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Rafael Macêdo

@rafammacedo.bsky.social
118 followers 461 following 21 posts

quantum information theory postdoc @ qmath, copenhagen. all things mathematical and theoretical, i guess! site: sites.google.com/view/rafammacedo

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Reposted by Rafael Macêdo
Alex @itsmealeale.bsky.social · 12h
How much quantum physics can we explore by simply preparing and measuring a system? Very happy to share "Quantum prepare-and-measure scenarios: concepts & methods" (arxiv.org/abs/2610.20725), together with Santiago Zamora , Jonatan Bohr Brask, Rafael Chaves & Armin Tavakoli! Hope u like it!
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John C. Baez @johncarlosbaez.bsky.social · 12/10/2026
We may finally know that for any n, there exist n² unit vectors in ℂⁿ that all lie at the same angle from each other! More precisely, |⟨v,w⟩| is the same for any two different vectors. The proof is crazy hard, and it required a new result in category theory.
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Rafael Wagner @quantumrw.bsky.social · 12/10/2026
I have recently learned about Hexagon hexagonmath.org which is a new repository for research outputs. Here, there are tags indicating how much of it was written by the AI, and also how much of it the human contributors understand.
hexagonmath.org
Hexagon
A repository for research-level works in the mathematical sciences and theoretical computer science.
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Clément Canonne @ccanonne.github.io · 10/10/2026
I wrote a blog post on "TCS, AI, and the Adults in the Room," addressed to the senior researchers and established academics in our field: minorfree.github.io/Clement/ Thanks to @hunglv.bsky.social for lending me his blog!
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Ragnar {Groot Koerkamp} @curiouscoding.nl · 08/10/2026
Turns out 3 of the papers have been retracted based on a sign error in one of them. github.com/openai/math/...
3 withdrawals based on a sign error in a paper on the Algebraicity of Weill classes on split abelian eightfolds.
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Rafael Macêdo @rafammacedo.bsky.social · 08/10/2026
this paper was a quite a personal journey, and the last of my PhD. I learned a lot, and, in the end, I am quite happy that it managed to see the light of the world in the middle of this turbulent AI storm. thanks for (all purposes) my PhD cosupervisor rafa chaves for the believing! 3/n, n=3
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Rafael Macêdo @rafammacedo.bsky.social · 08/10/2026
we showed that it is related to a recent binary classification (entanglement dominated (ED)/magic dominated states (MD) states), and that it is deeply related to entanglement manipulation: Ground states with entanglement area laws that are ED have magic area laws and efficient entanglement 2/n
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Rafael Macêdo @rafammacedo.bsky.social · 08/10/2026
yesterday, among the results released by the internal openAI model, the two-dimensional entanglement area law was shown for gapped ground states. coincidently, we released a new paper asking if magic could also host an area law for ground states, and what it would mean! arxiv.org/abs/2610.08727 1/n
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Nirmalya Kajuri @kajunut.bsky.social · 05/10/2026
Hawking radiation can be derived via -Bogoliubov transforms (Hawking's original 1974 paper, Unruh 1976) -path integrals (Hawking and Hartle, 1976) -stress tensor in 2D (Davies, Fulling and Unruh, 1976) -conformal anomaly (Christensen and Fulling, 1977) -Euclidean BH (Gibbons and Hawking, 1977)
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Greg White @gregswhitenoise.bsky.social · 06/10/2026
New PhD students take note: there can still be so much joy to contribute with human-written manuscripts (from the very nice-seeming arxiv.org/abs/2610.06842)
Screenshot from a paper, quote: "The Umegaki relative entropy has found many natural connections with tasks in quantum information processing, whereas the Belavkin–Staszewski relative entropy has thus far mostly found use as a bound that — while useful in settings where the Umegaki relative entropy is difficult to apply — is not in general tight. Owing both to the initials of the authors who first proposed it, as well as to its seeming lack of operational meaning, 𝐷(𝜌∥𝜎) is thus sometimes referred to as the BS relative entropy."
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Richard Kueng @richardkueng.bsky.social · 02/10/2026
I have been intrigued by the computational complexity of Clifford circuit synthesis since 2023 - motivated by a fun collaboration with Robert Wille+team. Our postdoc Luna Keller now found an elegant argument that settles it: optimal Clifford synthesis is NP-hard. Kudos! scirate.com/arxiv/2610.0...
