# gst: odd electrical circuits

<< Non-reciprocal interactions in elastic media give rise to rich non-equilibrium behaviors, but controllable experimental realizations of such odd elastic phenomena remain scarce. Building on recent breakthroughs in electrical analogs of non-Hermitian solid-state systems, (AA) design and analyze scalable odd electrical circuits (OECs) as exact analogs of an odd solid. >>

AA << show that electrical work can be extracted from OECs via cyclic excitations and trace the apparent energy gain back to active circuit elements. (They) show that OECs host oscillatory modes that resemble recent experimental observations in living chiral crystals and identify active resonances that reveal a perspective on odd elasticity as a mechanism for mechanical amplification. >>️

Harry Walden, Alexander Stegmaier, et al. Odd electrical circuits. arXiv: 2503.14383v1 [cond-mat.soft]. Mar 18, 2025.

https://arxiv.org/abs/2503.14383

Also: chiral, elastic, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, chirality, chiral crystals, chiral oscillations, chiral waves, oddity, odd elastic materials

# gst: apropos of 'strange states', the modulation of PdGa crystals from conventional to 'exotic' behaviors

<< In topological materials, electrons can display behavior that is fundamentally different from that in 'conventional' matter, and the magnitude of many such 'exotic' phenomena is directly proportional to an entity known as the Chern number. New experiments establish for the first time that the theoretically predicted maximum Chern number can be reached—and controlled—in a real material. >>

<<  in the topological semimetal palladium gallium (PdGa) one of the most common classifiers of topological phenomena, the Chern number, can reach the maximum value that is allowed in any metallic crystal. That this is possible in a real material has never been shown before. (..)  the team has established ways to control the sign of the Chern number, which might bring new opportunities for exploring, and exploiting, topological phenomena. >>

Cherned up to the maximum. Paul Scherrer Institute. Jul 9, 2020.

https://phys.org/news/2020-07-cherned-maximum.html   

<< Here, (AA) show that the chiral crystal palladium gallium (PdGa) displays multifold band crossings, which are connected by exactly four surface Fermi arcs, thus proving that they carry the maximal Chern number magnitude of 4. By comparing two enantiomers, (They) observe a reversal of their Fermi-arc velocities, which demonstrates that the handedness of chiral crystals can be used to control the sign of their Chern numbers. >>

Niels B. M. Schroter, Samuel Stolz, et al. Observation and control of maximal Chern numbers in a chiral topological semimetal.  Science. Vol. 369, Issue 6500, pp. 179-183. doi: 10.1126/ science.aaz3480. Jul 10, 2020.

https://science.sciencemag.org/content/369/6500/179    

Also

D.J. Thouless, F. D.M. Haldane, J. M.Kosterlitz  << opened the door on an unknown world where matter can assume strange states. >> Oct 4, 2016

https://www.nobelprize.org/prizes/physics/2016/press-release/