An inverse scattering problem for short-range systems in a time-periodic   electric field
  We consider the time-dependent Hamiltonian $H(t)= {1 \over 2} p^2 -E(t) \cdot x + V(t,x)$ on $L^2(R^n)$, where the external electric field $E(t)$ and the short-range electric potential $V(t,x)$ are time-periodic with the same period. It is well-known that the short-range notion depends on the mean value $E\_0$ of the external field. When $E\_0=0$, we show that the high energy limit of the scattering operators determines uniquely $V(t,x)$. In the other case, the same result holds in dimension $n \geq 3$ for generic sghort-range potentials. In dimension 2, one has to assume a stronger decay on the electric potential. 
Fran\c{c}ois Nicoleau (LMJL)