RSFQ All-Digital Programmable Multi-Tone Generator For Quantum Applications

TL;DR

This paper introduces a novel RSFQ-based digital multi-tone generator designed for scalable quantum control, utilizing complex pulse sequences to produce tunable frequency spectra for quantum device applications.

Contribution

The work presents a new RSFQ device architecture that generates multi-tone signals using a Circular Shift Register and comb filter, enhancing quantum system scalability.

Findings

Pulse train frequency depends on CSR pattern and delay line.

Desired tones can be isolated and amplified through pattern and delay selection.

Proposed architectures enable control and readout of quantum device arrays.

Abstract

One of the most important and topical challenges of quantum circuits is their scalability. Rapid Single Flux Quantum (RSFQ) technology is at the forefront of replacing current standard CMOS-based control architectures for a number of applications, including quantum computing and quantum sensor arrays. By condensing the control and readout to SFQ-based on-chip devices that are directly connected to the quantum systems, it is possible to minimise the total system overhead, improving scalability and integration. In this work, we present a novel RSFQ device that generates multi tone digital signals, based on complex pulse train sequences using a Circular Shift Register (CSR) and a comb filter stage. We show that the frequency spectrum of the pulse trains is dependent on a preloaded pattern on the CSR, as well as on the delay line of the comb filter stage. By carefully selecting both the pattern and delay, the desired tones can be isolated and amplified as required. Finally, we propose architectures where this device can be implemented to control and readout arrays of quantum devices, such as qubits and single photon detectors.