My good friend and famed lover of questionnaires @eliesgf.bsky.social has a simple question for the quantum info community: what do you think when you hear the terms "strong" and "weak simulation? He (and by extension, me) would love it if you filled in this Google Form! forms.gle/wfFcwBPdaafv...

What does it mean to simulate a quantum computation?

Dear colleagues, We are some quantum researchers at FU Berlin. We were recently surprised among ourselves that we used the same words in very different incompatible ways when it comes to classically...

docs.google.com

Dynamical codes for hardware with noisy readouts We investigate the performance of dynamical stabilizer codes when measurements are noisy, as expected in many quantum computing platforms, with surprising outcomes. quantum-journal.org/papers/q-202...

Quantum computers offer #quantumadvantage for combinatorial #optimization, but the practical advantage remains to be quantified. We study decoded quantum interferometry and show that classical sampling can closely emulate its performance across numerical benchmarks. scirate.com/arxiv/2607.2...

I am delighted to see that our review "Artificial intelligence for representing and characterizing quantum systems" is now published in Nature Reviews Physics. www.nature.com/articles/s42...

Complete theory of the Clifford commutant quantum-journal.org/papers/q-202... The Clifford group is central to quantum information. We develop a complete theory of its commutant, with explicit bases, dimension formulas, and a graphical calculus - and show a wealth of applications.

Rigorous no-go theorems for heralded linear-optical state generation tasks: Algebraic geometry in applied mathematics meets design choices in linear optical state preparation for photonic quantum computing. journals.aps.org/pra/abstract...

Experimental measurement and a physical interpretation of quantum shadow enumerators We show that Rains' quantum shadow enumerators - a powerful tool from #quantumerrorcorrection - admit a direct physical interpretation in terms of two-copy Bell measurements. journals.aps.org/prresearch/a...

Nearest-neighbour gates are all you need: High-rate quantum low-density parity-check codes on a planar grid. scirate.com/arxiv/2606.1...

What role do #measurements play in quantum algorithms? We systematically explore this question in the context of a greatly simplified #quantumalgorithm for the abelian hidden subgroup problem for states (#StateHSP), featuring a reduced circuit complexity. journals.aps.org/prxquantum/a...

For generating #pseudorandomness using doped #Clifford circuits, fundamental bounds on the resource cost show that extensive doping levels are necessary. go.aps.org/3RjBHQP

I generally keep politics out of my social media—that is a space better suited to others. But what is happening here? I primarily use Bluesky to share scientific content, and I still find X reasonably functional for that purpose. Yet there seem to be significant shifts underway. What is going on?

The term has started again at Freie Universität Berlin. This term, I am teaching my favourite subject, quantum information and quantum technologies. www.physik.fu-berlin.de/en/einrichtu...

We introduce a method for achieving high-threshold decoding of non-Pauli codes aimed at two-dimensional universality. Our results suggest that genuinely non-Clifford quantum operations in two-dimensional codes can perform comparably to those of a simple quantum memory. scirate.com/arxiv/2604.0...

In the absence of quantum error correction, circuits of #quantumcomputers can be logarithmically deep. www.nature.com/articles/s41...

📢 New paper. 𝐐𝐆𝐏𝐔: 𝐏𝐚𝐫𝐚𝐥𝐥𝐞𝐥 𝐥𝐨𝐠𝐢𝐜 𝐢𝐧 𝐪𝐮𝐚𝐧𝐭𝐮𝐦 𝐋𝐃𝐏𝐂 𝐜𝐨𝐝𝐞𝐬. A great collaboration w/ Boren Gu, Andi Lui, Armanda Quintavalle, Xian Xu, & @jenseisert.bsky.social 𝐭𝐥𝐝𝐫; Quantum LDPC codes are an exciting architecture for fault-tolerant ... 1/n scirate.com/arxiv/2603.0...

