Local model of a qubit in the interferometric setup

TL;DR

This paper presents a classical simulation model of a qubit in interferometric setups that reproduces quantum predictions using local interactions and hidden variables, challenging the notion of inherent quantum non-locality.

Contribution

The authors develop a classical, local model with stochastic gates and particles that replicates quantum interferometric behavior, including paradoxes and non-local effects.

Findings

Model reproduces quantum predictions operationally indistinguishable from true qubits.

Non-local effects are shown to be epistemic, arising from incomplete knowledge.

Classical simulation uses real particles and ghosts with local interactions.

Abstract

We consider a typical realization of a qubit as a single particle in two-path interferometric circuits built from phase shifters, beam splitters and detectors. This framework is often taken as a standard example illustrating various paradoxes and quantum effects, including non-locality. In this paper we show that it is possible to simulate the behaviour of such circuits in a classical manner using stochastic gates and two kinds of particles, real ones and ghosts, which interact only locally. The model has built-in limited information gain and state disturbance in measurements which are blind to ghosts. We demonstrate that predictions of the model are operationally indistinguishable from the quantum case of a qubit, and allegedly 'non-local' effects arise only on the epistemic level of description by the agent whose knowledge is incomplete due to the restricted means of investigating the system.