Abstract
We predict that the phase-dependent error distribution of locally unentangled quantum states directly affects quantum parameter estimation accuracy. Therefore, we employ the displaced squeezed vacuum (DSV) state as a probe state and investigate an interesting question of the phase-sensitive nonclassical properties in DSV's metrology. We found that the accuracy limit of parameter estimation is a function of the phase-sensitive parameter φ -θ /2 with a period π . We show that when φ -θ /2 ∈ [ kπ/2,3kπ /4) ( k∈ Z), we can obtain the accuracy of parameter estimation approaching the ultimate quantum limit through using the DSV state with the larger displacement and squeezing strength, whereas φ -θ /2 ∈ (3kπ /4,kπ ] ( k∈ Z) , the optimal estimation accuracy can be acquired only when the DSV state degenerates to a squeezed-vacuum state.