A Dynamic 'Double Slit' Experiment in a Single Atom

TL;DR

This paper demonstrates a single-atom double-slit experiment using photo-ionization of Rubidium, showing how internal atomic states can produce observable interference patterns with tunable pathways, supported by a quantum model.

Contribution

It introduces a novel single-atom double-slit setup with dynamic control over interference pathways, combining experimental realization with theoretical modeling.

Findings

Successful observation of two-path interference in a single atom

Tunable interference via laser frequency and intensity adjustments

Quantum model accurately predicts experimental results

Abstract

A single-atom 'double-slit' experiment is realized by photo-ionizing Rubidium atoms using two independent low power lasers. The photoelectron wave of well-defined energy recedes to the continuum either from the 5P or 6P states in the same atom, resulting in two-path interference imaged in the far field using a photoelectron detector. Even though the lasers are independent and not phase locked, the transitions within the atom impart the phase relationship necessary for interference. The experiment is designed so that either 5P or 6P states are excited by one laser, before ionization by the second beam. The measurement cannot determine which excitation path is taken, resulting in interference in wave-vector space analogous to Young's double-slit studies. As the lasers are tunable in both frequency and intensity, the individual excitation-ionization pathways can be varied, allowing dynamic control of the interference term. Since the electron wave recedes in the Coulomb potential of the residual ion, a quantum model is used to capture the dynamics. Excellent agreement is found between theory and experiment.