Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026This 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. 010
Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026Computing 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. 100
Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026Computing 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. 100
Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026The 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. 100
Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026As 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. 100
Zoltán Zimborás @zoltanzimboras.bsky.social · 01/10/2026In 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 1/6 190
Zoltán Zimborás @zoltanzimboras.bsky.social · 13/03/2026Today 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 3/3arxiv.orgGenerative modeling with Gaussian Boson Sampling: classically trainable Bosonic Born MachinesQuantum 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, ... 031
Zoltán Zimborás @zoltanzimboras.bsky.social · 13/03/2026On 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 2/3arxiv.orgUniversality of Classically Trainable, Quantum-Deployed Boson-Sampling Generative ModelsRecent 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... 120
Zoltán Zimborás @zoltanzimboras.bsky.social · 13/03/2026This week scalable quantum generative learning finally reached bosonic systems: scirate.com/arxiv/2603.1... 1/3 140
Zoltán Zimborás @zoltanzimboras.bsky.social · 13/03/2026Wow! I also strongly hope that it stays nonprofit... 110
Zoltán Zimborás @zoltanzimboras.bsky.social · 09/01/2026Great 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" 071
Zoltán Zimborás @zoltanzimboras.bsky.social · 26/11/2025A larger update of our Majorana propagation paper is out! arxiv.org/abs/2503.18939 050
Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025With 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… 6/6 010
Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025Our 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 130
Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025Together 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. 4/6 110
Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025In 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. 3/6 110
Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025A 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/2503.02934arxiv.orgTrain on classical, deploy on quantum: scaling generative quantum machine learning to a thousand qubitsWe 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 ... 100
Zoltán Zimborás @zoltanzimboras.bsky.social · 19/11/2025Happy 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... 1120
Zoltán Zimborás @zoltanzimboras.bsky.social · 08/11/2025Super 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 🎉🎉🎉 0100
Zoltán Zimborás @zoltanzimboras.bsky.social · 30/08/2025Thanks 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. 160
Zoltán Zimborás @zoltanzimboras.bsky.social · 01/07/2025See 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.comNo-go theorems for sublinear-depth group designsConstructing 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... 010
Zoltán Zimborás @zoltanzimboras.bsky.social · 01/07/2025The 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. 160
Zoltán Zimborás @zoltanzimboras.bsky.social · 01/07/2025In 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). 090
Reposted by Zoltán ZimborásDeyan Ginev @dginev.bsky.social · 11/06/2025This 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. 141
Zoltán Zimborás @zoltanzimboras.bsky.social · 11/06/2025Yes, at least the HTML papers got visibility 😀. Btw, the pdfs were in deed back in the afternoon. Thx, for reacting fast! 010
Zoltán Zimborás @zoltanzimboras.bsky.social · 11/06/2025ArXiv 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 050
Zoltán Zimborás @zoltanzimboras.bsky.social · 25/03/2025Our 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.) 0151
Zoltán Zimborás @zoltanzimboras.bsky.social · 21/02/2025Happy 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)! 6390
Zoltán Zimborás @zoltanzimboras.bsky.social · 11/02/2025Wow! Wonder how what Google map shows in Mexico.... 130
Zoltán Zimborás @zoltanzimboras.bsky.social · 09/02/2025Recently, 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. 1112
Zoltán Zimborás @zoltanzimboras.bsky.social · 06/02/2025The 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! 040
Zoltán Zimborás @zoltanzimboras.bsky.social · 06/02/2025I 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.comOverlapping qubits from non-isometric maps and de Sitter tensor networks - Nature CommunicationsFor 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... 1100
Reposted by Zoltán ZimborásVictor 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 0292
Reposted by Zoltán ZimborásJohn Preskill @preskill.bsky.social · 14/01/2025Useful perspective, clearly written and well-reasoned. arxiv.org/abs/2501.05694arxiv.orgMyths around quantum computation before full fault tolerance: What no-go theorems rule out and what they don'tIn 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... 16515
Zoltán Zimborás @zoltanzimboras.bsky.social · 13/01/2025Great 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. 130
Zoltán Zimborás @zoltanzimboras.bsky.social · 13/01/2025Funny 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). 150
Zoltán Zimborás @zoltanzimboras.bsky.social · 13/01/2025To 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/2501.05694arxiv.orgMyths around quantum computation before full fault tolerance: What no-go theorems rule out and what they don'tIn 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... 15212