What is it about?
Just as irrational numbers can be continuously approximated by a series of continued fractions, quasiperiodic systems can be approximated by a series of periodic lattices. By this means, the topological properties of quasiperiodic systems can be defined. You might think that, in this way, the topological properties of quasiperiodic structures should be the limit of their counterpart periodic systems. In principle, this is true, but it turns out that it is much easier: we find that the topological properties of quasiperiodic systems are the same as those of their corresponding first-level periodic systems. The reason is the "topological memory effect," which transfers topological properties from one level to the next.
Featured Image
Why is it important?
This research work reveals the fundamental connection in topological properties between quasiperiodic systems and their corresponding periodic systems, discovering the topological "memory effect" in quasiperiodic structures. The study extends the concept of topological transport from traditional periodic systems to quasiperiodic systems, broadening the design freedom for topological materials and opening up new avenues for obtaining topological structures.
Perspectives
The results, namely, the topological pumping and topological memory effect can be straightforwardly extended to other physical systems, including atomic systems, acoustics, condensate of quasiparticles, and condensed matter systems. Our findings can also be extended to two- and three-dimensional incommensurate systems, such as dynamic moiré lattices in various physical systems. This opens fascinating possibilities of engineering novel topological routing of wavepackets within higher-dimensional spaces lacking periodicity. Thus, we anticipate that our findings will be interesting for a broad scientific community, and may stimulate experiments on topological effects in qua-si-periodic systems in other areas of physics.
Fangwei Ye
Shanghai Jiao Tong University
Read the Original
This page is a summary of: Observation of Thouless pumping of light in quasiperiodic photonic crystals, Proceedings of the National Academy of Sciences, November 2024, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2411793121.
You can read the full text:
Contributors
The following have contributed to this page
