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Zoltán Zimborás

@zoltanzimboras.bsky.social
573 followers 492 following 38 posts

Wigner's friend. Coincidentally also the Head of the Quantum Computing Group at Wigner RCP. Occasionally hired for the indirect observation of measurements.

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Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026
This was a super fun work with done jointly with Jiwon Heo, Changhun Oh, Oliver Reardon-Smith, and Michal Oszmaniec. A great joint collaboration between KAIST, CTP PAS Warsaw, and University of Helsinki.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026
Computing expectation values of Majorana strings of any weight with additive error scales as O(n³ε⁻² log(2/δ)). A naive extension can blow up; a sample-adapted Gaussian decomposition keeps the variance ≤ 1.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026
Computing the exact expectation values of weight-k Majorana strings cost O(n²+nk·2^k), so computing these for logarithmic weight is polynomial; while Majorana-propagation-style methods were quasi-polynomial. A dynamic program with auxiliary fermions tracks the signs.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026
The principle behind our sampler is to remove (or add) a particle, which gradually strips magic from the input; sample that easier problem recursively; recover the parent sample from a small set of jointly computed probabilities. Applied to bosons, it re-derives the Clifford–Clifford algorithm.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026
As the Table shows, the cost of the computation depends on the precise simulation task. For exact sampling with the input being an n-fold copy of 4-mode magic states, we provide a sample costs O(n⁴+2ⁿ) for passive and O(n⁵+2ⁿ) for active Gaussian dynamics, vs O(n⁵·2ⁿ) before.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026
In our new preprint (prepared in the current QIP rush), we ask: How hard is it to simulate free fermion dynamics with magic input states classically? The reply is condensed in the Table below. Paper: scirate.com/arxiv/2609.4... arxiv.org/abs/2609.40187 1/6
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Zoltán Zimborás @zoltanzimboras.bsky.social · 06/07/2026
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Zoltán Zimborás @zoltanzimboras.bsky.social · 13/03/2026
Today we close the week with a Gaussian Boson Sampling model that we can train with hundreds of photonic modes and more than a million trainable parameters using a single GPU. arxiv.org/abs/2603.11195 3/3
arxiv.org
Generative modeling with Gaussian Boson Sampling: classically trainable Bosonic Born Machines
Quantum generative modeling has emerged as a promising application of quantum computers, aiming to model complex probability distributions beyond the reach of classical methods. In practice, however, ...
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Zoltán Zimborás @zoltanzimboras.bsky.social · 13/03/2026
On Wednesday, colleagues from Quandela put out a paper on how to do efficient classical training of Fock-state Boson Sampling. arxiv.org/abs/2603.08793 Yesterday, we put out similar results complementing it with universality guarantees and connections to hardness. arxiv.org/abs/2603.11014 2/3
arxiv.org
Universality of Classically Trainable, Quantum-Deployed Boson-Sampling Generative Models
Recent work on the instantaneous quantum polynomial-time (IQP) quantum-circuit Born machine (QCBM) highlights a promising paradigm for generative modeling: train classically, deploy quantumly. In this...
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Zoltán Zimborás @zoltanzimboras.bsky.social · 13/03/2026
This week scalable quantum generative learning finally reached bosonic systems: scirate.com/arxiv/2603.1... 1/3
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Zoltán Zimborás @zoltanzimboras.bsky.social · 13/03/2026
Wow! I also strongly hope that it stays nonprofit...
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Zoltán Zimborás @zoltanzimboras.bsky.social · 09/01/2026
Great thread by Stefan Knecht on the new paper by the Garnet Chan group: "FeMoCo hasn’t been entirely solved, but for its gold-standard active space model (which is the model QC folks have been looking at!), there is now a classical benchmark that provides an excellent baseline for any quantum work"
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Zoltán Zimborás @zoltanzimboras.bsky.social · 26/11/2025
A larger update of our Majorana propagation paper is out! arxiv.org/abs/2503.18939
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Zoltán Zimborás @zoltanzimboras.bsky.social · 26/11/2025
Great! Huge congrats!
