On the theory of quantum measurement

TL;DR

This paper addresses the quantum measurement problem by proposing a new objective condition for state reduction based on separation status and thermodynamic mixing, supported by a model of real measurement.

Contribution

It introduces the concept of separation status and TPOV measures, providing a testable theory for when quantum state reduction occurs.

Findings

Disturbance from identical particles makes POV measures non-measurable.

TPOV measures are measurable if systems have separation status.

Thermodynamic mixing in detectors is an objective condition for state reduction.

Abstract

The notion of state reduction employed by the standard quantum theory of measurement is difficult to accept for two reasons: It leaves open where and when the reduction takes place and it does not give any objective conditions under which the reduction occurs. Some recently published ideas on this problem are developed an improved. The disturbance of measurement due to identical particles in the environment is shown to make any POV measure non-measurable. Truncated POV (TPOV) measures are introduced that can be measurable if object systems satisfy the additional requirement of having separation status. The separation status is generalised from domain of space to domain of phase space. Starting from the previously introduced distinction between ancillas and detectors, further study of experiments suggests that a thermodynamic mixing within a detector and the consequent loss of separation status is the objective condition for the occurrence of the state reduction. The conjecture is simple, specific and testable. The theory is illustrated by a model of a real measurement.