Comparison between Josephson arbitrary waveform synthesizers using a cross-correlation technique

This paper presents an on-site comparison between two dry-type cryocooled Josephson arbitrary waveform synthesizers (JAWS) equipped with chips manufactured by the National Institute of Standards and Technology (NIST) and the National Institute of Metrology (NIM). When a custom dual-channel analog-to-digital converter (ADC) serves as the digitizer and a frequency domain cross-correlation technique is applied, the agreement between the two JAWS is better than 5.8 parts in 1 0 8 at 20 mV root-mean-square (RMS) amplitude in the frequency range from 0.48 kHz to 5 kHz, with an associated uncertainty better than 16 parts in 1 0 8 ( k =2). Moreover, we propose a general approach for predicting the frequency response of JAWS, which involves modeling the transmission network with multisegment lossy transmission cables having distributed parameters, visually presenting the prediction uncertainty through Sobol sequences-based simulations, and conducting a sensitivity analysis by estimating Sobol indices. The excellent agreement observed between the two JAWS, which are equipped with different types of chips, cryostats, and cryocoolers, not only highlights the superiority of quantum voltage standards but also demonstrates the universality of different transportable dry-cryocooled JAWS.