Frederik Ravn Klausen | University of Cambridge

Postdoctoral Researcher
University of Cambridge

Email: frk23@cam.ac.uk

October 2025: If you want to read about the probability of overrepresentation for Danish elections look here. Feel free to contact me on email or cell: 40372316.

Hi! I'm a postdoc at Cambridge working in probability theory and mathematical physics.

Before that I was at Princeton, in QMATH and NQCP at the University of Copenhagen.

Below you will find an overview of my research interest as well as a list of publications.

Research Interests

I'm broadly interested in mathematical physics, probability and quantum information and recently also elections. Often, I use classical and quantum stochastic geometric methods to investigate various problems concerning the Ising model, Anderson localization, open quantum systems etc.

You are very welcome to reach out! I have a long list of things that I'd like to know - some of them are on Mathoverflow.

Publications

A list of my publications can also be found on Google Scholar.

A. J. Bay-Smidt, F. R. Klausen, C. Sünderhauf, R. Izsák, G. C. Solomon, N. S. Blunt.
Fault-Tolerant Quantum Simulation of Generalized Hubbard Models , PRX Quantum, 6, 030348, 2025.

U. Thinggaard Hansen, F. R. Klausen, P. Wildemann.
Non-uniqueness of phase transitions for graphical representations of the Ising model on tree-like graphs , ALEA, Latin American Journal of Probability and Mathematical Statistics, 22, 889-904, 2025.

U. Hansen, B. Kjær, F. R. Klausen.
The Uniform Even Subgraph and Its Connection to Phase Transitions of Graphical Representations of the Ising Model , Communications in Mathematical Physics , 2025.

F. R. Klausen, S. Warzel.
Decoherence is an echo of Anderson localization in open quantum systems , Annales Henri Poincaré, 2025.

D. Harley, I. Datta, F. R. Klausen, A. Bluhm, D. S. França, A. Werner, M. Christandl.
Going Beyond Gadgets: The Importance of Scalability for Analogue Quantum Simulators , Nature Communications, 2024.

F. R. Klausen, A. Lauritzen.
A stochastic cellular automaton model of culture formation , Phys. Rev. E, 108, 054307, 2023.

U. Hansen, F. R. Klausen.
Strict monotonicity, continuity and bounds on the Kertész line for the random-cluster model on ℤ^d , Journal of Mathematical Physics, 2023.

F. R. Klausen, A. Raoufi.
Mass scaling of the near-critical 2D Ising model using random currents , Journal of Statistical Physics, 2022.

F. R. Klausen.
On monotonicity and couplings of random currents and the loop-O(1)-model , ALEA. Latin American Journal of Probability and Mathematical Statistics, 2022.

A. Bluhm, M. Christandl, F. Gesmundo, F. R. Klausen, L. Mančinska, V. Steﬀan, D. S. França, A. Werner.
SARS-CoV-2 transmission routes from genetic data: A Danish case study , PloS One, 2020.

P. Jensen, F. R. Klausen, P. Rasmussen.
Combinatorial classification of quantum lens spaces , Pacific Journal of Mathematics, 2018.

S. Holdum, F. R. Klausen, P. Rasmussen.
Powers in Prime Bases and a Problem on the Central Binomial Coefficient , Integers: Electronic Journal of Combinatorial Number Theory , 2014.

S. Holdum, F. R. Klausen, P. Rasmussen.
On a Conjecture on the Representation of Positive Integers as the Sum of Three Terms of the Sequence ⌊n² / a⌋ , The Journal of Integer Sequences, 2014.

Preprints

U. T. Hansen, J. Jiang, F. R. Klausen
General coupling for Ising models and beyond , 2025.

F. R. Klausen, A. Werner.
Spectra of Lindbladians on the infinite line: From non-Hermitian to full evolution via tridiagonal Laurent matrices , 2022.
J. Elklit, S. Holudm, F. R. Klausen.
What is wrong with the proportionality in the Parliamentary Elections Act—and what can be done about it? , (accepted in) Politica, 2025.

Preprints (only here)

F. R. Klausen.
The Disproportionate Power of Votes Near Electoral Thresholds, 2025. Download (PDF)

S. Holdum, F. R. Klausen.
Impossibility Theorem for Two-Tier Electoral Systems, 2025. Download (PDF)
F. R. Klausen.
Sandsynligheden for overrepræsentation ved Folketingsvalg, 2025. Download (PDF)