Modern tests of Lorentz invariance

Motivated by ideas about quantum gravity, a tremendous amount of effort over the past decade has gone into testing Lorentz invariance in various regimes. This review summarizes both the theoretical frameworks for tests of Lorentz invariance and experimental advances that have made new high precision tests possible. The current constraints on Lorentz violating effects from both terrestrial experiments and astrophysical observations are presented.Comment: Modified and expanded discussions of various points. Numerous references added. Version matches that accepted by Living Reviews in Relativit

Switching chiral solitons for algebraic operation of topological quaternary digits

Chiral objects can be found throughout nature1–4; in condensed matter chiral objects are often excited states protected by a system’s topology. The use of chiral topological excitations to carry information has been demonstrated, where the information is robust against external perturbations5,6. For instance, reading, writing, and transfer of binary information have been demonstrated with chiral topological excitations in magnetic systems, skyrmions7–14, for spintronic devices13–19. The next step is logic or algebraic operations of such topological bits20–22. Here, we show experimentally the switching between chiral topological excitations or chiral solitons of dierent chirality in a one-dimensional electronic system with Z4 topological symmetry23,24. We found that a fast-moving achiral soliton merges with chiral solitons to switch their handedness.This can lead to the realization of algebraic operation of Z4 topological charges25. Chiral solitons could be a platform for storage and operation of robust topological multi-digit information. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.4