# Time-energy filtering of single electrons in ballistic waveguides

## TL;DR

This paper develops a quantum mechanical model for single-electron scattering in ballistic waveguides with time-dependent potentials, enabling better characterization and control of electron wave packets for quantum technologies.

## Contribution

It provides a detailed quantum scattering framework incorporating time-energy distributions and supports quantum tomography methods for electron characterization.

## Key findings

- Electrons are described using a modified Wigner quasiprobability distribution.
- The model simplifies under linear time-dependent potentials, allowing semiclassical interpretation.
- Results facilitate experimental measurement of electron time-energy distributions.

## Abstract

Characterizing distinct electron wave packets is a basic task for solid-state electron quantum optics with applications in quantum metrology and sensing. A important circuit element for this task is a non-stationary potential barrier than enables backscattering of chiral particles depending on their energy and time of arrival. Here we solve the quantum mechanical problem of single-particle scattering by a ballistic constriction in an fully depleted quantum Hall system under spatially uniform but time-dependent electrostatic potential modulation. The result describes electrons distributed in time-energy space according to a modified Wigner quasiprobability distribution and scattered with an energy-dependent transmission probability that characterizes constriction in the absence of modulation. Modification of the incoming Wigner distribution due to external time-dependent potential simplifies in case of linear time-dependence and admits semiclassical interpretation. Our results support a recently proposed and implemented method for measuring time and energy distribution of solitary electrons as a quantum tomography technique, and offer new paths for experimental exploration of on-demand sources of coherent electrons.