The International System of Units, the SI, provides the foundation for all measurements in science, engineering, economics, and society. The SI has been fundamentally revised in 2019. The new SI is a universal and highly stable unit system based on invariable constants of nature. Its implementation rests on quantum metrology and quantum standards, which base measurements on the manipulation and counting of single quantum objects, such as electrons, photons, ions, and flux quanta. This book explains and illustrates the new SI, its impact on measurements, and the quantum metrology and quantum technology behind it. The book is based on the book ?Quantum Metrology: Foundation of Units and Measurements? by the same authors. From the contents:-Measurement-The SI (Système International d?Unités)-Realization of the SI Second: Thermal Beam Cs Clock, Laser Cooling, and the Cs Fountain Clock -Flux Quanta, Josephson Effect, and the SI Volt -Quantum Hall Effect, the SI Ohm, and the SI Farad -Single-Charge Transfer Devices and the SI Ampere -The SI Kilogram, the Mole, and the Planck constant -The SI Kelvin and the Boltzmann Constant -Beyond the present SI: Optical Clocks and Quantum Radiometry -Outlook

ForewordPrefaceList of AbbreviationsINTRODUCTIONBASICSMeasurementThe SI (Système International d'Unités)LASER COOLING, ATOMIC CLOCKS, AND THE SECONDTechniques for Laser CoolingThe Cs-Fountain ClockOptical ClocksSUPERCONDUCTIVITY, JOSEPHSON EFFECT, AND FLUX QUANTAJosephson Effect and Quantum Voltage StandardsFlux Quanta and Superconducting Quantum Interference DevicesQUANTUM HALL EFFECTBasic Physics of Three- and Two Dimensional SemiconductorsTwo-Dimensional Electron Systems in Real SemiconductorsThe Hall EffectQuantum Hall Resistance StandardsSINGLE-CHARGE TRANSFER DEVICES AND THE NEW AMPEREBasic Physics of Single-Electron TransportQuantized Current SourcesConsistency Tests: Quantum Metrology TrianglePLANCK CONSTANT, THE NEW KILOGRAM, AND THE MOLEThe Avogadro ExperimentThe Watt Balance ExperimentThe Mole, Unit of Amount of SusbstanceBOLTZMANN CONSTANT AND THE NEW KELVINPrimary ThermometersRealization and Disseminiation of the New KelvinSINGLE-PHOTON METROLOGY AND QUANTUM RADIOMETRYSingle-Photon SourcesSingle-Photon DetectorsMetrological Challenges