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Alex @itsmealeale.bsky.social · 01/10/2026
Can a physically motivated symmetry make many-body magic analytically solvable? If so, at what cost? We answer this question (arxiv.org/abs/2609.38319), by looking at pairwise parity symmetry. This gives rise to a family of quantum states known as X-states. (continue..)/n
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Rafael Macêdo @rafammacedo.bsky.social · 28/09/2026
would read :)
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julia 🌋 @hypv.bsky.social · 27/09/2026
she's right, and it generalizes. this is the correct attitude toward education, across all the core areas.
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Rafael Macêdo @rafammacedo.bsky.social · 24/09/2026
very cool guest post by bryna kra in terry's blog regarding the new age of LLM math: terrytao.wordpress.com/2026/09/13/d...
terrytao.wordpress.com
“Deep theorems were scarce and difficult and so became an effective mechanism to identify deep thought. AI has broken this system.”
[This is a guest post by Bryna Kra. This blog post was initially written in a different file format and converted using AI. — T.] For generations, mathematicians have treated the production o…
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Clément Canonne @ccanonne.github.io · 14/09/2026
Big (huge?) news on the computational complexity preprint server, with a paper by Yumou Fei, Dor Minzer, and Shuo Wang I am not qualified to read beyond the intro: the perfect completeness version of the (not) Unique Games Conjecture, the 4-to-1 Games conjecture! eccc.weizmann.ac.il/report/2026/...
eccc.weizmann.ac.il
ECCC - TR26-179
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Erfan Mirzaei @erfunmirzaei.bsky.social · 14/11/2025
🧵Thermodynamics Reveals the Generalization in the Interpolation Regime In the realm of overparameterized NNs, one can achieve almost zero training error on any data, even random labels, that yield massive test errors. So, how can we tell when such a model truly generalizes? arxiv.org/abs/2510.06028
arxiv.org
Generalization of Gibbs and Langevin Monte Carlo Algorithms in the Interpolation Regime
The paper provides data-dependent bounds on the test error of the Gibbs algorithm in the overparameterized interpolation regime, where low training errors are also obtained for impossible data, such a...
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Girish M. Duvvuri @gmduvvuri.bsky.social · 06/09/2026
The open secret to pedagogy research is that small class sizes/maximizing educator attention per pupil is the simplest, most effective, and unfortunately the least attractive to administration thing you can do to improve learning outcomes.
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H. P. Read @readhpr.bsky.social · 06/09/2026
Lovely article about a 99-year-old retired math professor who recently published a major result. It's the story of mentorship and multi-generational collaboration. www.nytimes.com/2026/09/06/s...
nytimes.com
The 92-Year-Old Mathematician and the Teenage Apprentice (Gift Article)
Joan Birman thought her major discoveries were behind her. Then came an email from a young neighbor — a girl who knew little but wanted to learn.
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Dom Williamson @domwilliamson.bsky.social · 04/09/2026
Fractons are immobile quasiparticles in topological phases of matter. In new work, led by Juliette Soule, we generalize fractons to spacetime. This leads to new dynamical quantum phases of matter and floquet codes with no stringlike logical faults in space or time. arxiv.org/abs/2609.03703
Fractons hopping in space (left) and spacetime (right)
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Marius Lemm @mariuslemm.bsky.social · 15/10/2025
Are the dynamics of disordered quantum many-body systems easier to simulate? --> Yes, because entanglement spreads slowly for a non-perturbatively long time (a.k.a. "prethermal MBL"). This is true in any dimension. arxiv.org/pdf/2510.11831 Thanks to my collaborators Ben McDonough and Andy Lucas!
arxiv.org
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cafkafk @cafkafk.bsky.social · 03/09/2026
also, rsa-260 is broken now, last was rsa-250 in Apr 2020
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Mark Riedl @markriedl.bsky.social · 30/08/2026
Majoring in CS used to mean a decent job (might still). CS was never meant to be about just programming. CS departments let students think that anyway because money. CS enrollments are dropping. That might be a good thing* (disclosure: I’m a CS professor). Here’s one way things might unfold…
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Mark M. Wilde @markwilde.bsky.social · 29/08/2026
New paper: Conditional contraction coefficients and their applications to quantum networks arxiv.org/abs/2608.27171 Joint work with @christophhirche.bsky.social , Ian George, and Theshani Nuradha Motivating question: How much information does a noisy quantum channel destroy?
arxiv.org
Conditional contraction coefficients and their applications to quantum networks
Contraction coefficients quantify the loss of distinguishability induced by a channel and provide a strong form of the data-processing inequality. While standard contraction coefficients ignore auxili...
