Concept

Ising critical exponents

Related publications (27)

Conformal Data for the O(3) Wilson-Fisher Conformal Field Theory from Fuzzy Sphere Realization of the Quantum Rotor Model

We present a model for strongly interacting fermions with internal O(3) symmetry on the fuzzy sphere that (i) preserves the rotational symmetry of the fuzzy sphere and (ii) undergoes a quantum phase transition in the (2+1)-dimensional O(3) Wilson-Fisher universality class. Using exact diagonalization and density matrix renormalization group, we locate the quantum critical point via conformal perturbation theory and obtain scaling dimensions from finite-size spectra. We identify 24 primary operators and dete

2026

Kinetic Equilibrium Prediction at TCV using RAPTOR and FBT

Olivier Sauter

We present results from a new Kinetic-Equilibrium Prediction (KEP) workflow and shot preparation for full TCV discharges, by coupling predict-first RAPTOR transport simulations with FBT inverse equilibrium calculations. RAPTOR is a 1.5D transport code which has been extensively used for plasma shot optimization and real-time modeling. We show that rapid pre-shot simulations can be performed directly using information from the pulse schedule across a wide range of plasma shapes and scenar

IOP Publishing2026

Exact diagonalization, matrix product states and conformal perturbation theory study of a 3D Ising fuzzy sphere model

Numerical studies of phase transitions in statistical and quantum lattice models provide crucial insights into the corresponding Conformal Field Theories (CFTs). In higher dimensions, comparing finite-volume numerical results to infinite-volume CFT data is facilitated by choosing the sphere S^{d-1} as the spatial manifold. Recently, the fuzzy sphere regulator [Zhu et al, Phys. Rev. X 13, 021009 (2023)] has enabled such studies with exact rotational invariance, yielding impressive agreement with known 3D Isi

Stichting SciPost2025

Coupling transport simulations with Phase-Space-Reconstruction methods and Lyapunov exponents analyses

Nuclear fusion in tokamaks represents a promising solution for producing clean and sustainable energy. However, achieving stable and reliable operation requires controlling plasma dynamics over long periods. A crucial part of this challenge lies in the ability to predict plasma behavior from limited measurements, in order to anticipate and mitigate potential instabilities. In this context, it is particularly useful to develop tools that can evaluate the predictability horizon of a dynamic system, that is, t

EPFL2025

High power modular LED-based illumination system for lithography applications

Hans Peter Herzig, Toralf Scharf, Wilfried Noell, Raoul Kirner, Johana Bernasconi

Mask-aligner lithography is a technology used to transfer patterns with critical dimensions in the micrometer range from below 1 micron for contact printing to a dozen of microns in proximity printing. This technology is widely used in the fabrication of M ...

2018

Exciton-polariton flows in cross-dimensional junctions

Hugo Pierre Alexandre Flayac

We study the nonequilibrium exciton-polariton condensation in 1D to 0D and 1D to quasi-2D junctions by means of non-resonant spectroscopy. The shape of our potential landscape allows to probe the resonant transmission of a propagating condensate between a ...

Amer Physical Soc2017

Multimaterial Nanoporous Membranes Shaped through High Aspect-Ratio Sacrificial Silicon Nanostructures

Philippe Renaud, Arnaud Bertsch, Niccolo Piacentini, Stefano Silvio Giovanni Varricchio

We present an innovative fabrication method for solid-state nanoporous membranes based on the casting of sacrificial silicon nanostructures. The process allows the individual definition of geometry and placement of each nanopore through e-beam lithography ...

Amer Chemical Soc2017

Ising Model: Local Spin Correlations and Conformal Invariance

We study the 2-dimensional Ising model at critical temperature on a smooth simply-connected graph Ω.We rigorously prove the conformal invariance of arbitrary spin-pattern probabilities centered at a point a and derive formulas to compute the probabilities as functions of the conformal map from Ω to the unit disk. Our methods extend those of [Hon10] and [CHI13] which proved conformal invariance of energy densities and spin correlations for points fixed far apart from each other. We use discrete complex analy

2015

Nonlinear Midinfrared Photothermal Spectroscopy Using Zharov Splitting and Quantum Cascade Lasers

Hatice Altug

We report on the Mid-infrared nonlinear photothermal spectrum of the neat liquid crystal 4-octyl-4'-cyanobiphenyl (8CB) using a tunable Quantum Cascade Laser (QCL). The nonequilibrium steady state characterized by the nonlinear photothermal infrared respon ...

