Indeed, because he's still missing the Dulwich Peace Prize.
17.01.2026 18:45
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Indeed, because he's still missing the Dulwich Peace Prize.
If you are interested in doing a postdoc with me, please apply to the IQC postdoctoral fellowship here: iqc-uwaterloo.slideroom.com#/login/progr...
(I/III) We're excited to announce a new tenure track opening! The position is called 'quantum informatics' and is affiliated with our QUICK group within the CS+AI division at @jku.at 🇦🇹. Application deadline is November 30th, 2025: www.jku.at/en/the-jku/w...
This week, we're in beautiful Kraków for a conference on tensor networks and all their applications. My PhD students Dimitris and Lev already gave amazing talks about discrete-holographic boundary symmetries and von Neumann algebras in holographic codes!
Or dare we say... Engineering? 😬
You can tell that the #QIP2026 deadline has not yet passed, since @zoltanzimboras.bsky.social has not given word on his submission yet.
Postdoc job! I expect to have an opening at Johns Hopkins for a postdoctoral researcher working somewhere in the broad realms of physics, philosophy, and complexity. Apply at Academic Jobs Online:
academicjobsonline.org/ajo/jobs/30496
Thanks Zoltan! You should petition the museum to add some hyperbolic tilings as well, there's plenty of material in our papers. 😁
It would be a lost opportunity if they didn't call it the Ministry of Magic (state distillation).
Looking for a postdoc to work on bosonic quantum error correction!
Join me and the QAT team at ENS & INRIA Paris — flexible start date.
Details here 👉 recrutement.inria.fr/public/class... or feel free to reach out!
For more details, you'll have to read our paper! As always, many thanks for the support of Berlin Quantum for our work at @freieuniversitaet.bsky.social.
arxiv.org/abs/2103.02634
This suggests a deep relationship between equilibration strength and entanglement phases in many-body quantum systems! The main idea: More entanglement = stronger equilibration.
For the condensed-matter theorists among you, our work also leads to an interesting conjecture: RTNs on different geometries describe different phases of entanglement scaling. We show that D_eff follows a sharp hierarchy between area- and volume-law phases.
This means that random tensor networks know a lot more about holographic dynamics than we expected, and may be able to hold more insights into (holographic) quantum gravity.
And surprisingly, the result matches gravitational degree-of-freedom counting in holography: If we "fuse" tensors together, i.e., replace part of the bulk geometry by a "black hole", D_eff always *increases*. Just as in gravity, where a black hole is the highest-entropy state!
This brings us to holography: For holographic RTNs, we can now compute the minimum effective dimension D_eff that describes late-time dynamics! From the geometry and bond dimension of the RTN alone, we can determine how complex its dynamics must be.
Now here's the kicker: For random ensembles, we can strictly lower-bound D_eff *without knowing H*! In a sense, the randomness cancels out its exact eigenstate structure. This is a trick we learned from Haferkamp et al., who used it on random MPS:
arxiv.org/abs/2103.02634
The key quantity to describe the strength of equilibration is the "effective dimension" D_eff, which basically counts how many (energy) states are needed to describe late-time dynamics.
Here's how it works: In a quantum system, expectation values of observables fluctuate. At late times, even a pure state will *equilibrate*, meaning that local expectation values will fluctuate within a fixed window. This happens for all Hamiltonians H with "non-degenerate gaps".
In our paper, we bring in ideas from quantum statistical mechanics to show that the opposite is true: Thanks to the randomness in RTNs, we can probe late-time dynamics without knowing the explicit Hamiltonian! The key concept that enables this is called *equilibration*.
That makes choosing a Hamiltonian that performs time evolution on the boundary difficult: Any choice, e.g. motivated from AdS/CFT arguments, would time-evolve different RTN samples differently. Thus, it seemed that randomness made time evolution impossible to describe!
This sparked hundreds of follow-up papers - many of which refined the original proposal - but there was one limitation: Random tensor networks (RTNs) produce an *ensemble* of states, with every random sample looking quite different locally.
Some background: In a seminal paper from 2016, Hayden et al. showed that tensor networks with locally random tensors, if put on a hyperbolic geometry, reproduce quantum states that very closely resemble boundary states of the AdS/CFT duality.
arxiv.org/abs/1601.01694
Very happy to have this paper with @jenseisert.bsky.social and his PhD student Shozab Qasim out on the @arxiv.bsky.social!
It achieves something that, until recently, I thought to be impossible: To use random tensor networks to study holographic *dynamics*.
They've obviously been best friends for years, I don't know why this is so hard for the media to acknowledge.
At least Chamberlain got a piece of paper
Back from an exciting week visiting the great @zoltanzimboras.bsky.social in Budapest!
As you can see, I was also very busy pensively staring at Platonic solids at the Hungarian National Museum.
A big thanks to my amazing collaborators from TU Delft, U Queensland, and Okinawa's OIST!
And of course, we're always grateful for the local support from FU Berlin @freieuniversitaet.bsky.social and Berlin Quantum.
Our conclusion: Holographic codes aren't just cool physical models, but might actually be useful!
We've already shown they have more nice features in two further papers:
1) Reaching the Hashing bound: arxiv.org/abs/2408.06232
2) Building fault-tolerant logic: arxiv.org/abs/2504.10386
Does that mean that holographic codes are the future of quantum computing? We don't know yet, because real quantum errors are very complicated, and every quantum hardware is different. But at least in simple models, our codes behave as well as state-of-the-art ones!