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Gemma De les Coves @gemmadlc.bsky.social · 27/08/2026
The view from within can differ from the view from without. An observer, which is a physical system itself, may experience limitations to what it can learn similar to those in Quantum Theory, even in a deterministic theory. New work with J. Fankhauser & T. Gonda arxiv.org/abs/2608.258...
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Gautam Kamath @gautamkamath.com · 18/08/2026
Obviously this doesn't scale, but I chose to send this junior researcher a (hopefully polite) email with some of my thoughts (written hastily in 30 minutes, not polished). More practicing mathematicians & researchers should advocate for the culture they want, so here's my bit.
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Alexander Jahn @physicistalex.bsky.social · 12/08/2026
Three years ago, we proposed "overlapping qubits" as a description of information encoding in quantum gravity. In our new paper with Charles Cao's group at @virginiatech.bsky.social, we finally apply overlapping qubits to evaporating black holes! arxiv.org/abs/2608.10085
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Mark Riedl @markriedl.bsky.social · 11/08/2026
Claude is getting watermarks. I presume GPT will need to implement this too to comply with EU regulations support.claude.com/en/articles/...
support.claude.com
How Claude marks AI-generated content | Claude Help Center
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Petra Schwer @petraschwer.bsky.social · 10/08/2026
Like many others I was feeling the lack of a platform where the full spectrum of opinions (in particular also lesser heard voices) on "math and AI" may get an audience. Now here it is! Think about contributing and share it widely! proofsandprompts.com #math #mathsky #llm #AI #mathandai
proofsandprompts.com
Proofs and Prompts
Notes from the common room
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Gautam Kamath @gautamkamath.com · 10/08/2026
I'm pleased to share our #ICML2026 tutorial on machine unlearning! Presented by Vinith Suriyakumar and myself, it includes a full set of videos recorded and posted to YouTube! Please check it out: unlearning-tutorial.github.io
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🇵🇸Tim Henke (tɪm 'ɦɛŋ.kə) @timhenke.bsky.social · 08/08/2026
In summary, it seems like two of the biggest results in their big list of 10 was just putting two things together and not citing them properly paywall-free link: www.yahoo.com/news/science...
yahoo.com
OpenAI’s latest math breakthroughs commit research misconduct, experts say
OpenAI’s newest chatbot may be a whiz at math, but it seems to be lagging far behind humans in its academic rigor. Last week the company announced 10 more artificial-intelligence-generated math advan...
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William Umboh @swumboh.bsky.social · 07/08/2026
Exactly how i feel about writing myself semi-rad.com/2026/08/do-i...
semi-rad.com
Do It 14,000 Times Slower With This One Trick – Semi-Rad.com
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Dave Bacon @dabacon.tachyon.institute · 06/08/2026
Unverified but BIG if true eprint.iacr.org/2026/1591
eprint.iacr.org
A Polynomial-Time Quantum Algorithm for the Dihedral Coset Problem
We present a polynomial-time quantum algorithm for the Dihedral Coset Problem (DCP). The algorithm is based on Regev's polynomial-time reduction of the Dihedral Subgroup Problem (DSP) to the modular ...
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Henry Yuen @henryyuen.bsky.social · 01/08/2026
Some initial thoughts, and a complicated mix of feelings. Wow. I mean, Erdos problems are cool (I genuinely mean that), I didn't know about the Jacobian conjecture before it got disproved. But this newest batch from OpenAI hits home in a way the previous announcements did not.
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Alexander Stottmeister @stotti-alex.bsky.social · 28/07/2026
I tend to agree with Tobias. It will be interesting to see near-term changes in the valuation of certain aspects of research. An important problem I see is who can afford access to frontier models and how the scientific community should address this. tjoresearchnotes.wordpress.com/2026/07/28/p...
tjoresearchnotes.wordpress.com
Proof inflation
I have been thinking a lot about how social dynamics are going to shift in the new era of cognitive abundance. I don’t pretend to have any kind of crystal ball, but there are numerous histori…
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Greg Egan @gregegansf.bsky.social · 27/07/2026
While the Fields Medal celebrates the under-40s, the mathematician Joan Birman has, at the age of 99, solved a major open problem in representations of the Braid groups, a topic she has worked on for more than 60 years.
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siddhant @siddhantm.bsky.social · 19/07/2026
Belief propagation is reshaping how we think about tensor networks, and now it can be improved systematically. Check it out! “PEPS is hard” may be becoming less absolute. Using these techniques in practice? I’d love to hear what works, what doesn’t, and where they break down.
