Ultrafast switching of photoemission electron through quantum pathways interference in metallic nanostructure.

Abstract

The localized photoemission electron originating from the plasmonic "hot spots" in a metallic bowtie nanostructure can be separately switched on and off by adjusting the relative time delay between two orthogonally polarized laser pulses. The demonstrated femtosecond timing, nanometric spatial switching of multiphoton photoemission results from the interference of quantum pathways. Energy resolved measurement of the photoemission electrons further shows that the quantum pathway interference mechanism applies to control all the liberated electrons. The experimental results also show that the probability of electron emission through the quantum pathways from a plasmonic hot spot is determined by the localized emission response to the two incident laser pulses. These findings are of importance for controlling photoemission in ultrahigh spatiotemporal resolution in metallic plasmonic nanostructures.