Advancing Quantum Metrology in China's Power Grids

In November 2018, during the 26th General Conference on Weights and Measures (CGPM) in Versailles, France, a landmark resolution was adopted to redefine four base units of the International System of Units (SI)(https://www.bipm.org/en/committees/cg/cgpm/26-2018/resolution-1). The kilogram, mole, ampere, and kelvin were redefined in terms of fundamental physical constants: the Planck constant $(h)$ , the Avogadro constant $(N_{\mathrm{A}})$ , the elementary charge $(e)$ , and the Boltzmann constant $(k)$ , respectively. As illustrated in Figure 1(a), the new SI framework defines all seven base units based on fundamental constants, marking a complete transition of metrology into the quantum era. This system has been in effect globally since May 20, 2019, on World Metrology Day.