Quantum information can be encoded in the quantum electromagnetic field in various ways. For example, non-classical superpositions of photon number states, such as Schrödinger cat states, provide one form of encoding. Alternatively, the degrees of freedom of single photons, such as polarization, can be used to encode qubits. An intriguing question arises: is there a way to relate these two types of quantum information encoding—one based on particle statistical properties and the other on mode/particle entanglement? Can one be mapped onto the other while adhering to physical principles, such as energy conservation, or informational principles, such as providing the same advantage over classical encodings? Our goal is to design common quantifiers for these quantum optical encodings. During this internship, we will address this issue in the particular field of quantum metrology, which aims to achieve quantum-enhanced precision in parameter estimation. Using single photons in different frequency modes results in the same type of precision enhancement as that achieved with photon number state superpositions. Our objective is to develop a unified formalism that describes all quantum optical encodings capable of achieving quantum-enhanced precision.