An exploration of the limits of control using quantum superpositions

TL;DR

This paper investigates how quantum superpositions challenge classical causality and the principle of least action, revealing fundamental limits of control in quantum systems.

Contribution

It demonstrates that quantum interference can violate the principle of least action, offering new insights into the fundamental differences between quantum and classical physics.

Findings

Quantum interference between non-orthogonal states challenges classical causality.

The proof shows a failure of the principle of least action in quantum regimes.

Implications for fundamental physics and the limits of control are discussed.

Abstract

Quantum interferences between non-orthogonal states are the best approximation of a joint realization of the non-commuting physical properties represented by the two states. As I have shown recently, such interferences can be used to demonstrate that quantum physics deviates from classical causality in the limit of small action. Here, I point out that this proof constitutes a failure of the principle of least action and consider possible implications for our understanding of fundamental physics.