Macrorealism from entropic Leggett-Garg inequalities

Abstract

We formulate entropic Leggett-Garg inequalities, which place constraints on the statistical outcomes of temporal correlations of observables. The information theoretic inequalities are satisfied if macrorealism holds. We show that the quantum statistics underlying correlations between time-separated spin component of a quantum rotor mimics that of spin correlations in two spatially separated spin-s particles sharing a state of zero total spin. This brings forth the violation of the entropic Leggett-Garg inequality by a rotating quantum spin-s system in a similar manner as does the entropic Bell inequality [ S. L. Braunstein and C. M. Caves Phys. Rev. Lett. 61 662 (1988)] by a pair of spin-s particles forming a composite spin singlet state.