Spin-orbit coupling in a hexagonal ring of pendula

Year: 2017

Authors: Salerno G., Berardo A., Ozawa T., Price HM., Taxis L., Pugno NM., Carusotto I.

Autors Affiliation: Univ Trento, INO, CNR, BEC Ctr, Via Sommarive 14, I-38123 Povo, Italy; Univ Trento, Dept Phys, Via Sommarive 14, I-38123 Povo, Italy; Univ Trento, Lab Bioinspired & Graphene Nanomech, Dept Civil Environm & Mech Engn, Via Mesiano 77, I-38123 Trento, Italy; Fdn Bruno Kessler, Ctr Mat & Microsyst, Via Sommarive 18, I-38123 Povo, Italy; Queen Mary Univ London, Sch Engn & Mat Sci, Mile End Rd, London E1 4NS, England.

Abstract: We consider the mechanical motion of a system of six macroscopic pendula which are connected with springs and arranged in a hexagonal geometry. When the springs are pre-tensioned, the coupling between neighbouring pendula along the longitudinal (L) and the transverse (T) directions are different: identifying the motion along the L and T directions as the two components of a spin-like degree of freedom, we theoretically and experimentally verify that the pre-tensioned springs result in a tunable spin-orbit coupling. We elucidate the structure of such a spin-orbit coupling in the extended two-dimensional honeycomb lattice, making connections to physics of graphene. The experimental frequencies and the oscillation patterns of the eigenmodes for the hexagonal ring of pendula are extracted from a spectral analysis of the motion of the pendula in response to an external excitation and are found to be in good agreement with our theoretical predictions. Weanticipate that extending this classical analogue of quantum mechanical spin-orbit coupling to two-dimensional lattices will lead to exciting new topological phenomena in classical mechanics.

Journal/Review: NEW JOURNAL OF PHYSICS

Volume: 19      Pages from: 55001-1  to: 55001-15

More Information: We thank Gabriele Ferrari, Alberto Amo, and Jacqueline Bloch for fruitful discussions on different aspects of this work. We acknowledge Giuseppe Vettori for his work during an early stage of the experiment. This work was supported by the ERC through the QGBEgrant, by the EU-FET Proactive grant AQuS, Project No. 640800, and by the Autonomous Province of Trento, partially through the project SiQuro. HMPwas also supported by the EC through the H2020 Marie Sklodowska-Curie Action, Individual Fellowship Grant No: 656093 ’SynOptic’. NMP is supported by the European Research Council (ERC StG Ideas 2011 BIHSNAM n. 279985, ERC PoC 2015 SILKENE nr. 693670), by the European Commission under the Graphene Flagship (WP14 Polymer Composites, no. 696656).
KeyWords: topological mechanics; spin-orbit coupling; mechanical graphene; classical pendula
DOI: 10.1088/1367-2630/aa6c03

Citations: 17
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