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Alexis Morvan

@amorvan.bsky.social

150 followers 64 following 36 posts

Quantum Research Scientist at Google Quantum AI

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Alexis Morvan @amorvan.bsky.social · Dec 20

We just put on arXiv a long haul work on "bending" the time-dynamic of the surface code. We demonstrate error suppression from distance 3 to 5 for three different implementations on Willow. The three offer uniques venues for designing new hardware for error corrections.

arxiv.org/abs/2412.14360

End cycle stabilizer representation for four surface code implementation: Standard, the standard implementation used so far by every experiments. Hexagonal, where the surface code uses only gates on a hexagonal lattice. The end cycles of even and odd are different. The Walking implementation where data and ancilla exchanges roles and the iSWAP implementation that uses an iSWAP instead of a CZ/CNOT, giving the stabilizer the shape of arrowhead.

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Reposted by Alexis Morvan

University of Rochester @urochester.bsky.social · 1d

The same quantum tunneling honored by this year’s #NobelPrize is driving #URochesterResearch

@machielblok.bsky.social is building quantum systems that do what classical computers can’t—inspired by the same fundamental questions

uofr.us/48o7I0K

#QuantumPhysics #QuantumComputing

Quantum tunneling: URochester physicist explains a Nobel Prize–winning discovery

Machiel Blok’s research in superconducting circuits builds on the quantum tunneling effects recognized by the 2025 Nobel Prize in Physics.

uofr.us

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Alexis Morvan @amorvan.bsky.social · 3d

Well, so much for my post about learning something new this Nobel week! The Physics prize went to J. Clarke, M. Devoret, and J. Martinis, the pioneers of my own field, superconducting circuits. An absolutely foundational work, and so well-deserved.

www.nobelprize.org/prizes/physi...

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Alexis Morvan @amorvan.bsky.social · 4d

Nobel Prize week is almost here. I enjoy the predictions, but the real highlight for me is the forced exposure to science outside my field. It’s the one week I get a proper dive into research I’d otherwise miss.

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Alexis Morvan @amorvan.bsky.social · 11d

With my son, we played with vegetal oil, baking powder and vinegar colored in blue. The effect was really cool!

Alexis Morvan @amorvan.bsky.social · 12d

scottaaronson.blog?p=9170
Scott Aaronson on the recent « quantum advantage » claim.

My favorite quote from his comment:
« When they simulate the noiseless quantum computation classically, the advantage disappears? WTF? »

HSBC unleashes yet another “qombie”: a zombie claim of quantum advantage that isn’t

Today, I got email after email asking me to comment on a new paper from HSBC—yes, the bank—together with IBM. The paper claims to use a quantum computer to get a 34% advantage in predic…

scottaaronson.blog

Reposted by Alexis Morvan

Craig Gidney @craiggidney.bsky.social · 25d

Blog post: "Actually, you can't test if quantum uses complex numbers" algassert.com/post/2501

I doom the concept of that 2021 Nature paper by showing how to compile any distributed quantum protocol into real-only gates while preserving locality.

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Reposted by Alexis Morvan

Arthur Pesah @arthurpesah.bsky.social · 27d

This work started w/ my struggle to understand fault-tolerant cluster states, and in particular why they always magically implement the same QEC problem as non-MBQC circuits. Understanding this correspondence as chain complex equivalence finally solved it for me, and I hope for other people too :)

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Reposted by Alexis Morvan

Craig Gidney @craiggidney.bsky.social · Aug 31

Been awhile since I wrote a blog post.

Anyways... why haven't quantum computers factored 21 yet?

algassert.com/post/2500

Why haven't quantum computers factored 21 yet?

Craig Gidney's computer science blog

algassert.com

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Reposted by Alexis Morvan

John Preskill @preskill.bsky.social · Aug 17

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

QEC25

qec25.yalepages.org

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Alexis Morvan @amorvan.bsky.social · Aug 23

Amazing !! Thank you!
Congratulation on the manuscript!

Alexis Morvan @amorvan.bsky.social · Aug 22

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!

Colour Codes Reach Surface Code Performance using Vibe Decoding

Two-dimensional quantum colour codes hold significant promise for quantum error correction, offering advantages such as planar connectivity and low overhead logical gates. Despite their theoretical ap...

arxiv.org

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Alexis Morvan @amorvan.bsky.social · Aug 18

The recording of my talk on the Implementing the surface code using dynamic circuits at QEC2025 is available online!

yale.hosted.panopto.com/Panopto/Page...

