1205.1439 (Luchen Hardy)

Are quantum states real?    [PDF]

Luchen Hardy

In this paper we give a new argument for the reality of the wavefunction. We consider theories in which reality is described by some underlying variables. Each value of these variables can take represents an ontic state (a particular state of reality). The preparation of a quantum state corresponds to a distribution over the ontic states. Using three basic assumptions, we will show that the distributions over ontic states corresponding to distinct pure states are non-overlapping. This means that we can deduce the quantum state from a knowledge of the ontic state. Hence we can claim that the quantum state is a real thing (it is written into the underlying variables that describe reality). The key assumption we use in this proof is ontic indifference - that quantum transformations that do not effect a given pure quantum state can be implemented in such a way that they do not effect the ontic states in the support of that state. This argument in this paper is different from the recent proof of Pusey, Barrett, and Rudolph. It uses a different key assumption and it pertains to a single copy of the system in question.

View original: http://arxiv.org/abs/1205.1439