Entanglement and maximal violation of the CHSH inequality in a system of two spins j: a novel construction and further observations

Abstract

We study the CHSH inequality for a system of two spin $j$ particles, for generic $j$. The CHSH operator is constructed using a set of unitary, Hermitian operators $\left\{ A_{1},A_{2},B_{1},B_{2}\right\} $. The expectation value of the CHSH operator is analyzed for the singlet state $\left|\psi_{s}\right\rangle $. Being $\left|\psi_{s}\right\rangle $ an entangled state, a violation of the CHSH inequality compatible with Tsirelson's bound is found. Although the construction employed here differs from that of [1], full agreement is recovered.