Two-color coherent control of femtosecond above-threshold photoemission from a tungsten nanotip

TL;DR

This paper demonstrates precise control of electron emission from a tungsten nanotip using two synchronized laser pulses, achieving high contrast modulation by exploiting quantum interference effects within femtoseconds.

Contribution

It introduces a method for coherent control of above-threshold photoemission from a solid-state nanoemitter using phase-tuned dual laser pulses, with detailed experimental and simulation analysis.

Findings

Electron emission contrast reaches up to 94%.

Photoemission occurs within 10 femtoseconds.

All photon orders are similarly affected by phase control.

Abstract

We demonstrate coherent control of multiphoton and above-threshold photoemission from a single solid-state nanoemitter driven by a fundamental and a weak second harmonic laser pulse. Depending on the relative phase of the two pulses, electron emission is modulated with a contrast of the oscillating current signal of up to 94%. Electron spectra reveal that all observed photon orders are affected simultaneously and similarly. We confirm that photoemission takes place within 10 fs. Accompanying simulations indicate that the current modulation with its large contrast results from two interfering quantum pathways leading to electron emission.