Joschka Roffe

Joschka Roffe

@qec.codes

Quantum Error Correction | Quantum Software Lab | University of Edinburgh Homepage: https://roffe.eu

550 followers 585 following53 posts

📢 New paper. 𝗡𝗲𝗮𝗿𝗲𝘀𝘁-𝗻𝗲𝗶𝗴𝗵𝗯𝗼𝘂𝗿 𝗴𝗮𝘁𝗲𝘀 𝗮𝗿𝗲 𝗮𝗹𝗹 𝘆𝗼𝘂 𝗻𝗲𝗲𝗱: 𝗛𝗶𝗴𝗵-𝗿𝗮𝘁𝗲 𝗾𝘂𝗮𝗻𝘁𝘂𝗺 𝗹𝗼𝘄-𝗱𝗲𝗻𝘀𝗶𝘁𝘆 𝗽𝗮𝗿𝗶𝘁𝘆-𝗰𝗵𝗲𝗰𝗸 𝗰𝗼𝗱𝗲𝘀 𝗼𝗻 𝗮 𝗽𝗹𝗮𝗻𝗮𝗿 𝗴𝗿𝗶𝗱. scirate.com/arxiv/2606.1... 𝘁𝗹𝗱𝗿; For several years now, we have been advocating for qLDPC codes as a resource-efficient alternative to the surface code. 1/3

scirate.comNearest-neighbour gates are all you need: High-rate quantum low-density parity-check codes on a planar gridHigh-performance quantum low-density parity-check codes promise substantial reductions in the overhead of fault-tolerant quantum computation, but most constructions require long-range connectivity or ...

But this has always come with the caveat that they require long-range interactions, making them far harder to engineer into practical quantum computing systems. In this work we show we can have the best of both worlds: efficient qLDPC codes that can be implemented on a planar 2D grid of qubits. 2/3

This is not a marginal improvement: instances of the code family we introduce can reduce qubits by up to an order of magnitude relative to the rotated surface code, and our circuit-level numerical simulations demonstrate improvements in logical error rate suppression by a factor of up to 1000x. 3/3

Back in Santa Barbara this week for #QEC2026. Looking forward to meeting colleagues, old and new, and hearing about the latest and greatest in QEC!

🚨Registration deadline today! TartanQEC Workshop 24-26 June. Poster submissions remain open until end-of-day (AOE). Sign up now 👇 qec.codes/tartan2026

TartanQEC Workshop | University of Edinburgh 24-26 June. The full programme is now available. Poster submissions are still being accepted & registration deadline is 1st June. Sign up now 👇 qec.codes/tartan2026/t...

qec.codesTartanQEC TimetableTartanQEC Workshop timetable, 24-26 June 2026, School of Informatics, University of Edinburgh.

🚨TartanQEC Workshop. Final day to submit a talk abstract 👇 qec.codes/tartan2026/

qec.codesTartanQEC WorkshopTartanQEC Workshop, 24-26 June 2026, School of Informatics, University of Edinburgh.

📢 TartanQEC Workshop. The deadline for abstract submission is tomorrow. Submit your best work now 👇 qec.codes/tartan2026

qec.codesTartanQEC WorkshopTartanQEC Workshop, 24-26 June 2026, School of Informatics, University of Edinburgh.

📢 TartanQEC Workshop, 24-26 June, University of Edinburgh. Along with @jdpritchard.bsky.social, I am organising an event on practical methods for quantum error correction. See details and submit your best work for poster/talk before 8th May 👇 qec.codes/tartan2026/

qec.codesTartanQEC WorkshopTartanQEC Workshop, 24-26 June 2026, School of Informatics, University of Edinburgh.

Joschka Roffe reposted

Jonathan Pritchard

@jdpritchard.bsky.social

Interested in qauntum error correction? Join @qec.codes and I at the TartanQEC conference in Edinburgh 24-26 June 26 as part of the Quantum Fringe. Abstract submission open until 8th May - for details and registration see qec.codes/tartan2026/

qec.codesTartanQEC WorkshopTartanQEC Workshop, 24-26 June 2026, School of Informatics, University of Edinburgh.

📢 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...

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In this work we address this limitation through a code–logic co-design approach. First, we introduce a new family of codes that admits an addressable logical-qubit basis. Second, we develop a code surgery protocol that allows operations on this basis to be executed in parallel. 3/n

We show explicit examples where up to k/2 Pauli-product measurements can be performed simultaneously, saturating the same upper bound achieved by the surface code. The result is a single computational block that naturally supports parallel logical operations, i.e. a QGPU.

