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Jens Eisert

@jenseisert.bsky.social
1.8K followers 1.1K following 301 posts

Scientist, professor of quantum physics at Freie Universität Berlin and affiliated with Helmholtz Center Berlin and the Fraunhofer Heinrich Hertz Institute. ERC Fellow.

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Jens Eisert @jenseisert.bsky.social · 04/10/2026
This 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...
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Jens Eisert @jenseisert.bsky.social · 04/10/2026
Adaptivity is all you need: Stabilizer states can be optimally learned using just single-copy measurements and adaptivity. scirate.com/arxiv/2610.0...
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Jens Eisert @jenseisert.bsky.social · 04/10/2026
Some 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...
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Jens Eisert @jenseisert.bsky.social · 04/10/2026
A 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...
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Jens Eisert @jenseisert.bsky.social · 30/09/2026
Thanks a lot! That has been great fun.
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Jens Eisert @jenseisert.bsky.social · 30/09/2026
Warm thanks to @ludovicolami.bsky.social, Lorenzo Leone and Jacopo Rizzo.
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Jens Eisert @jenseisert.bsky.social · 30/09/2026
Quantum 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...
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Jens Eisert @jenseisert.bsky.social · 30/09/2026
In 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...
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Jens Eisert @jenseisert.bsky.social · 04/09/2026
Thanks to Francesco Arzani and @timohillmann.bsky.social.
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Jens Eisert @jenseisert.bsky.social · 04/09/2026
We codesign quantum error correcting codes and decoders in quantum low-density lattice codes. scirate.com/arxiv/2609.0...
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Jens Eisert @jenseisert.bsky.social · 04/09/2026
Does computational pseudorandomness require statistical randomness? Surprisingly, no. scirate.com/arxiv/2609.0...
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Jens Eisert @jenseisert.bsky.social · 28/08/2026
I 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.
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Jens Eisert @jenseisert.bsky.social · 28/08/2026
How 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...
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Jens Eisert @jenseisert.bsky.social · 14/08/2026
Random 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...
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Reposted by Jens Eisert
Greg White @gregswhitenoise.bsky.social · 16/07/2026
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...
docs.google.com
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...
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Jens Eisert @jenseisert.bsky.social · 01/08/2026
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...
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Jens Eisert @jenseisert.bsky.social · 31/07/2026
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...
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Jens Eisert @jenseisert.bsky.social · 30/07/2026
We review recent progress in using machine learning, deep learning and language models to represent, characterize, certify and benchmark quantum systems.
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Jens Eisert @jenseisert.bsky.social · 30/07/2026
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...
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Jens Eisert @jenseisert.bsky.social · 24/07/2026
That is another @mathplusberlin.bsky.social like paper.
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Jens Eisert @jenseisert.bsky.social · 24/07/2026
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.
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Jens Eisert @jenseisert.bsky.social · 27/06/2026
This is in principle a @mathplusberlin.bsky.social like topic.
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Jens Eisert @jenseisert.bsky.social · 27/06/2026
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...
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Jens Eisert @jenseisert.bsky.social · 19/06/2026
Congrats, 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.
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Jens Eisert @jenseisert.bsky.social · 19/06/2026
Thank you, David. And, as you know and as we generously give credit for, it strongly builds on your beautiful work. Please come round soon.
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Jens Eisert @jenseisert.bsky.social · 19/06/2026
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...
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Jens Eisert @jenseisert.bsky.social · 19/06/2026
Thanks for posting.
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Jens Eisert @jenseisert.bsky.social · 19/06/2026
Nearest-neighbour gates are all you need: High-rate quantum low-density parity-check codes on a planar grid. scirate.com/arxiv/2606.1...
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Jens Eisert @jenseisert.bsky.social · 27/05/2026
CC #CRC183, @simontrebst.bsky.social.
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Jens Eisert @jenseisert.bsky.social · 27/05/2026
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...
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Jens Eisert @jenseisert.bsky.social · 08/05/2026
For generating #pseudorandomness using doped #Clifford circuits, fundamental bounds on the resource cost show that extensive doping levels are necessary. go.aps.org/3RjBHQP
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Jens Eisert @jenseisert.bsky.social · 05/05/2026
I 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.
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Jens Eisert @jenseisert.bsky.social · 05/05/2026
No, I cannot, that it why I am asking.
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Jens Eisert @jenseisert.bsky.social · 05/05/2026
That sounds exciting and wonderful. But why are you tagging me in this?
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Jens Eisert @jenseisert.bsky.social · 05/05/2026
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?
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Jens Eisert @jenseisert.bsky.social · 13/04/2026
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...
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Jens Eisert @jenseisert.bsky.social · 03/04/2026
Warm thanks to Julio C. Magdalena de la Fuente, Noa Feldman, and Andreas Bauer.
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Jens Eisert @jenseisert.bsky.social · 03/04/2026
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...
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Jens Eisert @jenseisert.bsky.social · 02/04/2026
In the absence of quantum error correction, circuits of #quantumcomputers can be logarithmically deep. www.nature.com/articles/s41...
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Jens Eisert @jenseisert.bsky.social · 02/04/2026
Unfortunately not, no.
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Jens Eisert @jenseisert.bsky.social · 28/03/2026
But this is a good point: We will add a comment to this effect.
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Jens Eisert @jenseisert.bsky.social · 28/03/2026
Good question: I would say, quite natural.
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Reposted by Jens Eisert
Joschka 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.com
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...
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Jens Eisert @jenseisert.bsky.social · 28/03/2026
Thanks for posting.
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Reposted by Jens Eisert
Elies Gil-Fuster @eliesgf.bsky.social · 25/03/2026
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
arxiv.org
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...
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Jens Eisert @jenseisert.bsky.social · 28/03/2026
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...
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Jens Eisert @jenseisert.bsky.social · 28/03/2026
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.
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Jens Eisert @jenseisert.bsky.social · 08/03/2026
Wonderful talk, wonderful seeing you.
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Jens Eisert @jenseisert.bsky.social · 08/03/2026
Thanks for posting.
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Jens Eisert @jenseisert.bsky.social · 06/03/2026
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.
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