activity
20152026
most citedGoing Beyond Gadgets: The Importance of Scalability for Analogue Quantum Simulators

4 citations · 10 across the 19 of their papers we have counts for

collaborators

20 papers

math.CO2026

From Kreweras walks to branching perimeter processes of percolated triangulations

Renan Gross, Emmanuel Kammerer, Frederik Ravn Klausen

In this note, using a result of Bernardi, Holden and Sun, we give an explicit geometric relation between the perimeter of the peeling process along the percolation interface of a t…

math.PR2026

The End of the Double Random Current

Ulrik Thinggaard Hansen, Frederik Ravn Klausen

The Ising correlation function can be expressed in terms of connectivity probabilities of a random graph known as the double random current. In 2016, Duminil-Copin asked whether th…

math.PR2026

The Supercritical Loop O(1) and Random Current models: Uniqueness and Mixing

Ulrik Thinggaard Hansen, Frederik Ravn Klausen

Much recent rigorous study of the classical ferromagnetic Ising model has been powered by its graphical representations, such as the random current and loop O(1) model (high temper…

math.PR2026

Half-plane non-coexistence without FKG

Frederik Ravn Klausen, Noah Kravitz

For an edge percolation measure on the infinite square lattice, let (respectively, ) denote its marginal (respectively, the marginal of its planar d…

math.NT2026

Powers in prime bases and a problem on central binomial coefficients

Sebastian Tim Holdum, Frederik Ravn Klausen, Peter Michael Reichstein Rasmussen

It is an open problem whether is divisible by 4 or 9 for all . In connection with this, we prove that for a fixed uneven the asymptotic density of '…

math.PR2025

A simple proof of exponential decay for the near-critical planar Ising model

Jianping Jiang, Frederik Ravn Klausen

For the Ising model defined on at critical temperature with external field , we give a simple and elementary proof that its truncated two-point function…

math.PR2025

A General Coupling for Ising Models and Beyond

Ulrik Thinggaard Hansen, Jianping Jiang, Frederik Ravn Klausen

The couplings between the Ising model and its graphical representations, the random-cluster, random current and loop models, are put on common footing through a gen…

quant-ph2025★ 2 cited

Fault-tolerant quantum simulation of generalized Hubbard models

Andreas Juul Bay-Smidt, Frederik Ravn Klausen, Christoph Sünderhauf +3

Quantum simulations of strongly interacting fermionic systems, such as those described by the Hubbard model, are promising candidates for useful early fault-tolerant quantum comput…

math.PR2024

Non-uniqueness of phase transitions for graphical representations of the Ising model on tree-like graphs

Ulrik Thinggaard Hansen, Frederik Ravn Klausen, Peter Wildemann

We consider the graphical representations of the Ising model on tree-like graphs. We construct a class of graphs on which the loop model and the single random curre…

math-ph2023

Random Problems in Mathematical Physics

Frederik Ravn Klausen

This PhD thesis deals with a number of different problems in mathematical physics with the common thread that they have probabilistic aspects. The problems all stem from mathematic…

math-ph2023

Decoherence is an echo of Anderson localization in open quantum systems

Frederik Ravn Klausen, Simone Warzel

We study the time evolution of single-particle quantum states described by a Lindblad master equation with local terms. By means of a geometric resolvent equation derived for Lindb…

quant-ph2023★ 4 cited

Going Beyond Gadgets: The Importance of Scalability for Analogue Quantum Simulators

Dylan Harley, Ishaun Datta, Frederik Ravn Klausen +4

Quantum hardware has the potential to efficiently solve computationally difficult problems in physics and chemistry to reap enormous practical rewards. Analogue quantum simulation…

math.PR2023

The Uniform Even Subgraph and Its Connection to Phase Transitions of Graphical Representations of the Ising Model

Ulrik Thinggaard Hansen, Boris Kjær, Frederik Ravn Klausen

The uniform even subgraph is intimately related to the Ising model, the random-cluster model, the random current model, and the loop (1) model. In this paper, we first…

physics.soc-ph2023

Stochastic cellular automaton model of culture formation

Frederik Ravn Klausen, Asbjørn Bækgaard Lauritsen

We introduce a stochastic cellular automaton as a model for culture and border formation. The model can be conceptualized as a game where the expansion rate of cultures is quantifi…

math-ph2022★ 2 cited

Spectra of generators of Markovian evolution in the thermodynamic limit: From non-Hermitian to full evolution via tridiagonal Laurent matrices

Frederik Ravn Klausen

It is shown that generators of single-particle, translation-invariant Lindblad operators on the infinite line are unitarily equivalent to direct integrals of finite-range bi-infini…

math-ph2022

Strict monotonicity, continuity and bounds on the Kertész line for the random-cluster model on

Ulrik Thinggaard Hansen, Frederik Ravn Klausen

Ising and Potts models can be studied using the Fortuin-Kasteleyn representation through the Edwards-Sokal coupling. This adapts to the setting where the models are exposed to an e…

math-ph2021

Mass scaling of the near-critical 2D Ising model using random currents

Frederik Ravn Klausen, Aran Raoufi

We examine the Ising model at its critical temperature with an external magnetic field on for . A new proof of exponential decay of the…

math-ph2020

On monotonicity and couplings of random currents and the loop--model

Frederik Ravn Klausen

Using recent couplings we provide counterexamples to monotonicity properties of percolation models related to graphical representations of the Ising model. We further prove a new c…

math.OA2017★ 2 cited

Combinatorial classification of quantum lens spaces

Peter Lunding Jensen, Frederik Ravn Klausen, Peter M. R. Rasmussen

We answer the question of how large the dimension of a quantum lens space must be, compared to the primary parameter , for the isomorphism class to depend on the secondary param…

math.NT2015

On a Conjecture on the Representation of Positive Integers as the Sum of Three Terms of the Sequence

Sebastian Tim Holdum, Frederik Ravn Klausen, Peter Michael Reichstein Rasmussen

We prove some cases of a conjecture by Farhi on the representation of every positive integer as the sum of three terms of the sequence . Th…