📢 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...

quantum computation. A key challenge, however, is that compiling logic is much more difficult than in surface codes: logical operators can overlap, meaning there limited scope for executing operations in parallel. 2/n

Great day back in Durham visiting @durhamqlm.bsky.social to give a seminar on QEC and our recent work at Quantum Software Lab. Also fun to discuss the fault-tolerance of the Welsh towname Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch w/ @ifanghughes.bsky.social @tobifranzen.bsky.social

Joschka Roffe reposted

@timohillmann.bsky.social

Working on LSD was fun! - Our paper on Localized statistics decoding (LSD) for qLDPC codes is now in print. LSD is a highly parallelizable, reliability-guided inversion decoder that exploits the clustering of errors. Think of it as a parallel version of OSD. www.nature.com/articles/s41...

nature.comLocalized statistics decoding for quantum low-density parity-check codes - Nature CommunicationsQuantum low-density parity-check (QLDPC) codes offer lower overhead than topological quantum error-correcting codes, but decoding remains a key challenge for scalable fault-tolerant quantum computing....

📢 Our paper, 𝗟𝗼𝗰𝗮𝗹𝗶𝘀𝗲𝗱 𝘀𝘁𝗮𝘁𝗶𝘀𝘁𝗶𝗰𝘀 𝗱𝗲𝗰𝗼𝗱𝗶𝗻𝗴 𝗳𝗼𝗿 𝗾𝘂𝗮𝗻𝘁𝘂𝗺 𝗹𝗼𝘄-𝗱𝗲𝗻𝘀𝗶𝘁𝘆 𝗽𝗮𝗿𝗶𝘁𝘆-𝗰𝗵𝗲𝗰𝗸 𝗰𝗼𝗱𝗲𝘀, is now published in Nature Communications (Nature Portfolio). Great to see it in print! www.nature.com/articles/s41...

nature.comLocalized statistics decoding for quantum low-density parity-check codes - Nature CommunicationsQuantum low-density parity-check (QLDPC) codes offer lower overhead than topological quantum error-correcting codes, but decoding remains a key challenge for scalable fault-tolerant quantum computing....

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parity-check codes. Our LSD algorithm works as a post-processor for standard belief propagation algorithms and, crucially, is designed from the bottom-up with parallism in mind. This makes it a suitable for implementation on specialised hardware (e.g., GPUs, FPGAs, ASICS) for real-time decoding.

A very enjoyable collaboration @timohillmann.bsky.social, @lucasberent.bsky.social, Armanda Quintavalle, Robert Wille, and @jenseisert.bsky.social

📢 Our paper, 𝗟𝗼𝗰𝗮𝗹𝗶𝘀𝗲𝗱 𝘀𝘁𝗮𝘁𝗶𝘀𝘁𝗶𝗰𝘀 𝗱𝗲𝗰𝗼𝗱𝗶𝗻𝗴 𝗳𝗼𝗿 𝗾𝘂𝗮𝗻𝘁𝘂𝗺 𝗹𝗼𝘄-𝗱𝗲𝗻𝘀𝗶𝘁𝘆 𝗽𝗮𝗿𝗶𝘁𝘆-𝗰𝗵𝗲𝗰𝗸 𝗰𝗼𝗱𝗲𝘀, is now published in Nature Communications (Nature Portfolio). Great to see it in print! www.nature.com/articles/s41...

nature.comLocalized statistics decoding for quantum low-density parity-check codes - Nature CommunicationsQuantum low-density parity-check (QLDPC) codes offer lower overhead than topological quantum error-correcting codes, but decoding remains a key challenge for scalable fault-tolerant quantum computing....

𝘁𝗹;𝗱𝗿; Any quantum error correction (QEC) protocol is only ever as good as its decoder: a classical co-processor tasked with intrepting stabiliser measurements in real-time. In this work, we propose localised statistics decoding (LSD) as a very general decoding algorithm for quantum low-density ...

Your wish will be fufilled: this will be in arXiv V2 👀

Alexis Morvan@amorvan.bsky.social

Color code decoding with some big claim: arxiv.org/abs/2508.15743 I wish they could try to benchmark this decoder against the experimental color code data from arxiv.org/pdf/2412.14256 zenodo.org/records/1423... We are releasing experimental data so people can try out their decoding algorithms!

arxiv.orgColour Codes Reach Surface Code Performance using Vibe DecodingTwo-dimensional quantum colour codes hold significant promise for quantum error correction, offering advantages such as planar connectivity and low overhead logical gates. Despite their theoretical ap...

Joschka Roffe reposted

@amorvan.bsky.social

Color code decoding with some big claim: arxiv.org/abs/2508.15743 I wish they could try to benchmark this decoder against the experimental color code data from arxiv.org/pdf/2412.14256 zenodo.org/records/1423... We are releasing experimental data so people can try out their decoding algorithms!

arxiv.orgColour Codes Reach Surface Code Performance using Vibe DecodingTwo-dimensional quantum colour codes hold significant promise for quantum error correction, offering advantages such as planar connectivity and low overhead logical gates. Despite their theoretical ap...

