Abstract: The history of quantum mechanics is outlined and the fundamental formulas:the Schrdinger equation with the interpretation of the wave function,the Pauli exclusion principle,and the Heisenberg uncertainty principle are presented.The latter is illustrated with sample numerical calculations using this principle.The application of quantum effects in metrology,and present and compare the limits of accuracy and resolution of classical and quantum standards are briey discussed.The role of quantum effects in the new International System of Units are discussed as well.Although quantum effects have a wide range of applications,it is difficult to be understood by the public as it is strongly theoretical,which is reflected in many shortcomings in the 2018 version of SI.Finally,development of quantum metrology are prospected.

Key words: Schrdinger equation, Pauli exclusion principle, Heisenberg uncertainty principle, Planck law, SI system