Universal Sign Control of Coupling in Tight-Binding Lattices.
We present a method of locally inverting the sign of the coupling term in tight-binding systems, by means of inserting a judiciously designed ancillary site and eigenmode matching of the resulting vertex triplet. Our technique can be universally applied to all lattice configurations, as long as the individual sites can be detuned. We experimentally verify this method in laser-written photonic lattices and confirm both the magnitude and the sign of the coupling by interferometric measurements. Based on these findings, we demonstrate how such universal sign-flipped coupling links can be embedded into extended lattice structures to impose a Z_{2}-gauge transformation. This opens a new avenue for investigations on topological effects arising from magnetic fields with aperiodic flux patterns or in disordered systems.
Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
Robert
R
Keil
Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom.
Charles
C
Poli
Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany.
Matthias
M
Heinrich
Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom.
Jake
J
Arkinstall
Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
Gregor
G
Weihs
Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom.
Henning
H
Schomerus
Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany.
Alexander
A
Szameit