Proposed test of relative phase as hidden variable in quantum mechanics

TL;DR

This paper explores whether the relative phase in quantum mechanics could act as a hidden variable influencing measurement outcomes, proposing conditions and methods to test this hypothesis experimentally.

Contribution

It introduces a framework for testing the role of relative phase as a hidden variable and discusses how to implement such tests in atomic two-state systems.

Findings

Frequency-spectroscopy cannot fix the phase due to uncertainty relations.

Conditions are proposed for measurements at specific phase values.

Implementation strategies for atomic systems are discussed.

Abstract

We consider the possibility that the relative phase in quantum mechanics plays a role in determining measurement outcome and could therefore serve as a "hidden" variable. The Born rule for measurement equates the probability for a given outcome with the absolute square of the coefficient of the basis state, which by design removes the relative phase from the formulation. The value of this phase at the moment of measurement naturally averages out in an ensemble, which would prevent any dependence from being observed, and we show that conventional frequency-spectroscopy measurements on discrete quantum systems cannot be imposed at a specific phase due to a straightforward uncertainty relation. We lay out general conditions for imposing measurements at a specific value of the relative phase so that the possibility of its role as a hidden variable can be tested, and we discuss implementation for the specific case of an atomic two-state system with laser-induced fluorescence for measurement.