Developing virtual instruments for control and automation of a quantum processor via specialised FPGA hardware

Abstract

Superconducting quantum bits (qubits) are emerging as a leading platform within the field of Quantum Computing. However, current methods for control and readout of superconducting qubits are limited in how pulse sequences can be defined. One emerging solution for flexible pulse sequence generation is the Field-Programmable Gate Array-based Vivace platform. Vivace allows for control pulses to be defined not as a long sequence of points, but as reusable templates that are output at specific times within the sequence. In addition, these templates can be mixed with arbitrary carrier waves through a digital oscillator. This thesis describes the development of software known as virtual instruments, used to control Vivace. These instruments provide a user interface for assembling complex sequences of waveforms and outputting them via Vivace, as well as reading qubit output. The instruments include features such as parameter sweeps of arbitrary numbers of pulses, interleaved averaging, copying of pulses onto multiple ports and quadrature amplitude demodulation. As the instruments are built on top of the Python-based Labber instrument control platform, they can be linked together and coordinated with all other Labber instruments. We use the instruments to successfully perform several types of qubit characterisation measurements such as Rabi measurements and Ramsey interferometry, among others. In addition, we write a script which automates the sequential execution of several such measurements, allowing for convenient qubit characterisation.