Scientist, professor of quantum physics at @FU_Berlin and affiliated with @HZBde and @FraunhoferHHI. @ERC_Research fellow. Founder of @Qonsultancy.
Berlin, Deutschland
Joined October 2014
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Come work with us! We offer another round of attractive #postdocposition|s and #PhDposition|s in #quantuminformationtheory, on topics ranging from abstract #mathematical themes to pragmatically motivated questions, in an open and stimulating discussion climate. Topics include
- #quantuminformationtheory,
- #quantumerrorcorrection,
- #tensornetworks,
- #quantumalgorithms.
physik.fu-berlin.de/en/einri…
I had no idea when we started working on this that the vision of Microcrypt - built on the idea to construct computationally secure quantum cryptography, including bit commitments, from quantum pseudorandomness that could persist even if P=NP rules out classical one-way functions - would suddenly become so interesting.
nitter.cf/jenseisert/status/2099…
Warm congratulations, dear Paul Faehrmann, on your wonderful viva. You blew everybody away with your insights into near-term and early fault-tolerant quantum computing. What a celebration!
When I search for "Dear Prof. Jense" in my inbox, I get several screens filled with messages, mostly applications for PhD and postdoctoral positions. I am still thinking about what conclusions to meaningfully draw from this about standards of professional care in academic communication.
Jens Eisert retweeted
A trillion is one of the biggest numbers I personally know. So I was very surprised when someone posted on our slack to say we'd actually sampled a trillion shots of parts of our architecture. How!? New decoder! 1/4
iceberg-quantum.com/blog/rel…
Can a quantum learner with limited memory benefit from a much more powerful helper—even if that helper cannot be trusted?
quantum-journal.org/papers/q…
In our new work, we investigate learning and testing under resource constraints, such as limited memory or restricted access to data. We ask whether delegation can help: can an untrusted party with far greater resources enable a learner to solve problems more efficiently?
The answer depends crucially on how they communicate.
For a broad range of scenarios, we prove that classical interaction provides no advantage. In particular, for the vast majority of learning and testing problems in which quantum memory is a meaningful resource, a memory-constrained quantum learner cannot overcome its limitations by exchanging classical messages with a quantum prover that has unrestricted memory.
Quantum communication opens up new possibilities. For specific learning and testing problems, we construct interactive proof protocols that allow verifiers with limited quantum memory to gain significant advantages by delegating to untrusted provers. The verifier can check the outcome within its own resource constraints. This identifies a fundamental role for quantum communication: it can enable a small quantum device to make verifiable use of resources beyond its own capabilities.
I am very happy to see this work, the result of a wonderful collaboration with Matthias Caro, Marcel Hinsche, Marios Ioannou, Alexander Nietner and @rndm_wlks now published in @quantumjournal.
#QuantumComputing #QuantumInformation #MachineLearning
Jens Eisert retweeted
Immensément triste de vous annoncer le décès de mon oncle
Claude Cohen-Tannoudji, prix Nobel de physique en 1997, est décédé à l’âge de 93 ans
lefigaro.fr/sciences/claude-…
To sharpen students’ awareness of the mathematical fine print in quantum theory, I took these two assumptions, both commonly found in quantum mechanics textbooks, and used them to show in just two lines that 1 = 0. It is fun to see how genuinely puzzled students are by this—and how few people spot the problem. It makes for an illuminating teaching moment.
Today, we gathered in Munich for the symposium of the Heisenberg Society. Two speakers explored the history of quantum mechanics and Heisenberg’s role in shaping it.
The highlight was the presentation of the prestigious Heisenberg Medal to Reinhard Werner, one of the formative figures of quantum information theory and mathematical physics. I had the great honor of delivering the laudatio. Reinhard then reflected on Heisenberg’s legacy and the foundations of quantum mechanics, before we concluded with a fascinating lecture on attempts to bring quantum physics and gravity closer together.
Warmest congratulations, Reinhard, on this richly deserved distinction
Jens Eisert retweeted
What does it take for relativistic quantum field theory to emerge from a lattice system? Our new work connects this question to a resource from quantum information theory: nonstabilizerness, also referred as as “magic”.
scirate.com/arxiv/2610.20790
The bridge is the structure of local observable algebras. Type III von Neumann factors are characteristic of relativistic quantum field theory. We prove that lattice stabilizer systems—states without magic—exclude type III factors from the central decomposition of their local algebras. For the hyperfinite factors of Araki, Woods and Powers, we establish a quantitative equivalence: the limiting factor is of type III precisely when the locally optimized min-relative entropy of magic diverges.
In this setting, the required resource is therefore an infinite amount of magic. This gives a rigorous connection between a quantum information resource and the algebraic structure of quantum field theory, supporting the proposal that infinite magic is a necessary ingredient for a relativistic continuum to emerge.
Warm thanks to Leo Shaposhnik, @lorenzo_leone_, @bittel_l, Dimitris Saraidaris, and @PhysicistAlex for the wonderful collaboration.
What does it take for relativistic quantum field theory to emerge from a lattice system? Our new work connects this question to a resource from quantum information theory: nonstabilizerness, also referred as as “magic”.
scirate.com/arxiv/2610.20790
The bridge is the structure of local observable algebras. Type III von Neumann factors are characteristic of relativistic quantum field theory. We prove that lattice stabilizer systems—states without magic—exclude type III factors from the central decomposition of their local algebras. For the hyperfinite factors of Araki, Woods and Powers, we establish a quantitative equivalence: the limiting factor is of type III precisely when the locally optimized min-relative entropy of magic diverges.
In this setting, the required resource is therefore an infinite amount of magic. This gives a rigorous connection between a quantum information resource and the algebraic structure of quantum field theory, supporting the proposal that infinite magic is a necessary ingredient for a relativistic continuum to emerge.
Warm thanks to Leo Shaposhnik, @lorenzo_leone_, @bittel_l, Dimitris Saraidaris, and @PhysicistAlex for the wonderful collaboration.
On Friday, October 16, I will have the honour of delivering the laudatio for my friend and colleague Reinhard Werner on the occasion of his receiving the Heisenberg Medal. I am very much looking forward to celebrating him and his remarkable contributions to quantum theory.
heisenberg-gesellschaft.de/u…
One of my favourite courses to teach is elementary quantum mechanics. It offers students their first encounter with a physical theory of nature—arguably the best we have—that makes extraordinarily precise predictions, yet defies our everyday intuition. It has been a joy to teach this course in a packed lecture theatre. And it was for this important course that I had to leave the @FU_Berlin retreat.
physik.fu-berlin.de/en/einri…
Brandenburg, surrounding Berlin, is such a beautiful place. It is a tradition around my birthday to skate a 40 km circuit of the #FlaemingSkate with the family.
Jens Eisert retweeted
The future will be quantum — but how exactly?
Semiconductors and quantum technologies are converging, as discussed at #FIRST by FMD. Where will quantum computing create value, and what capabilities should Europe build now?
qonsultancy.tech/
