Invariance of Energy Exchange Rates for Light-Dressed Systems

Light-driven matter can exhibit electronic and optical properties qualitatively distinct from those observed at equilibrium. We demonstrate that while strong driving can tune the absorption properties, the energy exchange rate of any light-dressed system remains invariant compared to its bare counterpart. This invariance is evidenced experimentally by the vanishing integrated area of the transient absorption spectrum. We present a general theory alongside experimental results obtained from halide perovskite nanocrystals under strong off-resonance driving. This unexpected result provides useful insights into the optical properties of matter that is driven far from equilibrium.