I don't know about links to computational complexity, but in the many worlds interpretation the "classical approximation" is explained by "quantum decoherence".

I don't know about links to computational complexity, but in the many worlds interpretation the "classical approximation" is explained by "quantum decoherence". 1: http://en.wikipedia.org/wiki/Quantum_decoherence http://en.wikipedia.org/wiki/Quantum_decoherence 2: http://lesswrong.com/lw/pp/decoherence/ http://lesswrong.com/lw/pp/decoherence/