Characterizing multilevel coherence via the fidelity
Mengjia Zhang, Yan Hong, Xianfei Qi
Abstract Quantum coherence originates from the principle of quantum superposition, and multilevel quantum coherence contributes to a more comprehensive understanding of the principle of quantum superposition. In this paper, we investigate multilevel coherence through fidelity. We define a quantity F a ( ρ , σ ) through fidelity and prove that this quantity satisfies several important properties. Based on this quantity F a ( ρ , σ ) , we define an indicator M a k ( ρ ) to characterize multilevel coherence, and prove that this indicator satisfies non-negativity, convexity, monotonicity (non-increasing under ( k − 1 ) -coherence-preserving operation), and subadditivity.
Laser Physics Letters•May 1, 2026•0 citations