Nonclassicality of The Kirkwood-Dirac Quasiprobability Distribution via Quantum Modification Terms

2024.2.22 17:00 N613

We suggest a Kirkwood-Dirac (KD) nonclassicality measure based on the two quantum modification terms in the quasiprobability distribution, which refines the quantification of KD nonclassicality in the sense that even for real and nonnegative KD distribution, its quantum modification terms can still exist, resulting in a nonvanishing KD nonclassicality. As an illustration, we analyze the KD nonclassicality of the positive KD distribution in the postselected metrology scheme [S. Das, S. Modak, and M. N. Bera, Phys. Rev. A 107, 042413 (2023)], which provides interpretation on the source of quantum advantages. We also give an upper bound on the KD nonclassicality measure and offer an easily verifiable sufficient condition for nonvanishing KD nonclassicalit.