On the role of entanglement in Schrödinger's cat paradox

Abstract

In this paper we re-investigate the core of Schrödinger's "cat paradox". We argue that one has to distinguish clearly between superpositions of macroscopic cat states 〉 + 〉 and superpositions of entangled states , ↑〉 + , ↓〉 which comprise both the state of the cat ( =alive, =dead) and the radioactive substance (↑=not decayed, ↓=decayed). It is shown, that in the case of the cat experiment recourse to decoherence or other mechanisms is not necessary in order to explain the absence of macroscopic superpositions. Additionally, we present modified versions of two quantum optical experiments as experimenta crucis. Applied rigorously, quantum mechanical formalism reduces the problem to a mere pseudo-paradox. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2008.