Feasibility of the Josephson voltage and current standards on a single chip

TL;DR

This paper demonstrates the potential to integrate Josephson voltage and current standards on a single chip, showing quantization at high frequencies but with room for accuracy improvements, advancing quantum metrology.

Contribution

It provides experimental evidence of voltage and current quantization on the same chip up to 10 GHz, paving the way for integrated quantum standards in metrology.

Findings

Voltage quantization up to 0.021 mV at 10 GHz

Current quantization up to 3.23 nA at 10 GHz

Quantization accuracy of 35 ppk for voltage and 100 ppk for current

Abstract

The quantum Josephson voltage standard is well established across the metrology community for many years. It relies on the synchronisation of the flux tunneling in the S/I/S Josepson junctions (JJ) with the microwave radiation (MW). The phenomenon is called the Shapiro steps. Together with the Quantum Hall resistance standard, the voltage standard forms the foundation of electrostatic metrology. The current is then defined as the ratio of the voltage and resistance. Realisation of the quantum current standard, would close the electrostatic metrological triangle of voltage-resistance-current. The current quantisation, the inverse Shapiro steps, was recently shown using the superconducting nanowires and small JJ. The effect is a synchronization of the MW with the Cooper pair tunnelling. This paves the way to combine the JJ voltage and current standards on the same chip and demonstrate feasibility of the multi-standard operation. We show the voltage and current quantization on the same chip up to frequency of 10 GHz, corresponding to the amplitudes 0.021 mV and 3.23 nA respectively. The accuracy of the voltage and current quantisation, however, is relatively low, 35 ppk and 100 ppk respectively. We discuss measures to optimise the JJs, circuit and environment to boost the amplitude and accuracy of the standards.