Fragile topology and flat-band superconductivity in the strong-coupling regime

Recent theoretical works unveiled that crystalline symmetries can stabilize topologically fragile Bloch bands that challenge our very notion of topology: one can trivialize these bands through the addition of trivial Bloch bands. Here, we show via auxiliary-field Monte Carlo simulations how fragile topology enhances the superfluid weight and hence the superconducting critical temperature. This feature is particularly relevant in flat-band systems where the conventional contribution to the superfluid weight vanishes and might explain the high transition temperature observed in magic-angle twisted bilayer graphene.