Logo PTB

Electrical quantum metrology

The Electrical Quantum Metrology Department develops quantum-based methods and systems for the traceability of electric base units to natural constants. Most of the activities are pursued together with external partners within the scope of cooperation projects. These projects aim to further develop and simplify the complex setups to realize the quantum-based units. For one thing, this is beneficial to service and customer-oriented areas of metrology institutes such as PTB; for another, it allows quantum-based standards to be used in industrial calibration laboratories.

[ more ]

The quantum-based realization of the unit of voltage, the volt, is based on the Josephson effect in superconductors. Integrated circuits made of tens of thousands of Josephson junctions allow the generation of DC voltages with "quantum accuracy" and low-frequency AC voltages with amplitudes of up to 10 volts. Josephson junctions driven by high-frequency pulse sequences allow AC voltages to be precisely synthesized with arbitrary wave forms at higher frequencies.

[ more ]

In the new International System of Units (SI), which came into force on 20 May 2019, the unit of electric current, the ampere, is defined based on the value of the elementary charge e. To directly realize this definition, single electrons are transported through a quantum dot that is defined by means of gate electrodes in an extremely narrow conductor. At PTB, components known as single-electron pumps are being developed on the basis of semiconductor materials. Single-electron pumps represent an important contribution to the realization of the SI base unit ampere offer a good potential for developing shot-noise-free electronics and allow fundamental consistency tests in electrical quantum metrology.

[ more ]