Definition of quantum decoherence

Question

I am writing a short essay on many worlds interpretation and trying to define quantum decoherence in a sentence. thanks in advance.

Answer 1

The process whereby the quantum-mechanical state of any macroscopic system is rapidly correlated with that of its environment in such a way that no measurement on the system alone (without a simultaneous measurement of the complete state of the environment) can demonstrate any interference between two quantum states of the system.