Andreas Bluhm

The QIP 2026 call for papers is out! QIP 2026 will be held in Riga, Latvia from January 24–30, 2026. See you there!
qip2026.lu.lv

I am currently looking for a PhD student who would like to work on position-based cryptography. Details can be found here: andreasbluhm.eu/wp-content/u...

Please spread the word!

Thanks to Tim Möbus, Tuvia Gefen, Yu Tong, Albert H. Werner and Cambyse Rouzé for the great collaboration!

Our main technical tool is a new adiabatic approximation for general Lindbladian evolutions with unbounded generators which should also be helpful elsewhere. For example, we can quantify with it how photon-driven dissipation leads to an effective evolution on the code space for bosonic cat codes.

Heisenberg-limited Hamiltonian learning for interacting bosons We develop a protocol for learning a class of interacting bosonic Hamiltonians from dynamics with Heisenberg-limited scaling. For Hamiltonians with an underlying bounded-degree graph structure, we can...

Before, we could either do Heisenberg-limited learning for Bose-Hubbard type models scirate.com/arxiv/2307.0..., or learn arbitrary Hamiltonians with engineered dissipation, but not with Heisenberg scaling scirate.com/arxiv/2307.1.... Our new paper shows that you can have the best of both worlds.

Heisenberg-limited Hamiltonian learning continuous variable systems via engineered dissipation Discrete and continuous variables oftentimes require different treatments in many learning tasks. Identifying the Hamiltonian governing the evolution of a quantum system is a fundamental task in quant...

New day, new paper, this time on Heisenberg-limited Hamiltonian learning for continuous variable systems with engineered dissipation: scirate.com/arxiv/2506.0.... The idea is to use strong dissipation to restrict the Hamiltonian evolution onto a convenient subspace where we can learn it.

Thanks to my PhD student Simon Höfer, Alex May, Mikka Stasiuk, Philip Verduyn Lunel and @henryyuen.bsky.social for the great collaboration! And congratulations to Simon for his first paper.

In the longer term, our aim is to be able to put NLQC tasks into classes of equally hard problems, like complexity classes. This would allow us to identify the hard NLQC problems that we would like to use for quantum position verification, because they are hard for attackers to solve.

In particular, we have shown that two protocols for quantum position verification, the f-route and the f-measure protocol, are equally secure, i.e., if you can attack one, you can attack the other. This gives the first subexponential upper bound on the entanglement needed to attack f-measure.

A complexity theory for non-local quantum computation Non-local quantum computation (NLQC) replaces a local interaction between two systems with a single round of communication and shared entanglement. Despite many partial results, it is known that a cha...

We have a new preprint out on the topic of quantum position verification and non-local quantum computation (NLQC): scirate.com/arxiv/2505.2.... We are comparing different NLQC tasks and find reductions between them (in the sense of if I can do task 1, then I can do task 2 with an extra EPR pair).

Liste des postes de chaires de professeur junior de CNRS Sciences informatiques 2025 Le CNRS recrute des chercheurs et chercheuses sur des Chaires de professeur junior (CPJ) dans plusieurs domaines relatifs aux sciences informatiques.

CNRS is opening a call for CPJ (chair de professeur junior), a kind of tenure track with very good conditions. One position is open for quantum computing, and one of the hosting labs is LIG in beautiful Grenoble! The application deadline is July 14th.

www.ins2i.cnrs.fr/fr/cnrsinfo/...

Thanks to my coauthors for the great collaboration!

To unite these different phenomena, we consider multimeters, i.e., collections of measurements. Many of them, e.g., compatible measurements, classical simulations of measurements, or the compression of measurements can be viewed as factorizations of these multimeters through different state spaces.

Factorization of multimeters: a unified view on nonclassical quantum phenomena Quantum theory exhibits various nonclassical features, such as measurement incompatibility, contextuality, steering, and Bell nonlocality, which distinguish it from classical physics. These phenomena ...

If you are interested in quantum non-classicality, you might enjoy our new preprint: scirate.com/arxiv/2504.1.... In it, we use the framework of general probabilistic theories to connect different forms of non-classicality, in particular measurement incompatibility, steering, and Bell non-locality.

FZ Jülich is hiring a PhD candidate which will be co-supervised by myself at U Cologne. Interested in benchmarking/characterisation, in working in a highly collaborative environment, and want to see your work being used in experiments? Consider applying!
www.fz-juelich.de/en/careers/j...

Master in Mathematical Physics

If you're an undergraduate student interested in the mathematics of quantum physics and general relativity, consider the

Tübingen International M.Sc. Program in #MathematicalPhysics

www.math.uni-tuebingen.de/en/mmp

Opens for applications today

Summer school Mathematics and Physics of Quantum Computing and Quantum Learning, on the island of Porquerolles, France

www.quantiki.org/conference/m...

PhD Opportunities – Quantum Algorithms for Quantum Chemistry. Join the Quantum for Life Center at the University of Copenhagen as PhD student! Work on quantum algorithms for chemistry with Prof. Matthias Christandl & co-supervision by Prof. Markus Reiher (ETH Zurich). 1/n

⏰ Beyond IID 2025 Conference just announced

sites.google.com/view/beyondi...

We're looking for a new addition to our group. Drop me a message if you're interested!

Belavkin-Staszewski Quantum Markov Chains It is well-known that the conditional mutual information of a quantum state is zero if, and only if, the quantum state is a quantum Markov chain. Replacing the Umegaki relative entropy in the definiti...

Oh, thanks for pointing that out! Turns out I missed some numbers when copying it, here is the correct link scirate.com/arxiv/2501.0...

Thanks to my coauthors for the great collaboration! 7/7

Finally, we show that certain states associated to thermal equilibrium states of quantum spin chains with local, finite-range, translation-invariant interactions at any positive temperature exhibit a superexponentially decreasing conditional mutual information. 6/7

This allows us to find a recovery map (which is CP but not trace preserving) for the BS-CMI, similarly to the Petz recovery map arising from ordinary CMI. Moreover, we investigate what it means to be an approximate BS-quantum Markov chain. 5/7

The BS-quantum Markov chains in our title are the states with zero BS-CMI. In our preprint, we fully characterize this class of states and we show that their form is intimately related to the ordinary quantum Markov chains that we all know and cherish. 4/7

Conditional Independence of 1D Gibbs States with Applications to Efficient Learning We show that spin chains in thermal equilibrium have a correlation structure in which individual regions are strongly correlated at most with their near vicinity. We quantify this with alternative not...

Choosing the Belavkin-Staszewski relative entropy instead of the Umegaki, we obtain the BS-CMI, which has for example already been studied in scirate.com/arxiv/2402.1... and been shown to exhibit superexponential decay in thermal equilibrium in 1D. 3/7

You probably know that a quantum state has conditional mutual information (CMI) equal to zero iff it is a quantum Markov chain, which are known to have a specific form. But what happens if we replace the (Umegaki) relative entropy in the definition of the CMI by another one? 2/7

Happy to announce a new preprint together with Ángela Capel, Pablo Costa Rico and Anna Jenčová, in which we study a class of states we call Belavkin-Staszewski Quantum Markov Chains scirate.com/arxiv/2501.097 1/7