Nonclassicality as a Quantifiable Resource for Quantum Metrology

Understand

We establish the nonclassicality of continuous-variable states as a resource for quantum metrology.

• Based on the quantum Fisher information of multimode quadratures, we introduce the metrological power as a measure of nonclassicality with a concrete operational meaning of displacement sensitivity beyond the classical limit.
• This measure belongs to the resource theory of nonclassicality, which is nonincreasing under linear optical elements.
• Our Letter reveals that a single copy, highly nonclassical quantum state is intrinsically advantageous when compared to multiple copies of a quantum state with moderate nonclassicality.