Experiment-friendly formulation of quantum backflow

Quantum backflow is usually understood as a quantum interference phenomenon where probability current of a quantum particle points in the opposite direction to particle's momentum. Here, we quantify the amount of quantum backflow for arbitrary momentum distributions, paving the way towards its experimental verification. We give examples of backflow in gravitational and harmonic potential, and discuss experimental procedures required for the demonstration using atomic gravimeters. Such an experiment would show that the probability of finding a free falling particle above initial level could grow for suitably prepared quantum state with most momentum downwards.

Automated summary

Quantum backflow is a quantum interference phenomenon where the probability current of a quantum particle points opposite to its momentum. This study quantifies the amount of quantum backflow for arbitrary momentum distributions, providing a framework for experimental verification. Examples of backflow in gravitational and harmonic potential are given, along with discussions on the necessary experimental procedures for demonstration using atomic gravimeters.