Ultrafast all-optical modulation of spatially structured photons

Manipulating the structure of single photons in the ultrafast domain is enabling new quantum information processing technologies. At the picosecond timescale, quantum information can be processed before decoherence can occur. In this work, we study the capabilities of few-mode cross-phase modulation via the optical Kerr effect, using ultrafast pulses. We observe a significant modulation in the spatial mode of structured photons on timescales $\le 1.3$~ps.