Abstract

Recent experimental claims of an observation of a Schroedinger’s cat state indicate the importance of macroscopic quantal signatures of superposition states. I propose an experiment which would definitely rule out ANY classical explanation. The experiment involves simultaneous measurements performed on two spatially separated macroscopic systems at locations A and B respectively. At each location there are two field modes a_ and a₊ and b_ and b₊, representing orthogonally polarised modes with a macroscopic number of particles. At each location a measurement is made with a polariser which transmits light polarised at angle θ, represented by mode c₊ = â+ cos θ /2 +a_ sin θ /2, and reflects light orthogonally polarised, represented by mode c_ = â₊ sin θ /2–â_ cos θ /2. We have similar definitions $d_{+}={\widehat{b}}_{+}\cos \varphi /2+{\widehat{b}}_{-}\sin \varphi /2$ and $d_{-}={\widehat{b}}_{+}\sin \varphi /2-{\widehat{b}}_{-}\cos \varphi /2$ for transmitted and reflected beams at B, relating to a measurement of polarisation at angle ϕ. The final stage of the measurement is the detection of the fields c_± and d_± to determine the total number, N₊, of particles in an up, or “+”, direction and the total number of particles, N_, in the down, or “-”, direction $\left(N_{+}=c^{†}+c_{+}\text{and }{N}_{-}=c_{-}^{†}{c}_{-}\right)$. I assign the result of the measurement a value $S_{\theta }^A=+1$ if $N_{+}\ge N_{-}$ and $S_{\theta }^A=-1$ otherwise, and similarly I define $S_{\varphi }^B$ at B

© 2000 IEEE