Quantum Darwinism Requires an Extra-Theoretical Assumption of Encoding Redundancy

Abstract

Observers restricted to the observation of pointer states of apparatus cannot conclusively demonstrate that the pointer of an apparatus $\mathcal{A}$ registers the state of a system of interest S without perturbing S. Observers cannot, therefore, conclusively demonstrate that the states of a system S are redundantly encoded by pointer states of multiple independent apparatus without destroying the redundancy of encoding. The redundancy of encoding required by quantum Darwinism must, therefore, be assumed from outside the quantum-mechanical formalism and without the possibility of experimental demonstration.