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A single-unit thermal converter for precision ac current measurement is desirable because of its relatively small package and low power dissipation. In this article, high-current multijunction thermal converters (HC-MJTCs) on silicon (Si) substrates fabricated by wet chemical etching have been investigated at input rms currents of up to 2 A. The use of wet chemical etching aids the fabrication of a freestanding nitride–oxide membrane, maintaining the Si heat reservoir under the heater of the HC-MJTC intact. Below 10 mPa, the output voltage from the HC-MJTC and the thermal time-constant increase by approximately six times, implying improved efficiency of the thermal current converter. The absolute value of the ac–dc differences of the device was less than $17~\mu \text{A}$ /A over input current levels of up to 2 A at frequencies above 100 Hz. However, input current level-dependent ac–dc differences were observed at frequencies below 400 Hz even under vacuum. This behavior originated primarily from a change in the electrical resistance of the heater in this Si-based device. Therefore, these low-frequency ac–dc differences can be substantially compensated using the measured ac and dc electrical resistances of the heater.

International audience; Electron flying qubits are envisioned as potential information link within a quantum computer, but also promise -- alike photonic approaches -- a self-standing quantum processing unit. In contrast to its photonic counterpart, electron-quantum-optics implementations are subject to Coulomb interaction, which provide a direct route to entangle the orbital or spin degree of freedom. However, the controlled interaction of flying electrons at the single particle level has not yet been established experimentally. Here we report antibunching of a pair of single electrons that is synchronously shuttled through a circuit of coupled quantum rails by means of a surface acoustic wave. The in-flight partitioning process exhibits a reciprocal gating effect which allows us to ascribe the observed repulsion predominantly to Coulomb interaction. Our single-shot experiment marks an important milestone on the route to realise a controlled-phase gate for in-flight quantum manipulations.

An accurate current can be realized by a series connection of an invariant voltage and resistance with zero interconnection resistance in the framework of Ohm’s law. In practice, however, accurate current realization is limited by the temporal drift and instability of employed resistors, solid-state voltage sources and interconnection wires against environmental fluctuations, such as temperature or atmospheric pressure. Here, we generated a current of 1 μA, determined by the Josephson voltage and quantized Hall resistance array (QHRA). A programmable Josephson voltage standard (PJVS), 1 MΩ QHRA and ultrastable low noise current amplifier (ULCA) are connected in series to generate and measure a current of 1 μA. The expected current is calculated as the ratio of the Josephson voltage to the QHRA plus the output resistance of the PJVS. The relative difference between the current measured by the ULCA and the calculated current is as small as 40 nA A−1 with a combined measurement uncertainty (k = 1) of 0.13 μA A−1.

A set of standard resistors is a key component of resistance calibration. We have been developing a series of compact superstable standard resistors that meet calibration laboratory demands. In this paper, we describe manufacturing and evaluation of ${1}~{\mathrm {k}\Omega }$ standard resistors. All the resistors elements are made with the “stress free bulk metal foil” technology. We found that all standard resistors show extremely small average drift rates, e.g., smaller than ${10~\mathrm {n}\Omega /(\Omega ~\mathrm {year})}$ and small temperature coefficients typically around $35~{{n}\Omega /(\Omega \, {}^\circ \mathrm {C})}$ at 23 °C. Moreover, continuing the evaluation of drift behavior of $ {1}~{\Omega }$ and $ {10}~{\Omega }$ standard resistors is discussed.

A $100\ \Omega$ metal-foil standard resistor was acquired and characterized for pilot study on its transportation behaviour. For the bilateral comparison between NMC and NMIJ, the metal-foil resistor and a wire-wound standard resistor were used as travelling artifacts in a watertight transportation case with environmental monitoring and transported using normal courier services. Measurements were carried out by comparison against QHR standard at NMC and NMIJ. The measurement results shown that the metal-foil resistor has excellent stability and no noticeable difference has been detected compared with the wire-wound standard resistor. The performance of the metal-foil resistor has demonstrated that it is well suitable for use in international resistance comparisons.