXiv arxiv.org/abs/2505.01370

Anyone who can spare an invite to the "global economy dump and pump" signal group chat?

Yes, thanks to @arrr.de and the German National Library of Science and Technology in Hannover (TIB, www.tib.eu) :) bsky.app/profile/arrr...

Quantum is interesting because it is making a transition from one of culture to another. (Has made?) But we can still fight to keep quantum weird!

In 1h (9am PST or 5pm CET) I will give a talk at the QASAR seminar hosted by @vasmer.bsky.social and @christophe.vuillot.info . I will present our work on implementing 3coupler, walking and iSWAP surface codes!

Two talks of Alice&Bob QEC team in parallel this morning: @diego-ruiz.bsky.social presented his new results on distillation with biased-noise qubits: with bias=30 he already gets 150x reduction! I talked about implementing rotor codes So many fun subjects to work on, join our team we are hiring!🐱

I'll be at the @apsphysics.bsky.social March Meeting next week in Anaheim. I have a talk on Friday about quantum rotor codes, protected superconducting qubits and tiger codes in the advances in quantum error correction session. Also come talk to me whenever!

The QEC team at Alice & Bob is hiring ! Come work with me on 🐈 cat codes, 🐅 tiger codes, decoding, biased-noise, distillation, LDPC codes, ... 👇 jobs.lever.co/alice-bob/c0...

First realization of a dissipatively stabilized squeezed cat qubit (a slight variation that we called a moon cat 🌛 actually), it was super interesting to work on this with experimentalists! arxiv.org/abs/2502.07892 My two key takeaways ⬇️⬇️

Our fourth and final tutorial of QIP 2025 is by Dakshita Khurana from UIUC about Quantum Cryptography and TCS (Sun Feb 23, 2-5:30pm, Room 302ABC). Overview below!

Our third tutorial of QIP 2025 is “Quantum error correction: a guided tour" by Victor Albert (@vva.bsky.social) from NIST and QuICS, who will gently introduce and visit increasingly important corners of the mega-field of QEC (Sun Feb 23, 9am-12:30pm, Room 302ABC). Overview below:

Our second tutorial of QIP 2025 is by Hsin-Yuan (Robert) Huang from #Google Quantum AI on Quantum Learning and Certification (Feb 22 Sat, 2-5:30pm, Room 302ABC). Overview below:

QIP 2025 is fast approaching! And we have exciting tutorials lined up on Feb 22-23 (Sat-Sun) right before the conference! First in line, we have Cambyse Rouzé from #inria, whose tutorial will cover Quantum Gibbs Sampling (9am-12:30pm, Room 302ABC).

Happy to share our work with @anthony-leverrier.bsky.social, @christophe.vuillot.info, Jérémie Guillaud and Mazyar Mirrahimi on the LDPC-cat architecture was published in Nature Communications! Thanks to the reviewers for their useful feedback www.nature.com/articles/s41...

🧪 ⚛️ #quantum

Super happy to see our work on the LDPC cat architecture published! What's not to love about cat qubit and LDPC codes? Great collaboration with @diego-ruiz.bsky.social @christophe.vuillot.info Jérémie Guillaud and Mazyar Mirrahimi rdcu.be/d7wtt

The online QASAR seminar will be restarting soon! The scope includes everything related to fault-tolerant quantum computation or quantum error correcting codes. Contact @vasmer.bsky.social or me if you have a talk you want to give. Also if there is a result you really want to hear about let us know!

Circuits Galore! Check out our latest work demonstrating three new circuits for implementing the surface code: arxiv.org/abs/2412.14360 They all perform well below threshold on a device optimised for the standard surface code, but they each open up wild new possibilities for devices.

Interesting paper implementing magic state distillation with neutral atoms: arxiv.org/abs/2412.15165 They're in a weird regime: below the distillation threshold but over the color code threshold. They see improvements!... But hit a ceiling imposed by their d=3 memory error (because d=5 does worse).

We've been getting a lot of questions about alternate QEC codes, and are we looking into any? Yes! Here's experiments for two on Willow. The color code: arxiv.org/abs/2412.14256 Dynamic surface codes: arxiv.org/abs/2412.14360

The "hide the exponential" game Scott Aaronson has complained about for decades is alive and well: arxiv.org/abs/2412.13164 Yes, Shor's algorithm with 3 registers only needs very basic operations. No, you can't pack a 2^2000 level quantum state into 1 oscillator and then operate accurately on it.

Oh this is great! Who said quantum computers had to work with qubits? Turns out it's possible to design a quantum algorithm for factoring that only requires 3 quantum oscillators and a single qubit! (1/4)

I created a transcript of my talk at the Q2B Conference: "Beyond NISQ: The Megaquop Machine." You can read it here: quantumfrontiers.com/2024/12/14/b...

Mathematicians pros do it all the time! They don't even have to come back to it later: [Our hero winning the fight through clever means follows trivially and is left as an exercice to the reader]

You can now BibTeX the thousands of references mentioned in the zoo!

Codewords normalization and overlap are governed by a Gelfand-Kapranov-Zelevinsky (GKZ) hypergeometric function, and we anticipate interesting connections to this deep literature down the road.

Here are slides from my Simons Center for Geometry and Physics talk on tiger codes --- a new paradigm for intrinsically multi-mode many-body CV physics. drive.google.com/file/d/1PKjp...

To all the Gen Z that never had the pleasure of managing your own TeX distribution, today is your day!

Let me know if you want your #quantum tagged posts to be listed in this quantum feed: bsky.app/profile/did:... .

When your baby birds 🪺 won't fall asleep so you have to play the flute for them 🎶

Anyone who's interested can follow our research group on multimode quantum optics here on Bluesky: @mqo-lkb.bsky.social

A peek at some of my slides for quantum industry day at the Simons institute on Thursday, comparing 2014 to 2024. I find myself wondering if 2024 vs 2034 will show similar amounts of improvement. I think it could, if physical qubits keep improving in quality or capability (e.g. non-planar links).

Bluesky now has over 20M people!! 🎉 We've been adding over a million users per day for the last few days. To celebrate, here are 20 fun facts about Bluesky:

New blog post... on Dynamiqs ⚡️ alice-bob.com/blog/dynamiq... With v0.3, we are 60x faster when using GPUs on the simulation of a CNOT between cat qubits (generally replicable on any large open quantum system). Hopefully it's only the beggining 😋

Anybody discussing quantum LDPC codes or bosonic codes around here?

All right! More and more quantum people here! Are we entering the BluesQy Era now?