Jens Eisert @jenseisert.bsky.social · 04/10/2026This is a question that has been sitting around for more than a decade: how can we optimally test whether a given quantum state is Gaussian or not? We provide an optimal answer here. scirate.com/arxiv/2609.4... 070
Jens Eisert @jenseisert.bsky.social · 04/10/2026Adaptivity is all you need: Stabilizer states can be optimally learned using just single-copy measurements and adaptivity. scirate.com/arxiv/2610.0... 030
Jens Eisert @jenseisert.bsky.social · 04/10/2026Some of the fun in quantum information science comes from connecting technology with fundamental physics. Tools developed to control and measure quantum systems can also give us new ways to probe the symmetries of nature. Our new work explores such a connection. scirate.com/arxiv/2610.0... 041
Jens Eisert @jenseisert.bsky.social · 04/10/2026A provable quantum advantage for approximate optimization via decoded quantum interferometry in a meaningful oracle setting, showing a separation in approximation ratios for folded folded optimal polynomial intersection. scirate.com/arxiv/2610.0... 070
Jens Eisert @jenseisert.bsky.social · 30/09/2026Warm thanks to @ludovicolami.bsky.social, Lorenzo Leone and Jacopo Rizzo. 000
Jens Eisert @jenseisert.bsky.social · 30/09/2026Quantum coding schemes typically rely on knowing the underlying state or channel. In “Universal quantum coding,” we show how to distil entanglement and communicate quantum information without this prior knowledge. scirate.com/arxiv/2609.3... 131
Jens Eisert @jenseisert.bsky.social · 30/09/2026In our new work, “Ultra-high-distance quantum memories from amplified #qLDPC codes,” we introduce distance amplifiers: a modular way to increase both code distance and certified protection against circuit faults. The key is a rigorous fault-response certificate. scirate.com/arxiv/2609.3... 030
Jens Eisert @jenseisert.bsky.social · 04/09/2026Thanks to Francesco Arzani and @timohillmann.bsky.social. 030
Jens Eisert @jenseisert.bsky.social · 04/09/2026We codesign quantum error correcting codes and decoders in quantum low-density lattice codes. scirate.com/arxiv/2609.0... 181
Jens Eisert @jenseisert.bsky.social · 04/09/2026Does computational pseudorandomness require statistical randomness? Surprisingly, no. scirate.com/arxiv/2609.0... 020
Jens Eisert @jenseisert.bsky.social · 28/08/2026I am happy to see this paper out. And warm thanks to Simon Cichy, Paul K. Faehrmann, Lennart Bittel and Hakop Pashyan for the wonderful collaboration. 000
Jens Eisert @jenseisert.bsky.social · 28/08/2026How far can noise “dequantize” quantum circuits? We introduce a highly parallelizable tensor-network algorithm that optimally unravels arbitrary single-qubit noise to minimize entanglement, with rigorous simulation-error guarantees. journals.aps.org/pra/abstract... 160
Jens Eisert @jenseisert.bsky.social · 14/08/2026Random quantum circuits are a central tool in quantum information and many-body physics. But how random should the individual gates actually be? Perhaps surprisingly: less random local gates can generate more global randomness. journals.aps.org/pra/abstract... 040
Reposted by Jens EisertGreg White @gregswhitenoise.bsky.social · 16/07/2026My 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...docs.google.comWhat 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... 063
Jens Eisert @jenseisert.bsky.social · 01/08/2026Dynamical 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... 051
Jens Eisert @jenseisert.bsky.social · 31/07/2026Quantum 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... 030
Jens Eisert @jenseisert.bsky.social · 30/07/2026We review recent progress in using machine learning, deep learning and language models to represent, characterize, certify and benchmark quantum systems. 020
Jens Eisert @jenseisert.bsky.social · 30/07/2026I 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... 163
Jens Eisert @jenseisert.bsky.social · 24/07/2026That is another @mathplusberlin.bsky.social like paper. 000
Jens Eisert @jenseisert.bsky.social · 24/07/2026Complete 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. 181
Jens Eisert @jenseisert.bsky.social · 27/06/2026This is in principle a @mathplusberlin.bsky.social like topic. 020
Jens Eisert @jenseisert.bsky.social · 27/06/2026Rigorous 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... 230
Jens Eisert @jenseisert.bsky.social · 19/06/2026Congrats, Georgia. And nice to see our papers back to back that, hopefully, will make an impact on how people think about quantum error correction for superconducting hardware. See you soon in Berlin. 020
Jens Eisert @jenseisert.bsky.social · 19/06/2026Thank you, David. And, as you know and as we generously give credit for, it strongly builds on your beautiful work. Please come round soon. 020
Jens Eisert @jenseisert.bsky.social · 19/06/2026Experimental 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... 051
Jens Eisert @jenseisert.bsky.social · 19/06/2026Nearest-neighbour gates are all you need: High-rate quantum low-density parity-check codes on a planar grid. scirate.com/arxiv/2606.1... 1204
Jens Eisert @jenseisert.bsky.social · 27/05/2026What 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... 170
Jens Eisert @jenseisert.bsky.social · 08/05/2026For generating #pseudorandomness using doped #Clifford circuits, fundamental bounds on the resource cost show that extensive doping levels are necessary. go.aps.org/3RjBHQP 040
Jens Eisert @jenseisert.bsky.social · 05/05/2026I am not sure I fully agree. It has certainly not replaced the old Twitter, but in some ways, X still appears more engaging than Bluesky. 200
Jens Eisert @jenseisert.bsky.social · 05/05/2026That sounds exciting and wonderful. But why are you tagging me in this? 010
Jens Eisert @jenseisert.bsky.social · 05/05/2026I 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? 210
Jens Eisert @jenseisert.bsky.social · 13/04/2026The 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... 0141
Jens Eisert @jenseisert.bsky.social · 03/04/2026Warm thanks to Julio C. Magdalena de la Fuente, Noa Feldman, and Andreas Bauer. 010
Jens Eisert @jenseisert.bsky.social · 03/04/2026We 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... 1110
Jens Eisert @jenseisert.bsky.social · 02/04/2026In the absence of quantum error correction, circuits of #quantumcomputers can be logarithmically deep. www.nature.com/articles/s41... 082
Jens Eisert @jenseisert.bsky.social · 28/03/2026But this is a good point: We will add a comment to this effect. 020
Reposted by Jens EisertJoschka Roffe @qec.codes · 06/03/2026📢 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...scirate.comQGPU: Parallel logic in quantum LDPC codesQuantum 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... 1201
Reposted by Jens EisertElies Gil-Fuster @eliesgf.bsky.social · 25/03/2026New #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.socialarxiv.orgA PAC-Bayesian approach to generalization for quantum modelsGeneralization 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... 1113
Jens Eisert @jenseisert.bsky.social · 28/03/2026Measurement-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... 140
Jens Eisert @jenseisert.bsky.social · 28/03/2026What 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. 021
Jens Eisert @jenseisert.bsky.social · 06/03/2026QGPU: 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. 0100