1212.3245 (Wojciech H. Zurek)

Actionable Information, Repeatability, Quantum Jumps, and the Wavepacket
Collapse    [PDF]

Wojciech H. Zurek

Unknown quantum state cannot be discovered as the measured system is re-prepared -- it jumps into an eigenstate of the measured observable. This impossibility to find out a quantum state and other symptoms of the wavepacket collapse follow (as was recently demonstrated for pure states of measured systems) from unitarity (that doesn't, however, allow for a literal collapse) and from the repeatability of measurements. Here we extend this result to mixtures and decohering systems. This accounts for quantum jumps in a macroscopic and open (but ultimately quantum) apparatus.

View original: http://arxiv.org/abs/1212.3245