Is Einstein's equivalence principle valid for a quantum particle?

TL;DR

This paper investigates whether Einstein's equivalence principle, fundamental in classical physics, holds for quantum particles described by wave functions in a Newtonian gravitational setting, and finds a similar level of uniqueness in their motion.

Contribution

The paper extends the validity of Einstein's equivalence principle to quantum particles, showing it constrains their motion similarly to classical particles under gravity.

Findings

Quantum particles obey a form of Einstein's equivalence principle.

The principle determines quantum particle trajectories with high uniqueness.

The results bridge classical and quantum descriptions of gravity.

Abstract

Einstein's equivalence principle in classical physics is a rule stating that the effect of gravitation is locally equivalent to the acceleration of an observer. The principle determines the motion of test particles uniquely (modulo very broad general assumptions). We show that the same principle applied to a quantum particle described by a wave function on a Newtonian gravitational background determines its motion with a similar degree of uniqueness.