Joschka Roffe reposted

@preskill.bsky.social

The QEC25 conference hosted by @yaleqi.bsky.social was really excellent, and videos of all talks are available. So much recent progress on quantum error correction! qec25.yalepages.org

qec25.yalepages.orgQEC25

James Mills introducing Logical Accreditation to #QEC2025 at @yaleqi.bsky.social See our recent preprint here: arxiv.org/abs/2508.05523

Joschka Roffe reposted

Josu Etxezarreta Martinez

@katutxakur.bsky.social

Check out the V2 of our qLDPC decoding paper "An almost-linear time decoding algorithm for quantum LDPC codes under circuit-level noise". The meme summarizes our approach. @qec.codes

Joschka Roffe reposted

@jenseisert.bsky.social

Hardware-tailored logical Clifford circuits for stabilizer codes scirate.com/arxiv/2505.2... This first first author paper of Eric appeared yesterday, but was not picked up by Scirate. It suggests novel strategies for implementing logical Cliffords of stabilizer codes under hardware constraints.

Joschka Roffe reposted

@jenseisert.bsky.social

Hardware-tailored logical Clifford circuits for stabilizer codes arxiv.org/abs/2505.20261 It is important to identify strategies for implementing Clifford unitaries at the logical level of stabilizer codes in #quantumerrorcorrection, respecting hardware constraints. Here is one such strategy.

📣 New pre-print on the arXiv today on generalisation of surface code lattice surgery to arbitrary CSS codes w/ Clément Poirson and Robert Booth. Congrats to @clemenson7.bsky.social on his first paper! 🎉

clemenson7.bsky.social@clemenson7.bsky.social

So here it is, my first first-author paper is live on the arXiv arxiv.org/abs/2505.01370

arxiv.orgEngineering CSS surgery: a fault-tolerant CNOT for any CSS codesWe introduce a framework for implementing logic in CSS-style quantum error correction codes, building on the surgery methods of Cowtan and Burton [CB24]. Our approach offers a systematic methodology f...

Happy World Quantum Day! I'm excited to announce that I will be starting a new group dedicated to quantum error correction (QEC) at The University of Edinburgh Quantum Software Lab, funded by an EPSRC Quantum Technology Career Acceleration Fellowship!

My group will tackle both the theoretical and practical challenges of building fault-tolerant quantum computers. I'll be advertising postdoctoral research positions soon. Please get in touch if you're interested in joining or collaborating.

The group's research include: - Investigating new QEC protocols. - Designing QEC decoding algorithms for specialised hardware. - Logical gates for fault-tolerant logic. - Design and implementation of QEC experiments, - Developing open-source QEC software. More details soon!

📣 New paper: Computing Efficiently in QLDPC Codes w/ @TeamPhotonic! Lots of great stuff here: - New subsystem codes w/ transversal gates that efficiently compile full Clifford Group. - Single-shot decoding - Huge circuit-level logic sims scirate.com/arxiv/2502.0...

scirate.comComputing Efficiently in QLDPC CodesIt is the prevailing belief that quantum error correcting techniques will be required to build a utility-scale quantum computer able to perform computations that are out of reach of classical computer...

🚨Reminder: The deadline to apply for the Quantum Informatics CDT is tomorrow (15th Jan). Apply below 👇 www.quantuminformatics-cdt.ac.uk

quantuminformatics-cdt.ac.ukQI CDT – EPSRC Centre for Doctoral Training in Quantum Informatics

Joschka Roffe reposted

@sflammia.bsky.social

Submissions for QEC 2025 are now open through March 28. This will easily be the most exciting conference on quantum error correction yet! Conference homepage: qec25.yalepages.org EasyChair submission page: easychair.org/my/conferenc...

qec25.yalepages.orgQEC25

Joschka Roffe reposted

qctip2025.bsky.social

@qctip2025.bsky.social

Submissions for QCTiP 2025 are now open.

🎓 PhD in Quantum Error Correction Applications are open for a 4-year collaborative PhD between @edinburghuni.bsky.social and the NQCC. Project: designing QEC protocols and decoders for the NQCC's neutral atom quantum computing systems. Apply by Jan 31 👇 informatics.ed.ac.uk/study-with-u...

informatics.ed.ac.ukPhD studentship in Quantum Error CorrectionDeadline: 31 January 2025 (or until the position is filled)

I've enjoyed teaching students at Edinburgh University about QEC this term. Here I am introducing the famous [[9,1,3]] Shor code.

PSA: The Tanner graph representation is the best way of depicting surface codes.

Remember: the surface code threshold is not the breakeven point (for finite-size codes).

📢PhD Positions in Quantum Computing Applications are now open for the new CDT in Quantum Informatics. We are recruiting 16 students to start Sept 2025. Positions are fully funded for 4 years. Apply now: quantuminformatics-cdt.ac.uk

quantuminformatics-cdt.ac.ukQI CDT – EPSRC Centre for Doctoral Training in Quantum Informatics

The CDT is spread across five universities: Edinburgh, Heriot Watt, Strathclyde, UCL and Oxford. The first training year will be spent at Edinburgh, and then you will have the option to pursue PhD projects at any of the five universities.

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