### A boost for quantum reality

##### May 9, 2012 | Source: Nature News

In a controversial paper in *Nature Physics*, theorists claim they can prove that wavefunctions — the entity that determines the probability of different outcomes of measurements on quantum-mechanical particles — are real states.

The paper is thought by some to be one of the most important in quantum foundations in decades. The authors say that the mathematics leaves no doubt that the wavefunction is not just a statistical tool, but rather, a real, objective state of a quantum system.

Matt Leifer, a physicist at University College London who works on quantum information, says that the theorem tackles a big question in a simple and clean way. He also says that it could end up being as useful as Bell’s theorem, which turned out to have applications in quantum information theory and cryptography.

But it’s incompatible with quantum mechanics, so the theorem also raises a deeper question: could quantum mechanics be wrong?

Ref.: Matthew F. Pusey, Jonathan Barrett, Terry Rudolph, On the reality of the quantum state, *Nature Physics*, 2012, DOI: 10.1038/nphys2309

Ref.: Matthew F. Pusey, Jonathan Barrett, Terry Rudolph, On the reality of the quantum state, 2011, arXiv:1111.3328v2