Non-Conventional PJVS Exploiting First and Second Steps to Reduce Junctions and Bias Lines

Abstract

Quantum Digital-to-Analog Converters (DACs) based on programmable Josephson array (PJVS) represent the most widely used quantum standard in ac voltage calibrations. The extension of PJVS frequency above the kHz range appears to be arduous, yet some enhancement are still practicable. In this work we demonstrate the possibility to advantageously operate a conventional binary-divided PJVS array with a reduced number of bias lines. This feature is achieved by exploiting both first and second Shapiro steps along with non-conventional DAC codings. Two newly devised bias techniques are described in detail and preliminary experimental tests on waveform synthesis have been carried out and are presented here.

Perovskite-Based Memristor with 50-Fold Switchable Photosensitivity for In-Sensor Computing Neural Network

“…Considering the linearity of the photoresponsivity and the conditions of ion migration, the readout voltage cannot be increased indefinitely. Here we set the maximum read bias to −0.5 V. Because it is easy to realize the multi-level regulation of the bias voltage by using the digital to analog converter (DAC) module, the hybrid modulation method not only increases the control range of the photoresponsivity of the device but also increases the number of states of the photoresponsivity [39][40][41]. With regard to photoresponsivity as the weight of the neural network, the use of hybrid modulation can easily make the accuracy of the weight reach 8 bits, which can further endow the in-sensor computing with more accurate results.…”

Recent advancements and perspectives of INRiM’s time-dependent Josephson voltage standards

“…Subsequently, we deeply investigated the development of programmable standards operating at step orders above the first one, making it possible to synthesize stepwise quantum voltage waveforms with fewer bias lines and fewer Josephson junctions, without losses in terms of performances [20]. In particular, we proposed to simultaneously exploit zero, first and second Shapiro steps to reduce junctions and bias lines by a factor of two.…”

“…In particular, we proposed to simultaneously exploit zero, first and second Shapiro steps to reduce junctions and bias lines by a factor of two. Suitable quantum steps up to the second are easily obtained for the smallest PJVS segments, as shown in [20]. More stringent requirements in terms of rf frequency, power distribution and junctions uniformity of electrical parameters are instead needed for simultaneous operation of largest segments as well.…”

A 10 V PJVS-based DC voltage realization at INRiM

“…The array contains M = 17 sub-arrays of series-connected JJs, each of which can be independently biased to a given Shapiro step. The array is structured with an almost-binary segmentation to limit the number of JJs required to reach the 10 V voltage target, that would be almost doubled with a true-binary segmentation [7]. The implemented array segmentation also enables to accurately verify the quantum operation with nV resolution.…”