2014

Geomorphic Signatures on Brutsaert Base Flow Recession Analysis: case study of 27 Swiss catchments

Recession flow analysis are crucial in many areas of water resource management and useful to forecast base flow in gauged rivers. Moving from a classical recession curve analysis method, a large set of recession curves has been analyzed from Swiss streamflow data of 27 watersheds. For these catchments, digital elevation models have been precisely analyzed and a method aimed at the geomorphic origins of recession curves has been applied to the Swiss dataset. The method links river network morphology, epitomi

2013

Simulated annealing study of the disordered quantum magnet LiHoxEryY1-x-yF4

Thermal and quantum phase transitions of some rare earth compounds (LiErF4, LiYbF4, LiGdF4 and LiTmF4) are established using the mean field theory. These preliminary calculations allowed evidencing the existence of a novel high-field antiferromagnetic phase in LiErF4, and a still unexplained symmetry breaking in LiGdF4. But the discrepancies with experimental results impel a more sophisticated method. We then present analytical and numerical evidence for the validity of an effective approach to the descript

2012

On the locality of MHD turbulence scale fluxes

The scale locality of energy fluxes for magnetohydrodynamics (MHD) is investigated numerically for stationary states of turbulence. Two types of forces are used to drive turbulence, a kinetic force that acts only on the velocity field and a kinetic-inducti ...

American Institute of Physics (AIP)2011

On the spectral estimates for Schrödinger type operators. The case of small local dimension

The behavior of the discrete spectrum of the Schr"odinger operator

-\D - V

, in quite a general setting, up to a large extent is determined by the behavior of the corresponding heat kernel

P(t;x,y)

t\to 0

and

t\to\infty

. If this behavior is powerlike, i.e.,

\|P(t;\cdot,\cdot)\|_{L^\infty}=O(t^{-\delta/2}),\ t\to 0;\qquad \|P(t;\cdot,\cdot)\|_{L^\infty}=O(t^{-D/2}),\ t\to\infty,

then it is natural to call the exponents

\delta,D

"{\it the local dimension}" and "{\it the dimension at infinity}

2010

Mean-Field calculations on the diluted dipolar magnet LiHo1−xYxF4

We define a new inhomogeneous mean-field algorithm to study the magnetic alloy LiHo1−xYxF4. The phase diagrams in the Hx-T, x-T and x-Hx planes are computed. The calculated critical temperature is overestimated by 27% and the critical field is underestimated by 29%. The later discrepancy is due to the hyperfine coupling which has been neglected in our model. The reasons for the temperature discrepancy are discussed. The critical exponents for the magnetic susceptibility are found to be mean-field ( = ′ = 1)

2009

Thermal destruction of chiral order in a two-dimensional model of coupled trihedra

We introduce a minimal model describing the physics of classical two-dimensional (2D) frustrated Heisenberg systems, where spins order in a nonplanar way at T=0. This model, consisting of coupled trihedra (or Ising-RP3 model), encompasses Ising (chiral) degrees of freedom, spin-wave excitations, and Z2 vortices. Extensive Monte Carlo simulations show that the T=0 chiral order disappears at finite temperature in a continuous phase transition in the 2D Ising universality class, despite misleading intermediate

2008

Highly frustrated magnetic clusters: The kagome on a sphere

Frédéric Mila

We present a detailed study of the low-energy excitations of two existing finite-size realizations of the planar kagome Heisenberg antiferromagnet on the sphere: the cuboctahedron and the icosidodecahedron. After highlighting a number of special spectral f ...

2008

Analysis of a Robust Reputation System for Self-Organized Networks

Jean-Yves Le Boudec

Self-organized networks require some mechanism to ensure cooperation and fairness in the face of individual utility maximizing users and potential malicious attacks. Otherwise, network performance can be seriously deteriorated. One promising approach are decentralized reputation systems. However, these are vulnerable to users with an interest in passing on false information. Robustness against liars has not yet been analyzed in detail. In this paper, we provide a first step to the robustness analysis of a r

2004

Piezoresistivity and conductance anisotropy of tunneling-percolating systems

Thomas Maeder, Peter Ryser, Claudio Grimaldi

We propose a theory of the origin of transport nonuniversality in disordered insulating-conducting compounds based on the interplay between microstructure and tunneling processes between metallic grains dispersed in the insulating host. We show that if the metallic phase is arranged in quasi- one-dimensional chains of conducting grains, then the distribution function of the chain conductivities g has a power-law divergence for g-->0, leading to nonuniversal values of the transport critical exponent t. We ev

2003

Segregated tunneling-percolation model for transport nonuniversality

Thomas Maeder, Peter Ryser, Claudio Grimaldi

2003

Bounded Luttinger liquids as a universality class of quantum critical behavior

Marco Grioni

We show that one-dimensional quantum systems with gapless degrees of freedom and open boundary conditions form a universality class of quantum critical behavior, which we propose to call ''bounded Luttinger liquids." They share the following properties with ordinary (periodic) Luttinger liquids: the absence of fermionic quasiparticle excitations, charge-spin separation, and anomalous power-law correlations with exponents whose scaling relations are parametrized by a single coupling constant per degree of fr

2000

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