Journal Club

Excerpt from today's episode:⁠ - - - - -⁠ In 2016, the Nobel Prize in Physics was awarded to three men (Thouless, Haldane and Kosterlitz) for work they had done largely 30-50 years before. That work had been on topological phase transitions and the topological states of matter. These were not specific discoveries per se, but foundational work on the deeper theoretical framework that eventually made the entire field of "topological materials" possible. ⁠ ⁠ Before that work, we mostly classified phases of matter using what we call "symmetry breaking". Here, the word "symmetry" does not just mean mirror symmetry. It refers more generally, to situations where a system still looks the same after some transformation or change in perspective. ⁠ A liquid, for example, is highly symmetric in the sense that it usually looks and behaves roughly the same no matter which direction you examine it from. Its molecules can move around freely and there are no fixed positions or preferred directions.⁠ But freeze that liquid into a solid, and the atoms lock themselves into a rigid structure. Now certain directions and arrangements become special. Rotate the system or shift your perspective and it no longer looks equivalent in every direction the way the liquid did.⁠ - - - - -⁠ Watch the full episode at JournalClub.io⁠