QED25 - Int'l Quantum Conf; Day 1, Recording 2

yale.hosted.panopto.com

Alexis Morvan @amorvan.bsky.social · Aug 14

Nvidia is releasing their open source tensor network decoder! As a small bonus they used experimental data from the google surface code experiemnt of 2023. I wonder how it would perform on more recent datasets developer.nvidia.com/blog/streaml...

Streamlining Quantum Error Correction and Application Development with CUDA-QX 0.4 | NVIDIA Technical Blog

As quantum processor unit (QPU) builders and algorithm developers work to create large-scale, commercially viable quantum supercomputers, they are increasingly concentrating on quantum error…

developer.nvidia.com

Alexis Morvan @amorvan.bsky.social · Aug 12

Looks like 3-coupler / hex implementation of the surface code can now tolerate dropout! www.arxiv.org/abs/2508.08116

Handling fabrication defects in hex-grid surface codes

Recent work has shown that a hexagonal grid qubit layout, with only three couplers per qubit, is sufficient to implement the surface code with performance comparable to that of a traditional four-coup...

www.arxiv.org

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Alexis Morvan @amorvan.bsky.social · Aug 10

I will be at the #QEC25 conference at Yale this week! I will be giving a talk on our work on dynamic implementation of the surface code on Monday

Reposted by Alexis Morvan

Craig Gidney @craiggidney.bsky.social · May 23

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

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Alexis Morvan @amorvan.bsky.social · May 16

Pretty cool work on qudit encoded in GKP.

I think this is also the first experimental demo of a Error Corrected Qudit

www.nature.com/articles/s41...

Quantum error correction of qudits beyond break-even - Nature

Quantum error correction of a logical qutrit and ququart were experimentally realized beyond the break-even point with the Gottesman–Kitaev–Preskill bosonic code.

www.nature.com

Alexis Morvan @amorvan.bsky.social · May 15

Let’s be honest. It’s hard to beat the Surface code!

Craig Gidney @craiggidney.bsky.social · May 14

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.

Alexis Morvan @amorvan.bsky.social · May 4

Detecting region with ZX calculus!

arxiv quant-ph @arxiv-quant-ph.bsky.social · Jun 13

Hector Bombin, Daniel Litinski, Naomi Nickerson, Fernando Pastawski, Sam Roberts
Unifying flavors of fault tolerance with the ZX calculus
https://arxiv.org/abs/2303.08829

Alexis Morvan @amorvan.bsky.social · Apr 25

Now, if you ask the question the other way of how many circuit constructions would do that, there might be only this one?

Alexis Morvan @amorvan.bsky.social · Apr 25

My guess as to why the 3-coupler wasn't discovered before is that it shifts around the flavor of the stabilizers.

If you look at the stabilizer at the end of the cycles, for a given measurement qubit in the bulk, the color changes every other round. The 'ear' of the surface code patch shifts a bit.

The two end of cycles of the surface code with 3-couplers

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Reposted by Alexis Morvan

Craig Gidney @craiggidney.bsky.social · Apr 7

Tomorrow I'm giving a zoom talk on magic state cultivation at the Simons quantum Colloquium.

Apr 8, 10am PST, see simons.berkeley.edu/programs-eve...

Cultivation is the (current) culmination of a decade of work ending the reign of T gates as the dominant cost in fault tolerant quantum computation.

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Alexis Morvan @amorvan.bsky.social · Apr 2

Largest factorization done on a quantum computer.

Joke aside. That is an extremely instructive work!

Craig Gidney @craiggidney.bsky.social · Apr 1

For sigbovik, I factored all 8 bit ints (up to 255) with a quantum computer github.com/strilanc/fal...

I did it as legit as I possibly could. I ran a correct circuit with no optimization shenanigans. I did correct pre/postprocessing.

It took 121 quantum samples to finish the entire task.

But...

Alexis Morvan @amorvan.bsky.social · Mar 26

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!

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Alexis Morvan @amorvan.bsky.social · Mar 22

I really enjoyed the MM session on early history of quantum information. It was really uplifting to listen to.

I really love old lab notes, notes and written mails communications from these days. Look way more fun than emails and chat messages we have these days