QGPU: Parallel logic in quantum LDPC codes

Quantum error correction is critical to the design and manufacture of scalable quantum computing systems. Recently, there has been growing interest in quantum low-density parity-check codes as a resou...

scirate.com

New #QML paper alert! 📝🧠⚛️ 🧐 A PAC-Bayesian approach to generalization for quantum models arxiv.org/abs/2603.22964 This collaboration involved some seriously hard and fun work by @pablones8.bsky.social, Matthias Caro, Carlos Bravo-Prieto, @fjschreiber.bsky.social, and @jenseisert.bsky.social

A PAC-Bayesian approach to generalization for quantum models

Generalization is a central concept in machine learning theory, yet for quantum models, it is predominantly analyzed through uniform bounds that depend on a model's overall capacity rather than the sp...

arxiv.org

Measurement-induced non-commutativity in adaptive fermionic linear optics We show that mid-circuit measurements of fermions with internal degrees of freedom can induce the equivalent of "magic" to free fermionic circuits and render them classically hard to sample. scirate.com/arxiv/2603.2...

What a week. A highlight for me has been the #quantumtechnologies segment of the Grand Challenges conference of the @berlinualliance.bsky.social. Jerry Chow blew everybody away with his talk.

QGPU: Parallel logic in quantum LDPC codes scirate.com/arxiv/2603.0... We introduce #clusteredcycliccodes for #quantumerrorcorrection and show how to pursue highly parallelized surface-code style quantum logic with quantum low density parity check codes featuring simple logicals.

Tight inapproximability of max-LINSAT and implications for decoded quantum interferometry. scirate.com/arxiv/2603.0... Warm thanks to @mxkramer.bsky.social and Carsten Schubert for this collaboration.

The unbearable hardness of deciding about magic We show that determining membership in the stabilizer polytope, which defines the free states of magic-state resource theory, requires super-exponential time exp(n2) in the number of qubits n, even approximately. scirate.com/arxiv/2602.2...

There are interesting separations in quantum learning theory depending on whether or not one has access to post-measurement states in quantum measurement. scirate.com/arxiv/2602.2...

Mid-circuit measurements are a powerful tool for state preparation. In contrast, their usefulness for #quantumcomputation remains comparatively less well understood. We demonstrate that #midcircuitmeasurementscan enable quantum advantages even in shallow circuits. journals.aps.org/prl/abstract...

Variational #quantumalgorithms and classical variational methods, such as #tensornetworks, provide upper bounds on ground-state energies. This work provides guarantees for lower bounds. journals.aps.org/pra/abstract...

We're excited to have kicked off a new project - together with Freie Universität Berlin, Technische Universität Berlin and NXP Semiconductors, and led by @jenseisert.bsky.social. Our goal is to advance the performance of quantum algorithms to solve real problems in semiconductor chip manufacturing.

ParityQC joins PraktiQOM project, developing advanced quantum algorithms for semiconductor chip design - ParityQC

ParityQC is a member of the PraktiQOM project, aiming to advance quantum algorithms to solve real-world optimization problems.

parityqc.com

This is a paper I very much like, for its foundational and somewhat "rebellious" character: We show that notions channel capacities are strongly altered if one simply assumes that all operations one can implement are efficient. scirate.com/arxiv/2601.1...

This is a paper I very much like, for its foundational and somewhat "rebellious" character: We show that notions channel capacities are strongly altered if one simply assumes that all operations one can implement are efficient. scirate.com/arxiv/2601.1...

It has been a great pleasure—and both fun and insightful—to speak with Dr. Thomas Ramge about the future of quantum technologies, broader aspects of science and technology, and what makes science so exciting in the first place. m.youtube.com/watch?si=mh2...

This is the most technological paper I have been involved in for a while. It presents a below-threshold error reduction in single photons through photon #distillation. scirate.com/arxiv/2601.0...

Variational optimization of projected entangled-pair states on the triangular lattice. journals.aps.org/prb/abstract... The “meta-message” is that the use of tools such as #automaticdifferentiation, and the co-design of the ansatz class and the physical system can improve #tensornetwork methods.