Macroscopic Schrödinger Cat Resistant to Particle Loss and Local Decoherence

Abstract

The Schrödinger cat state plays a crucial role in quantum theory, and has important fundamental as well as technological implications, ranging from quantum measurement theory to quantum computers. The power of the potential implications of the cat state lies in the quantum coherence, as measured by the degree of entanglement, between its microscopic and macroscopic sectors. We show that in contrast to other cat states, it is possible to choose the states of the macroscopic sector in a way that the resulting cat state, which we term as the W-cat state, has quantum coherence that is resistant to the twin effects of environmental noise -- local decoherence on all the particles and loss of a finite fraction of its particles. The states of the macroscopic sector of the W-cat state are macroscopically distinct in terms of their violation of Bell inequality.