Testing the postulates of quantum mechanics with coherent states of light and homodyne detection

TL;DR

This paper conducts a novel experimental test of quantum mechanics postulates using coherent light states and homodyne detection in a three-arm interferometer, providing tighter bounds on third-order interference and the nature of quantum complexity.

Contribution

It introduces a new experimental setup with coherent states in a three-arm interferometer to test foundational quantum postulates, expanding the scope of previous tests.

Findings

Third order interference bounded to κ = 0.002 ± 0.004

Peres parameter F = 1.0000 ± 0.0003, consistent with complex quantum mechanics

Test of Glauber's optical coherence theory

Abstract

Quantum mechanics has withstood every experimental test thus far. However, it relies on ad-hoc postulates which require experimental verification. Over the past decade there has been a great deal of research testing these postulates, with numerous tests of Born's rule for determining probabilities and the complex nature of the Hilbert space being carried out. Although these tests are yet to reveal any significant deviation from textbook quantum theory, it remains important to conduct such tests in different configurations and using different quantum states. Here we perform the first such test using coherent states of light in a three-arm interferometer combined with homodyne detection. Our proposed configuration requires additional assumptions, but allows us to use quantum states which exist in a larger Hilbert space compared to previous tests. For testing Born's rule, we find that the third order interference is bounded to be $\kappa$ = 0.002 $\pm$ 0.004 and for testing whether quantum mechanics is complex or not we find a Peres parameter of F = 1.0000 $\pm$ 0.0003 (F = 1 corresponds to the expected complex quantum mechanics). We also use our experiment to test Glauber's theory of optical coherence.