Thursday, October 09, 2014

Are Weak Measurements Classical?

I've pointed out at least one experiment that employ the weak measurement technique, and the outcome somehow corresponded to the Bohm pilot wave picture.

Now comes a new theoretical paper that questioned the whole principal of weak measurements in the first place. The paper went back all the way to the paper by Aharonov et al. that first proposed such a technique. The new paper quetioned whether weak measurement actually is measuring the quantum properties, or weather it is actually just measuring the classical outcome.

"Weak values do not seem to be a property of the system in any way," says Ferrie. He and Combes claim that while the idea of weakly measuring a system is fine, making pre- and post-selections is akin to having a set of data and just favouring a subset of it – meaning that any measurement made is a ather than a consequence of classical statistics rather than a physical property of the system. "So long as there is some co-relation between the second [weak measurement] and third [post-selection] steps, you will have an anomalous weak value," says Ferrie. But such a correlation would mean that the original quantum system being measured is no longer sound.

This is certainly interesting and it will be fascinting to see how the proponents of weak measurements respond to this.

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