Zobrazeno 1 - 10
of 288
pro vyhledávání: '"P. Roentgen"'
Exceptional points are special degeneracy points in parameter space that can arise in (effective) non-Hermitian Hamiltonians describing open quantum and wave systems. At an n-th order exceptional point, n eigenvalues and the corresponding eigenvector
Externí odkaz:
http://arxiv.org/abs/2409.13434
We demonstrate that rotation symmetry is not a necessary requirement for the existence of fractional corner charges in Cn-symmetric higher-order topological crystalline insulators. Instead, it is sufficient to have a latent rotation symmetry, which m
Externí odkaz:
http://arxiv.org/abs/2405.02704
Autor:
Eek, Lumen, Moustaj, Anouar, Röntgen, Malte, Pagneux, Vincent, Achilleos, Vassos, Smith, Cristiane Morais
Publikováno v:
Phys. Rev. B 109, 045122 (2024)
The Hatano-Nelson and the non-Hermitian Su-Schrieffer-Heeger model are paradigmatic examples of non-Hermitian systems that host non-trivial boundary phenomena. In this work, we use recently developed graph-theoretical tools to design systems whose is
Externí odkaz:
http://arxiv.org/abs/2310.11988
Autor:
Röntgen, Malte, Chen, Xuelong, Gao, Wenlong, Pyzh, Maxim, Schmelcher, Peter, Pagneux, Vincent, Achilleos, Vassos, Coutant, Antonin
The Su-Schrieffer-Heeger (SSH) chain is the reference model of a one-dimensional topological insulator. Its topological nature can be explained by the quantization of the Zak phase, due to reflection symmetry of the unit cell, or of the winding numbe
Externí odkaz:
http://arxiv.org/abs/2310.07619
Publikováno v:
Quantum 8, 1469 (2024)
Here, we investigate the fractal-lattice Hubbard model using various numerical methods: exact diagonalization, the self-consistent diagonalization of a (mean-field) Hartree-Fock Hamiltonian and state-of-the-art Auxiliary-Field Quantum Monte Carlo. We
Externí odkaz:
http://arxiv.org/abs/2310.07813
Autor:
Röntgen, Malte, Richoux, Olivier, Theocharis, Georgios, Morfonios, Christian V., Schmelcher, Peter, del Hougne, Philipp, Achilleos, Vassos
We explore the scattering of waves in designed asymmetric one-dimensional waveguide networks. We show that the reflection between two ports of an asymmetric network can be identical over a broad frequency range, as if the network was mirror-symmetric
Externí odkaz:
http://arxiv.org/abs/2305.02786
Symmetries and tunability are of fundamental importance in wave scattering control, but symmetries are often obvious upon visual inspection which constitutes a significant vulnerability of metamaterial wave devices to reverse-engineering risks. Here,
Externí odkaz:
http://arxiv.org/abs/2305.00906
Autor:
Moustaj, Anouar, Röntgen, Malte, Morfonios, Christian V., Schmelcher, Peter, Smith, Cristiane Morais
Publikováno v:
New J. Phys. 25 093019 (2023)
The Fibonacci chain, i.e., a tight-binding model where couplings and/or on-site potentials can take only two different values distributed according to the Fibonacci word, is a classical example of a one-dimensional quasicrystal. With its many intrigu
Externí odkaz:
http://arxiv.org/abs/2208.05178
Mirror symmetry of a wave system imposes corresponding even or odd parity on its eigenmodes. For a discrete system, eigenmode parity on a specific subset of sites may also originate from so-called latent symmetry. This symmetry is hidden, but can be
Externí odkaz:
http://arxiv.org/abs/2204.07232
The analysis of diagonalizable matrices in terms of their so-called isospectral reduction represents a versatile approach to the underlying eigenvalue problem. Starting from a symmetry of the isospectral reduction, we show in the present work that it
Externí odkaz:
http://arxiv.org/abs/2105.12579