Invariants should be well-formed formulas, that is, they should be logical statements (with a truth-value--true, of course), in the predicate calculus or rigorous English. A good invariant is a ...

Topological insulators are fascinating states of matter exhibiting protected edge states and robust quantized features in their bulk. Here we propose and validate experimentally a method to detect ...

Topological quantum phases cannot be characterized by Ginzburg–Landau type order parameters, and are instead described by non-local topological invariants. Experimental platforms capable of realizing ...