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arXiv · 2205.11161

Quantum interference visibility spectroscopy in two-color photoemission from tungsten needle tips

Ang Li·Yiming Pan·Philip Dienstbier·Peter Hommelhoff
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Abstract

When two-color femtosecond laser pulses interact with matter, electrons can be emitted through various multiphoton excitation pathways. Quantum interference between these pathways gives rise to a strong oscillation of the photoemitted electron current, experimentally characterized by its visibility. In this work, we demonstrate two-color visibility spectroscopy of multi-photon photoemission from a solid-state nanoemitter. We investigate the quantum pathway interference visibility over an almost octave-spanning wavelength range of the fundamental femtosecond laser pulses and their second-harmonic. The photoemission shows a high visibility of 90% +/- 5%, with a remarkably constant distribution. Furthermore, by varying the relative intensity ratio of the two colors, we find that we can vary the visibility between 0 and close to 100%. A simple but highly insightful theoretical model allows us to explain all observations, with excellent quantitative agreements. We expect this work to be universal to all kinds of photo-driven quantum interference, including quantum control in physics, chemistry and quantum engineering.

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Ang Li, Yiming Pan, Philip Dienstbier, Peter Hommelhoff. 2022-05-23. Quantum interference visibility spectroscopy in two-color photoemission from tungsten needle tips. https://doi.org/10.1103/physrevlett.126.137403

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