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Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025
With Bence and Zoli, we were able to train Fermionic Born Machine circuits even in the range of 120–160 qubits quite easily, but stay tuned for further improvements to our training methods, where we aim beyond 1000 qubits… 6/6
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Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025
Our model builds on previous work on the hardness of Fermion Sampling (fermionic magic states + fermionic linear optics) with @michaloszmaniec.bsky.social (Michal Oszmaniec), Mauro Morales, and Ninnat Dangniam 5/6 journals.aps.org/prxquantum/a...
journals.aps.org
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Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025
Together with my two fantastic PhD students, Bence Bakó and Zoltán Kolarovszki, we now introduce a second compelling quantum generative model that is also (potentially) hard to sample from classically, yet can be trained classically. 4/6
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Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025
In that they show that generative models based on IQP circuits can be trained efficiently on classical hardware, while classical sampling remains hard - offering a potential computational advantage and at the same time resolving issues related to quantum gradient estimation. 3/6
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Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025
A related generative QML work that really impressed me this year was by Joseph Bowles, Erik Recio-Armengol, and Shahnawaz Ahmed 2/6 arxiv.org/abs/2503.02934
arxiv.org
Train on classical, deploy on quantum: scaling generative quantum machine learning to a thousand qubits
We propose an approach to generative quantum machine learning that overcomes the fundamental scaling issues of variational quantum circuits. The core idea is to use a class of generative models based ...
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Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025
Happy to see that our paper on the classical training and quantum inference of Fermionic Born Machines is now out on arXiv! 1/6 scirate.com/arxiv/2511.1...
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Zoltán Zimborás @zoltanzimboras.bsky.social · 08/11/2025
Super happy to see that our paper on the "Quantum generalizations of Glauber and Metropolis dynamics" with Anthony Chen, Csaba Czabán, João Doriguello, András Gilyén, Balázs Kabella, Michael Kastoryano, József Mák was accepted as a talk at #QIP2026 🎉🎉🎉
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Zoltán Zimborás @zoltanzimboras.bsky.social · 30/08/2025
Thanks a lot for visiting, Alex (@physicistalex.bsky.social)! It was super nice and productive - we found a couple of nice platonic ideas concerning hyperbolic tilings and spin models.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 01/07/2025
See See also the great parallel work by M. West, D. García-Martín, N.L. Diaz, @mvscerezo.bsky.social, and @martinlaroo.bsky.social: scirate.com/arxiv/2506.1...
scirate.com
No-go theorems for sublinear-depth group designs
Constructing ensembles of circuits which efficiently approximate the Haar measure over various groups is a long-standing and fundamental problem in quantum information theory. Recently it was shown th...
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Zoltán Zimborás @zoltanzimboras.bsky.social · 01/07/2025
The paper was a result of a wonderful collaboration with Lorenzo Grevink, @haferjonas.bsky.social , @markusheinrich.bsky.social, Jonas Helsen, Marcel Hinsche, Tommy Schuster that started during a discussion at the Random Quantum Circuits in Amsterdam.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 01/07/2025
In our new paper, we derive linear lower bounds on the circuit depth of Clifford, orthogonal, symplectic, matchgate designs (built of local gates from the respective groups).
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Reposted by Zoltán Zimborás
Deyan Ginev @dginev.bsky.social · 11/06/2025
This is not the way for HTML papers to gain visibility, but it's a kind of fallback I suppose. Last day's PDFs should be gradually coming back online, apologies for the delay.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 11/06/2025
Yes, at least the HTML papers got visibility 😀. Btw, the pdfs were in deed back in the afternoon. Thx, for reacting fast!
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Zoltán Zimborás @zoltanzimboras.bsky.social · 11/06/2025
ArXiv seems broken this morning, can't get the pdf of today's papers. (Btw, the html option still works, so one can access the papers in that form.) @arxiv-quant-ph.bsky.social
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Zoltán Zimborás @zoltanzimboras.bsky.social · 25/03/2025
Our new Majorana Propagation method is out! It can be used either alone as a classical simulation method or in conjunction with quantum subroutines, see @qzoeholmes.bsky.social's thread below. (Btw, it's so efficient that it broke scirate: this and all papers after ours are missing from scirate.)
