Keil, Robert and Poli, Charles Joseph and Heinrich, Matthias and Arkinstall, Jake and Weihs, Gregor and Schomerus, Henning and Szameit, Alexander (2016) Universal sign control of coupling in tight-binding lattices. Physical review letters, 116 (21): 213901. ISSN 1079-7114
1512.01158v2.pdf - Accepted Version
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Abstract
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 Z2-gauge transformation. This opens a new avenue for investigations on topological effects arising from magnetic fields with aperiodic flux patterns or in disordered systems.