  Spectral- and time- multiplexing are currently explored to generate large
multipartite quantum states of light for quantum technologies. In the
continuous variable approach, the deterministic generation of large entangled
states demands the generation of a large number of squeezed modes. Here, we
demonstrate the simultaneous generation of 21 squeezed spectral modes at 156
MHz. We exploit the full repetition rate and the ultrafast shaping of a
femtosecond light source to combine, for the first time, frequency- and time-
multiplexing in multimode squeezing. This paves the way to the implementation
of multipartite entangled states that are both scalable and fully
reconfigurable.
