Quantum interference between fundamentally different processes is enabled by shaped input wavefunctions

TL;DR

This paper introduces a framework demonstrating how shaped input wavefunctions enable quantum interference between fundamentally different processes, leading to novel interactions between electrons and photons with potential applications in quantum control.

Contribution

The work provides a general theoretical framework showing how wavefunction shaping enables quantum interference between diverse processes, including free and bound electron interactions, which was previously not understood.

Findings

Destructive quantum interference can eliminate the zero-loss peak in electron-light interactions.

Quantum interference between free electrons and atomic emission can occur over large distances.

Wavefunction shaping enhances the versatility of light-matter quantum interactions.

Abstract

We present a general framework for quantum interference (QI) between multiple, fundamentally different processes. Our framework reveals the importance of shaped input wavefunctions in enabling QI, and predicts unprecedented interactions between free electrons, bound electrons, and photons: (i) the vanishing of the zero-loss peak by destructive QI when a shaped electron wavepacket couples to light, under conditions where the electron's zero-loss peak otherwise dominates; (ii) QI between free electron and atomic (bound electron) spontaneous emission processes, which can be significant even when the free electron and atom are far apart, breaking the common notion that electron and atom must be close by to significantly affect each other's processes. Our work shows that emerging quantum waveshaping techniques unlock the door to greater versatility in light-matter interactions and other quantum processes in general.