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Zoltán Zimborás @zoltanzimboras.bsky.social · 21/02/2025
Happy to share that I will join University of Helsinki as a Professor at the Department of Physics. The team at UH has been incredibly welcoming, and I’m looking forward to working here. More to come soon (e.g., announcements of open postdoc, PhD positions)!
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Zoltán Zimborás @zoltanzimboras.bsky.social · 11/02/2025
Wow! Wonder how what Google map shows in Mexico....
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Zoltán Zimborás @zoltanzimboras.bsky.social · 11/02/2025
That was fast! Today on my Google Map:
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Zoltán Zimborás @zoltanzimboras.bsky.social · 09/02/2025
I use my quantum crystals every morning
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Zoltán Zimborás @zoltanzimboras.bsky.social · 09/02/2025
Recently, I was rereading Carl Sagan’s book, "The Demon-Haunted World: Science as a Candle in the Dark" published in 1995. I am just now randomly posting a paragraph from it; you know, any resemblance to actual events is purely coincidental.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 06/02/2025
The central idea of our work is that the difficulty of counting degrees of freedom in quantum gravity has a nice quantum info analogue: Verifying the size of a Hilbert space with qubit operations ("overlapping qubits problem") . Stay tuned for further works on this!
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Zoltán Zimborás @zoltanzimboras.bsky.social · 06/02/2025
I am super happy that this work is out now in Nature Communications! It was really fun to work and discuss with Charles ChunJun Cao, Wissam Chemissany and Alexander Jahn! www.nature.com/articles/s41...
nature.com
Overlapping qubits from non-isometric maps and de Sitter tensor networks - Nature Communications
For some states in quantum gravity, notions of locality can deviate from effective field theory predictions. Here, the authors show that such deviations can be recast in the quantum information framew...
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Reposted by Zoltán Zimborás
Victor V. Albert @vva.bsky.social · 14/01/2025
"We do not yet have proven exponential quantum speedups for end-to-end applications in machine learning, optimization, quantum chemistry, or materials science that guarantee substantial commercial and financial value." arxiv.org/pdf/2501.05694
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Reposted by Zoltán Zimborás
John Preskill @preskill.bsky.social · 14/01/2025
Useful perspective, clearly written and well-reasoned. arxiv.org/abs/2501.05694
arxiv.org
Myths around quantum computation before full fault tolerance: What no-go theorems rule out and what they don't
In this perspective article, we revisit and critically evaluate prevailing viewpoints on the capabilities and limitations of near-term quantum computing and its potential transition toward fully fault...
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Zoltán Zimborás @zoltanzimboras.bsky.social · 13/01/2025
Great experiment! Let us see whether meme people are willing to use latex/tikzpic (even if they are of the simplest form) instead of the usual "write your text here" meme apps. Btw, I like the color change.
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Zoltán Zimborás @zoltanzimboras.bsky.social · 13/01/2025
Funny suggestion 😀. Actually, these meters were made with a short tikzpicture code that one can find directly in the paper's latex source (one just has to enter a number indicating the angle of the meter).
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Zoltán Zimborás @zoltanzimboras.bsky.social · 13/01/2025
To reach some consensus about the prospects of near-term (late nisq and early fault tolerant) quantum computing, we had a 3-day discussion event (“Quantum Now”) in Lapland with both optimists and pessimists. This continued at SeeQA 2024 in Oxford. See our conclusions here arxiv.org/abs/2501.05694
arxiv.org
Myths around quantum computation before full fault tolerance: What no-go theorems rule out and what they don't
In this perspective article, we revisit and critically evaluate prevailing viewpoints on the capabilities and limitations of near-term quantum computing and its potential transition toward fully fault...
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