Nonclassicality of Light as a Quantifiable Resource for Quantum Metrology

Karol Gietka

Kok Chuan Tan, Hyunseok Jeong, Tyler J. Volkoff +1 more

We discuss the relationship between quantum coherence of finite dimensional systems and nonclassical quantum light. We demonstrate that quantifying the quantum coherence between coherent states always leads to a quantifier of nonclassicality that monotonically decreases under linear optical operations. This allows us to introduce a resource theory of nonclassicality based on linear optics that closely parallels the resource theory of coherence. Finally, we discuss the metrological power of a quantum state, which quantifies how sensitive a quantum state is to displacement operations. It is then shown that the metrological power leads to a nonclassicality monotone.

Hyukjoon Kwon, Kok Chuan Tan, Tyler J. Volkoff +1 more

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. This suggests that metrological power is related to the degree of quantum macroscopicity. Finally, we demonstrate that metrological resources useful for nonclassical displacement sensing tasks can be always converted into a useful resource state for phase sensitivity beyond the classical limit.

V. V. Zemlyanov, N. S. Kirsanov, Michael Romanovich Perelshtein +5 more

Mauro Paternostro, Diogo de Oliveira Soares Pinto

Wenchao Ge, Kurt Jacobs, Saeed Asiri +2 more

This paper presents a measure of single-mode nonclassicality using a quantum resource theory. The authors show that the measure is the first resource-theoretic measure that quantifies the ability of a state to perform useful tasks, e.g., phase sensing in a Mach Zehnder interferometer, which can also be used to lower bound the nonclassicality experimentally