A new study addresses a foundational problem in the theory of driven quantum matter by extending the Středa formula to non-equilibrium regimes. It demonstrates that a superficially trivial “sum of zeros” encodes a universal, quantized magnetic response—one that is intrinsically topological and uniquely emergent under non-equilibrium driving conditions.

Imagine a strange material being rhythmically pushed—tapped again and again by invisible hands. These are periodically driven quantum systems, or Floquet systems, where energy is no longer conserved in the usual sense. Instead, physicists speak of quasienergy—a looping spectrum with no clear start or end.

When scientists measure how such a system responds to a magnetic field, every single contribution seems to vanish—like adding an infinite list of zeros. And yet, the total stubbornly comes out finite, quantized, and very real.