The watt balance Mark II of the Federal Institute of Metrology METAS is ready to start the measurement of the Planck constant. After an intensive conception phase, the different modules of the experiment have been designed, realized and characterized in close collaboration with external partners. Beside an overview of the experimental setup and some results, the present paper shows also theoretical aspects and simulation results of the magnetic circuit. First results of the Planck constant should be available at the time of the conference.

In the context of the future definition of the mass unit, a promising approach is to link the kilogram to the Planck constant using, for example a watt balance. The Federal Institute of Metrology METAS is pursuing this route and is currently setting up a second version of the experiment. This METAS watt balance Mark II experiment is now assembled and ready for the first experimental tests. The design and the operation are described in this paper, and the first results should be available at the time of the conference.

The METAS watt balance project has been in operation for 10 years. After different improvements and modifications, the present setup allows a reproducibility for a two weeks measurement series of 0.05 × 10-6 W/W. The analysis of several measurement campaigns is underway to produce a value of the Planck's constant h in the near future.

A recent paper (Baumann et al 2009 Metrologia 46 178?86) presents a method to evaluate the free-fall acceleration at a desired point in space, as required for the watt balance experiment. The claimed uncertainty of their absolute gravity measurements is supported by two bilateral comparisons using two absolute gravimeters of the same type. This comment discusses the case where absolute gravity measurements are traceable to a key comparison reference value. Such an approach produces a more complete uncertainty budget and reduces the risk of the results of different watt balance experiments not being compatible.

At the Swiss Federal Office of Metrology and Accreditation (METAS) a quantum primary standard of capacitance based on single electron tunneling devices is under development. In this paper we report on the progress made so far as well as on the current work towards the realization of this standard

At the Swiss Federal Office of Metrology and Accreditation (METAS), the watt balance apparatus has undergone important changes in the magnetic circuit. A new magnet design has been carefully studied, experimentally tested and successfully integrated in the existing set-up. The details of this development as well as new alignment capabilities are described

The Swiss Federal Office of Metrology and Accreditation (METAS) has been continuing to work toward a 100-g watt balance apparatus with an uncertainty of 1 /spl times/10/sup -8/ W/W. Currently the experiment is producing preliminary measurements reproducible at the 1 /spl times/10/sup -6/ W/W level. Our progress, measurements, and plans for the future are presented.

The permanent magnet of the METAS watt balance is one of the key components of the experiment. Its properties and behavior during the different phases of the experiment must be fully characterized. The importance of thermal and magnetic behavior due to weighing current has been extensively studied with the present design.

The Swiss Federal Office of Metrology and Accreditation (METAS) has been continuing its drive towards a 100 g watt balance apparatus with a relative standard uncertainty of 1/spl times/10/sup -8/. The objective of this kind of measurement is, presently, to measure the Planck constant and improve the consistency of the SI. In the future it is hoped that the watt balance approach will help in a redefinition of the kilogram. Currently the experiment is producing preliminary measurements reproducible at the 1 ppm level. Our progress, measurements, and plans for the future are presented.

The European COUNT project exploits two complementary single electron tunneling (SET) devices for use in electrical current metrology: a single electron pump as a current source and a single electron counter as a current meter. Apart from being a quantum current standard, the electron pump could be the basis of a capacitance standard.

A new type of moving-coil Watt balance with a compact design is under construction at the Swiss Federal Office of Metrology (OFMET), Recently, several key components of the system have been characterized. In this paper, a detailed description of the mechanical setup, an assessment of the magnet, the optical system for speed measurement and regulation, and the programmable Josephson voltage standard are reported.

The principle of Coulomb charging effects in single electron tunneling (SET) devices is well understood in terms of the ‘orthodox theory’. However, known deviations arise due to dissipative heating effects, higher-order tunneling or coupling to the electromagnetic environment. Those can be accounted for by more sophisticated theories, which are unfortunately rather unhandy and too general for the analysis of a realistic experiment. Based on extensive DC measurements on metallic SET transistors, we are able to identify all significant deviations (in the weak tunneling limit) and to discuss the relevant theoretical models (i.e. ‘horizon picture’, self-heating) needed for an appropriate description and an intuitive understanding of the experiments.

Control of the tunneling rate of single electrons is possible in systems of small tunnel junctions showing a Coulomb blockade. An external gate potential may be appropriately set to allow the transfer of an exactly given number of charges. With an rf drive at the gate, the de current is consequently determined by the rf frequency. We are currently investigating the feasibility of a new current standard, based on nanometer sized single-electron tunneling devices. A very brief status report is given, and first experimental results on the Coulomb blockade are presented.