Solving the Detection Problem

We present a solution of the detection problem based on nonlocal properties of the entangled pre-detection state and insights from the RTO experiments (Chap. 9 ). We define “detection” and review von Neumann’s derivation of the pre-detection state. This entangled state provides the nonlocal properties required for collapse and detection. We review Schrodinger’s concerns about quantum superposition and detection as expressed in his 1935 paper involving a cat that seems “smeared” (superposed) between life and death. In 1927, Einstein presented a thought experiment demonstrating that Schrodinger’s equation entails nonlocal wave function collapse. This was a key insight. Seven “proofs” of the insolubility of the detection problem are irrelevant because they assume the pre-detection state should be a non-entangled (hence local) mixture of the possible outcomes. Such a local solution is impossible. The RTO experiments (Chap. 9 ) provide new insight. Contrary to previous opinions, the pre-detection state is not a paradoxical superposition of detector states. This state superposes only correlations, not states. For example, a live cat is correlated with an undecayed nucleus, AND a dead cat is correlated with a decayed nucleus. Furthermore, the pre-detection state predicts a single definite outcome. Thus, a proper understanding of nonlocal interference resolves the detection problem.