New paper out β¨
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 (π) in a few tweets (and memes!)
New arXiv preprint: we show algorithmic versions of the polynomial FreimanβRuzsa (PFR) theorem of Gowers, Green, Manners, and Tao. Interestingly, our proof draws on quantum information and stabilizer learning algorithms, which we dequantize into classical algorithms.
arxiv.org/pdf/2509.02338
Correction: the talk will start at 12:30 ET
come listen to @csenrui.bsky.social talk about his recent work at tomorrows seminar on the UF discord. It's open to anyone to attend :)
It took me a while, but I (finally) wrote a "short" (erm) note on the "polynomial+moments method" to prove testing or indistinguishability sample complexity lower bounds. Including the infamous Ξ©(k/log k) tolerant uniformity testing one.
Comments and feedback welcome!
π github.com/ccanonne/pro...
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
UChicago PME Quantum Engineering PhD student Su-un Lee is spending the summer interning with the #quantum algorithms team at IBM.
Read his Q&A in UChicago PMEβs Engineering the Summer series: pme.uchicago.edu/news/enginee...
Title: Unitary designs in nearly optimal depth, Abstract: We construct Ξ΅-approximate unitary k-designs on n qubits in circuit depth O(log k log log nk/Ξ΅). The depth is exponentially improved over all known results in all three parameters n, k, Ξ΅. We further show that each dependence is optimal up to exponentially smaller factors. Our construction uses Γ(nk) ancilla qubits and O(nk) bits of randomness, which are also optimal up to log(nk) factors. An alternative construction achieves a smaller ancilla count Γ(n) with circuit depth O(k log log nk/Ξ΅). To achieve these efficient unitary designs, we introduce a highly-structured random unitary ensemble that leverages long-range two-qubit gates and low-depth implementations of random classical hash functions. We also develop a new analytical framework for bounding errors in quantum experiments involving many queries to random unitaries. As an illustration of this framework's versatility, we provide a succinct alternative proof of the existence of pseudorandom unitaries.
What is the min depth you need for a random unitary?
In this work w/ Tommy Schuster, @RobertHuangHY, Fernando BrandΓ£o (arxiv.org/abs/2507.06216) we glue random unitary blocks w/ only random phases on log n qubits (fns on log n bits) to get designs in d = log k log log n π§©
1/8
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...
A theoretical basis for this work is the Gate-set Pauli noise learning framework (arxiv.org/abs/2410.03906) which gives efficient parameterization of gauge parameters in a quasi-local Pauli noise model.
I recently post a notebook illustrating the basic ideas there: github.com/csenrui/Paul...
An exciting collaboration with Edward H. Chen, Laurin E. Fischer, Alireza Seif, Liang Jiang, and other colleagues from IBM Quantum and UChicago.
πͺDisambiguating Pauli noise in quantum computers
scirate.com/arxiv/2505.2...
Quantum noise characterization suffers from "gauge ambiguity" due to noisy initialization and measurements. We show this does not stop us from correctly mitigating errors, both in theory and in up to 92-qubit experiments
I'm hiring a postdoc! If you'd like to work with me on quantum learning, error correction, quantum algorithms, and FTQC at Virginia Tech in the Washington, DC metro area, please apply here: careers.pageuppeople.com/968/cw/en-us...
Thank you, Evan! π
Thank you Greg π!
Thank you Jonathan! Congrats on your recent new position, too!
Hi Felix, thank you! I am starting as a postdoc at Caltech this summer. Will likely continue to work on related directions.
Thank you, Graeme!
I defended my PhD dissertation today!! πΎπβοΈ
Thank you to everyone who supported me along this wonderful journey!
Excited to share our first major result from our IARPA Entangled Logical Qubits team!
arxiv.org/abs/2504.07258
@benbrown.bsky.social @universal-soup.bsky.social @evanhockings.bsky.social @georgianixon.bsky.social
1/n I'm excited to share our latest work, Demonstration of robust and efficient quantum property learning with shallow shadows, published in Nature Communications! π
π Authors: Hong-Ye Hu, Andi Gu, Swarnadeep Majumder, Hang Ren, Yipei Zhang, Derek S. Wang, Yi-Zhuang You, Zlatko Minev,
Won APS ducks at #APSSummit25 #apsmarch with Su-un Lee and Kento Tsubouchi
Only one week left to submit a contributed talk to QEC 25!
qec25.yalepages.org
August 11 - 15, 2025, hosted at Yale University.
This promises to be the best QEC yet!
Please repost!
Heading to Anaheim for #APSSummit25 #apsmarch.
I will be giving two talks, both on Monday:
1β£ Efficient self-consistent learning of gate set Pauli noise, 10:24 β 11:00, 258A
2β£ Generalized cycle benchmarking algorithm for characterizing mid-circuit measurements, 3:36 - 3:48, 256B
Why characterise noise in syndrome extraction circuits? One reason: directly improving quantum error correction!
In simulations of the surface code, we find that noise-aware decodingβcalibrating the decoder with noise estimatesβimproves the code's error suppression factor.
1/n I am stepping away from IBM Quantum after nearly 7 years. This was an unforgettable chapter of my life where I was blessed with the best of colleagues, on a joint mission to bring useful quantum computing to the world, and to help bring up the next generation of young scientists.
Stepping away
If qubits only talk to 1D neighbors, is constant rate fault tolerance possible?
Last year I referee'd a paper claiming it wasn't. My review was "this is wrong but the constructive disproof is too large for this review".
Clearly a reviewer 2 move. Sorry. But I was right! scirate.com/arxiv/2502.1...
Check out our recent pre-print: arxiv.org/abs/2502.01864
In this work, we construct the first quantum codes which support transversal and addressable non-Clifford gates!
When in Canada, use a hockey stick! @markwilde.bsky.social delivers his talk on quantum hypothesis exclusion at the Perimeter Institute with a true Canadian twist π
