Emergence of the pointer basis through the dynamics of correlations

TL;DR

This paper investigates how the classical pointer basis emerges suddenly during quantum measurements due to correlations and decoherence, highlighting a non-asymptotic transition with experimental validation.

Contribution

It formalizes the emergence of the pointer basis in decohering quantum measurement apparatuses and demonstrates this phenomenon experimentally.

Findings

Correlations exhibit a sudden transition from decay to a constant level.

Pointer basis emergence occurs non-asymptotically during decoherence.

Experimental validation with polarization entangled photons confirms the theory.

Abstract

We use the classical correlation between a quantum system being measured and its measurement apparatus to analyze the amount of information being retrieved in a quantum measurement process. Accounting for decoherence of the apparatus, we show that these correlations may have a sudden transition from a decay regime to a constant level. This transition characterizes a non-asymptotic emergence of the pointer basis, while the system-apparatus can still be quantum correlated. We provide a formalization of the concept of emergence of a pointer basis in an apparatus subject to decoherence. This contrast of the pointer basis emergence to the quantum to classical transition is demonstrated in an experiment with polarization entangled photon pairs.