Leggett-Garg inequalities with deformed Pegg-Barnett phase observables

Abstract

We investigate the Leggett-Garg inequalities (LGIs) for a boson system whose observables are given by deforming the Pegg-Barnett phase operators. We consider two observables and show that the quantum Fourier transform is useful in the realization of the required measurements. Deriving explicit forms for the LGIs using the coherent state $|\ensuremath{\alpha}\ensuremath{\rangle}$ as the initial state, we explore the regimes where they are violated when the time difference between observations of the phase operators is varied. We show that the system remains nonclassical in the large amplitude limit without dissipation; however, with dissipation, our violation diminishes rapidly.