  It is shown that strong driving of a quantum system substantially enhances
the Lamb shift induced by broadband reservoirs which are typical for
solid-state devices. By varying drive parameters the impact of environmental
vacuum fluctuations with continuous spectral distribution onto system
observables can be tuned in a distinctive way. This provides experimentally
feasible measurement schemes for the Lamb shift in superconducting circuits
based on Cooper pair boxes, where it can be detected either in shifted dressed
transition frequencies or in pumped charge currents.
