Shaping Long-lived Electron Wavepackets for Customizable Optical Spectra

TL;DR

This paper introduces a method to shape electron wavepackets as superpositions of continuum states, enabling customizable optical spectra and potentially expanding the energy range and versatility of electron-based emitters.

Contribution

It proposes a novel approach to shape electron wavepackets in the continuum, allowing for tunable optical emission spectra across a broad energy range.

Findings

Shaping length affects diffraction lifetime and spatial spread of wavepackets.

Wavepacket shape influences spontaneous radiative transition rates.

Diffraction lifetime limits radiative capture rate.

Abstract

Electrons in atoms and molecules are versatile physical systems covering a vast range of light-matter interactions, enabling the physics of Rydberg states, photon-photon bound states, simulation of condensed matter Hamiltonians, and quantum sources of light. A limitation on the versatility of such electronic systems for optical interactions would appear to arise from the discrete nature of the electronic transitions and from the limited ionization energy, constraining the energy scale through which the rich physics of bound electrons can be accessed. In this work, we propose the concept of shaping spatially confined electron wavepackets as superpositions of extended states in the ionization continuum. These wavepackets enable customizable optical emission spectra transitions in the eV-keV range. We find that the specific shaping lengthens the diffraction lifetime of the wavepackets in exchange for increasing their spatial spreads. Finally, we study the spontaneous radiative transitions of these excited states, examining the influence of the wavepacket shape and size on the radiation rate of the excited state. We observe that the rate of radiative capture is primarily limited by the diffraction lifetime of the wavepacket. The approach proposed in this work could have applications towards developing designer emitters at tunable energy and length scales, potentially bringing the physics of Rydberg states to new energy scales and extending the range and versatility of emitters that can be developed using shaped electrons.