A modular and customizable open-source package for quantum voltage standards operation and control

Abstract

This paper presents an open-source package developed in Python that controls and drives a programmable Josephson array to synthesize dc and ac quantum-accurate voltages. Programmable arrays are devices subdivided into independent subsections, each counting a number of series connected Josephson junctions that follows a binary sequence (1, 2, 4, 8, …) to control the output voltage. Our software allows to independently measure the current-voltage characteristics of each subsection by means of a set of arbitrary waveform generators and a nanovoltmeter that measures the voltage across the whole array with high sensitivity. A quantization test tool is also provided to check with sub-microvolt resolution whether the array is operating on its quantum margins. The code is modular and easily expandable with the support of many libraries, allowing prompt reconfiguration for different calibration and testing purposes. It is aimed at being a starting point for cooperation between National Metrology Institutes towards the realization of a shared quantum voltage calibration infrastructure.

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

“…Each AT-1104 module has four independent output channels, thus four modules are needed to drive all the thirteen segments of a conventional 13-bit binary array. To that aim, a specific Python tool that remotely controls each AT-1104 module was developed and customized [29]. As explained in Section IV-A, the operating temperature has to be set to optimize the junctions characteristic voltage V c : at 76.5 GHz, the optimal coupling between the rf excitation and both fundamental (n = 1) and second harmonic (n = 2) Josephson oscillations occurs for V c 240 µV, at midpoint between f rf /K J and 2f rf /K J .…”

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

“…The high complexity of quantum-based devices places software in a fundamental role. We developed at INRiM a Python package for automated measurements with a modular and expandable structure [16] suited to different calibration and testing purposes. Differently from the existing software, as the closed-source software distributed within commercial systems, the open-source approach adopted offers a well-known and tested framework for these needs, based on a collaborative effort and improved by shared information and the updates contributed by the community.…”

Advancements in quantum voltage standards for time-dependent signals

“…The high complexity of quantum based devices, places software in a fundamental role. We developed a Python package for automated measurements with a modular and expandable structure [14] suited to different calibration and testing purposes. The open source approach adopted offers a well known and tested framework for these needs, based on a collaborative effort and improved by shared information and the updates contributed by the community.…”