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Peter Coles 🏳️‍🌈 🏳️‍⚧️ 🇮🇪 @telescoper.bsky.social · 14/07/2026
The Coherence Principle Back into the swing of things in Maynooth, getting ready for the repeat examinations that start next month, I realized that I had forgotten to pass on an interesting paper that I found out about a few weeks ago but was reminded of while in London so I'm remedying my…
telescoper.blog
The Coherence Principle
Back into the swing of things in Maynooth, getting ready for the repeat examinations that start next month, I realized that I had forgotten to pass on an interesting paper that I found out about a few weeks ago but was reminded of while in London so I'm remedying my omission now. The title is The Coherence Principle: A Falsifiable Prior for Model Selection from the Grammar of Theories…
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Andrew Gordon Wilson @andrewgwils.bsky.social · 14/07/2026
How far can we compress billion-parameter LLMs? We introduce requential coding, which achieves < 1-bit per param compression, and explains why scaling doesn't hit a generalization wall! arxiv.org/pdf/2607.11883 w/ Shikai Qiu, Marc Finzi, Yujia Zheng, Kun Zhang 1/🧵
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cyber professional @permadeath.com · 13/07/2026
new favorite diagram shortlist entry
graph showing relationships between probability distributions, including cases of special parameters and convergence.  the normal distribution is quite central
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Ben Brubaker @benbenbrubaker.bsky.social · 06/07/2026
After 20 years, researchers finally have strong evidence that “quantum proofs” are more powerful than ordinary classical ones. The results suggest that at least in computation, there’s no way around the complexity of the quantum world. Read more in @quantamagazine.bsky.social:
quantamagazine.org
Researchers Reveal the Power of ‘Quantum Proofs’ | Quanta Magazine
When checking that solutions to certain problems are correct, it turns out, you can’t get around the inherent complexity of the quantum world.
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Andreas Bluhm @hippoquantus.bsky.social · 26/06/2026
I am happy to announce that our newest work on non-local quantum computation (NLQC) has made it to the arXiv: scirate.com/arxiv/2606.2.... For me personally, the main motivation to study these tasks comes from quantum position verification, but it has links to diverse areas such as quantum gravity.
scirate.com
Equivalence of non-local computation tasks beyond Clifford operations
Non-local quantum computation (NLQC) studies how two collaborating players can implement channels on distributed systems using a single simultaneous round of quantum communication and shared entanglem...
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Rafael Macêdo @rafammacedo.bsky.social · 22/06/2026
Thanks Ernesto!! 😊
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Rafael Macêdo @rafammacedo.bsky.social · 22/06/2026
a bit late, but as of this month, I’ve joined QMATH @qmath-copenhagen.bsky.social as a postdoc in @dansfranca.bsky.social 's group! i'll be working on quantum algorithms theory and quantum info more broadly. if anyone in the copenhagen area wants to collaborate, hit me up!
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Peter Coles 🏳️‍🌈 🏳️‍⚧️ 🇮🇪 @telescoper.bsky.social · 17/06/2026
Bayesian Inductive Inference and the Anthropic Cosmological Principle Many moons ago I wrote a paper with a person called Antony J.M. Garrett with the title Bayesian Inductive Inference and the Anthropic Cosmological Principle (the full reference is A.J.M. Garrett and P. Coles, Comments on…
telescoper.blog
Bayesian Inductive Inference and the Anthropic Cosmological Principle
Many moons ago I wrote a paper with a person called Antony J.M. Garrett with the title Bayesian Inductive Inference and the Anthropic Cosmological Principle (the full reference is A.J.M. Garrett and P. Coles, Comments on Astrophysics 17(1) 23-47 (1993). It got a few citations here and there, and has been discussed in a few books and other texts. In 1999, the journal&hellip;
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Gabriel Peyré @gabrielpeyre.bsky.social · 16/06/2026
The alpha version of my new book "Optimal Transport for Machine Learners" is out, with in particular an online version with interactive figures www.gpeyre.com/ot4ml/
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Nahuel L Diaz @nahuelldiaz.bsky.social · 13/06/2026
I'm so happy to share this paper, we put a lot into this one: arxiv.org/abs/2606.12539 If you have ever wondered what the quantum-information literature has to say about temporal correlations and time itself, check out our unifying picture: all you need are spacetime states.
arxiv.org
Unifying spacetime approaches to quantum mechanics
Recent efforts to formulate quantum mechanics in a way that treats space and time on a more equal footing have led to a large variety of spacetime-oriented approaches. In this work we present a detail...
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