46 citations · 155 across the 20 of their papers we have counts for
20 papers
Bohr--Sommerfeld rules for systems
Simon Becker, Setsuro Fujiié, Jens Wittsten
We present a complete, self-contained formulation of the Bohr--Sommerfeld quantization rule for a semiclassical self-adjoint system on the real line, arising from a si…
Warehouse storage and retrieval optimization via clustering, dynamical systems modeling, and GPU-accelerated routing
Magnus Bengtsson, Jens Wittsten, Jonas Waidringer
This paper introduces a warehouse optimization procedure aimed at enhancing the efficiency of product storage and retrieval. By representing product locations and order flows withi…
Discrete vs. continuous in the semiclassical limit
Simon Becker, Jens Wittsten, Maciej Zworski
We compare the bottom of the spectrum of discrete and continuous Schrödinger operators with periodic potentials with barriers at the boundaries of their fundamental domains. Our re…
Chiral limit of twisted trilayer graphene
Simon Becker, Tristan Humbert, Jens Wittsten +1
We initiate the mathematical study of the Bistritzer-MacDonald Hamiltonian for twisted trilayer graphene in the chiral limit (and beyond). We develop a spectral theoretic approach…
Hofstadter butterflies and metal/insulator transitions for moiré heterostructures
Simon Becker, Lingrui Ge, Jens Wittsten
We consider a tight-binding model recently introduced by Timmel and Mele for strained moiré heterostructures. We consider two honeycomb lattices to which layer antisymmetric shear…
Semiclassical quantization conditions in strained moiré lattices
Simon Becker, Jens Wittsten
In this article we generalize the Bohr-Sommerfeld rule for scalar symbols at a potential well to matrix-valued symbols having eigenvalues that may coalesce precisely at the bottom…
Uniqueness theorems for weighted harmonic functions in the upper half-plane
Anders Olofsson, Jens Wittsten
We consider a class of weighted harmonic functions in the open upper half-plane known as -harmonic functions. Of particular interest is the uniqueness problem for such functions…
Finite-difference modeling of 2-D wave propagation in the vicinity of dipping interfaces: a comparison of anti-aliasing and equivalent medium approaches
Erik F. M. Koene, Jens Wittsten, Johan O. A. Robertsson
Finite-difference (FD) modeling of seismic waves in the vicinity of dipping interfaces gives rise to artifacts. Examples are phase and amplitude errors, as well as staircase diffra…
Quenched limit theorems for random U(1) extensions of expanding maps
Yong Moo Chung, Yushi Nakano, Jens Wittsten
The Lyapunov spectra of random U(1) extensions of expanding maps on the torus were investigated in our previous work [NW2015]. Using the result, we extend the recent spectral appro…
Spectral characterization of magic angles in twisted bilayer graphene
Simon Becker, Mark Embree, Jens Wittsten +1
Twisted bilayer graphene (TBG) has been experimentally observed to exhibit almost flat bands when the twisting occurs at certain magic angles. In this letter, we report new results…
Mathematics of magic angles in a model of twisted bilayer graphene
Simon Becker, Mark Embree, Jens Wittsten +1
We provide a mathematical account of the recent Physical Reviews Letter by Tarnopolsky--Kruchkov--Vishwanath. The new contributions are a spectral characterization of magic angles,…
Complex eigenvalue splitting for the Dirac operator
Koki Hirota, Jens Wittsten
We analyze the eigenvalue problem for the semiclassical Dirac (or Zakharov-Shabat) operator on the real line with general analytic potential. We provide Bohr-Sommerfeld quantizatio…
Removing numerical dispersion from linear evolution equations
Jens Wittsten, Erik F. M. Koene, Fredrik Andersson +1
We describe a method for removing the numerical errors in the modeling of linear evolution equations that are caused by approximating the time derivative by a finite difference ope…
Perfect partial reconstructions for multiple simultaneous sources
Jens Wittsten, Fredrik Andersson, Johan Robertsson +1
A major focus of research in the seismic industry of the past two decades has been the acquisition and subsequent separation of seismic data using multiple sources fired simultaneo…
Quantization conditions of eigenvalues for semiclassical Zakharov-Shabat systems on the circle
Setsuro Fujiié, Jens Wittsten
Bohr-Sommerfeld type quantization conditions of semiclassical eigenvalues for the non-selfadjoint Zakharov-Shabat operator on the circle are derived using an exact WKB method. The…
The partial captivity condition for U(1) extensions of expanding maps on the circle
Yushi Nakano, Masato Tsujii, Jens Wittsten
This paper concerns the compact group extension \[ f:\mathbb{T}^2\to \mathbb{T}^2,\quad f (x,s)= (E(x), s+τ(x)\ \text{mod }1) \] of an expanding map $E:\mathbb{S}^1\to \mathbb{S}^1…
Generalized axially symmetric potentials with distributional boundary values
Jens Wittsten
We study a counterpart of the classical Poisson integral for a family of weighted Laplace differential equations in Euclidean half space, solutions of which are known as generalize…
On the spectra of quenched random perturbations of partially expanding maps on the torus
Yushi Nakano, Jens Wittsten
We consider quenched random perturbations of skew products of rotations on the unit circle over uniformly expanding maps on the unit circle. It is known that if the skew product sa…
On the microlocal properties of the range of systems of principal type
Nils Dencker, Jens Wittsten
The purpose of this paper is to study microlocal conditions for inclusion relations between the ranges of square systems of pseudodifferential operators which fail to be locally so…
On Some Microlocal Properties of the Range of a Pseudo-Differential Operator of Principal Type
Jens Wittsten
The purpose of this paper is to obtain microlocal analogues of results by L. H örmander about inclusion relations between the ranges of first order differential operators with coef…