Fig. 4: Suggested experiment.
a Suggested experimental setup for measuring the width dynamics of the electronic wave-packet in BSV. An ultrashort photoelectron wavepacket is generated by nanotip photoionization. The width of the photoelectron is subsequently modulated by interaction with a BSV pulse. The relative delay between the ionizing and modulating pulses is scanned using a moving mirror, and the width of the photo-electron wavepacket is measured by a detector as a function of the relative delay. b The width of the photoelectron modulated by a BSV of intensity 3.2e13 W cm−2 and frequency \(\varOmega =0.11\) a.u. The width oscillates sinusoidally with the relative delay, with a frequency of 2Ω, where Ω is the frequency of the pump. The minimum width of the modulated electron is predicted to coalesce with the width of the photoelectron when the BSV arm is blocked (here set to 1 a.u.2). c The visibility (contrast) of the modulation is predicted to increase linearly with the BSV intensity
