Decoherence and the Quantum Theory of the Classical

by Wojciech H. Zurek (Los Alamos National Laboratory, New Mexico)

Tuesday 23 May 2017, 14:30 → 16:30 Europe/Rome

I will describe three insights into the transition from
quantum to classical. After a brief discussion of decoherence I will
give (i) a minimalist (and decoherence-free) derivation of preferred
states. Such pointer states define events (e.g., measurement outcomes)
without appealing to Born's rule (p_k = |\psi_k|^2). Probabilities and (ii) Born’s
rule can be then derived from the symmetries of entangled quantum
states. With probabilities at hand one can analyze information flows
from the system to the environment in course of decoherence. They
explain how (iii) robust “classical reality” arises from the quantum
substrate by accounting for all the symptoms of objective existence of
preferred pointer states of quantum systems through the redundancy
of their records in the environment. Taken together, and in the right
order, these three advances (i)-(iii) elucidate quantum origins of the
classical