# Quantum backflow and scattering

## TL;DR

This paper extends the study of quantum backflow to scattering scenarios, demonstrating its universality in short-range potentials and analyzing how reflection and transmission influence this quantum phenomenon.

## Contribution

It introduces the analysis of quantum backflow in scattering contexts, showing its universal presence and bounded spatial extent across various potentials.

## Key findings

- Backflow exists universally in short-range scattering potentials.
- Reflection and transmission affect backflow behavior.
- Backflow is always spatially bounded in these scenarios.

## Abstract

Backflow is the phenomenon that the probability current of a quantum particle on the line can flow in the direction opposite to its momentum. In this article, previous investigations of backflow, pertaining to interaction-free dynamics or purely kinematical aspects, are extended to scattering situations in short-range potentials. It is shown that backflow is a universal quantum effect which exists in any such potential, and is always of bounded spatial extent in a specific sense. The effects of reflection and transmission processes on backflow are investigated, both analytically for general potentials, and numerically in various concrete examples.