A Precis\~ao da Metrologia Qu\^antica: Limite de Cram\'er-Rao, Informa\c{c}\~ao de Fisher e poss\'iveis Aplica\c{c}\~oes Tecnol\'ogicas

Abstract

This paper explores as didactically as possible the fundamental principles of both classical and quantum metrology, focusing on the Cram\'er-Rao Bound and how it defines the maximum precision in parameter estimation, taking into account noise and the information extracted from the data. We also conduct a detailed study of Fisher Information (both classical and quantum), showing the physical significance of this important figure of merit in metrology. We further discuss how quantum states can surpass classical limits, providing much greater precision. Examples of technological applications include the development of quantum sensors, quantum thermometers, and phase parameter estimation. Finally, we review our results on the estimation of the unknown compression parameter applied to a mode of a quantum Gaussian state.