  We propose a method to obtain Floquet states---also known as light-induced
states---and their quasi-energies from real-time wavefunctions without solving
the Floquet equation. This is useful for the analysis of various phenomena in
time-dependent quantum dynamics if the Hamiltonian is not strictly periodic, as
in short laser pulses, for instance. There, the population of the Floquet
states depends on the pulse form and is automatically contained in the
real-time wavefunction but not in the standard Floquet approach. Several
examples in the area of intense laser-atom interaction are exemplarily
discussed: (i) the observation of even harmonics for an inversion-symmetric
potential with a single bound state; (ii) the dependence of the population of
Floquet states on (gauge) transformations and the emergence of an invariant,
observable photoelectron spectrum; (iii) the driving of resonant transitions
between dressed states, i.e., the dressing of dressed states, and (iv) spectral
enhancements at channel closings due to the ponderomotive shift of
above-threshold ionization peaks.
