Time-frequency Domain Analogues of Phase Space Sub-Planck Structures
  We present experimental data of the frequency resolved optical gating (FROG) measurements of light pulses revealing interference features corresponding to sub-Planck structures in phase space. For superpositions of pulses a small, sub-Fourier shift in the carrier frequency leads to a state orthogonal to the initial one, although in the representation of standard time-frequency distributions these states seem to have a nonvanishing overlap. 
Ludmila Praxmeyer, Piotr Wasylczyk, Czeslaw Radzewicz, Krzysztof   Wodkiewicz