71 citations · 167 across the 6 of their papers we have counts for
6 papers
Massless multifold Hopf semimetals
Ansgar Graf, Frédéric Piéchon
Three-dimensional topological semimetals exhibit linear energy band crossing points that act as monopoles of Berry curvature. Here, an alternative class of semimetals is introduced…
Designing flat-band tight-binding models with tunable multifold band touching points
Ansgar Graf, Frédéric Piéchon
Being dispersionless, flat bands on periodic lattices are solely characterized by their macroscopically degenerate eigenstates: compact localized states (CLSs) in real space and Bl…
An ultralow-noise superconducting radio-frequency ion trap for frequency metrology with highly charged ions
J. Stark, C. Warnecke, S. Bogen +17
We present a novel ultrastable superconducting radio-frequency (RF) ion trap realized as a combination of an RF cavity and a linear Paul trap. Its RF quadrupole mode at 34.52 MHz r…
Berry Curvature and Quantum Metric in -band systems -- an Eigenprojector Approach
Ansgar Graf, Frédéric Piéchon
The eigenvalues of a parameter-dependent Hamiltonian matrix form a band structure in parameter space. In such -band systems, the quantum geometric tensor (QGT), consisting of th…
Theory of magnetotransport in shaped topological insulator nanowires
Ansgar Graf, Raphael Kozlovsky, Klaus Richter +1
We show that shaped topological insulator (TI) nanowires, i.e. such that their cross-section radius varies along the wire length, can be tuned into a number of different transport…
Magnetoconductance, Quantum Hall Effect, and Coulomb Blockade in Topological Insulator Nanocones
Raphael Kozlovsky, Ansgar Graf, Denis Kochan +2
Magnetotransport through cylindrical topological insulator (TI) nanowires is governed by the interplay between quantum confinement and geometric (Aharonov-Bohm and Berry) phases. H…