Phys.org  August 27, 2024 Due to their bosonic nature, excitons are expected to condense and exhibit superfluidity at sufficiently low temperatures. In interacting Chern insulators, excitons may inherit the nontrivial topology and quantum geometry from the underlying electron wavefunctions. A team of researchers in the US (University of Oklahoma, City University of New York, Harvard University) theoretically investigated the excitonic bound states and superfluidity in flat-band insulators pumped with light. They found that the exciton wavefunctions exhibited vortex structures in momentum space, with the total vorticity being equal to the difference of Chern numbers between the conduction and valence bands. […]