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Quantum reality theorem

Quantum reality theorem

Quantum state cannot be interpreted statistically

Pusey, M., Barrett, J. & Rudolph, Terry, Imperial College London

arXiv: 1111.3328v1 [quant-ph] 14 Nov 2011 and nature.com

Keywords: Wave function collapse, quantum state

In this preprint posting, the authors claim to have shown by their theorem that the view that quantum states are only mathematical abstractions (referred to as the statistical interpretation) is inconsistent with the predictions of quantum theory, and that therefore quantum states are real physical states.

The theorem indicates that quantum states in an experiment must 'know' what state they have been prepared in, i.e. they must be physical systems, or an experiment will have results not predicted by quantum mechanics. They also claim that it is feasible for the theorem to be tested by experiment. Against this it should be noted that some commentators on nature.com argue that there are errors in the authors' work.

Schrödinger originally conceived the wave function as a physical state, but others soon argued that the wave function was not physical, or was merely a convenient fiction, a calculational procedure, or an encoding of experimenters limited information. P. The view that the wave function was only a mathematical abstraction was the basis of the Copenhagen interpretation of quantum theory that dominated thinking through much of the 20^th century. Support for the Copenhagen interpretation was eroded in the latter part of the 20^th century, but the idea of the wave function as a mathematical abstraction has more recently been given a new lease of life by quantum information, which views the wave function as abstract information.

If the authors' theorem was to be vindicated it would not merely discredit quantum information theory but conclude the debate of nearly a century as to whether the quantum wave function was a physical reality. Clearly, this has crucial implications for Penrose and similar theories that look to the reality of the wave function to open physical access to a fundamental level of the universe.