Optimizing Classical Hardware for Improved Superconducting Qubit Control

Abstract

Many companies are working towards creating large-scale quantum computers which are expected to help solve important problems in fields ranging from medicine to economics. To achieve effective quantum computers of this scale, it is imperative that we are able to exercise good control over our qubits. Currently, superconducting qubits are one of the most popular platforms for quantum computing. Classical hardware is used to control these qubits, but sometimes the hardware can have deleterious effects on the sensitive quantum information which these qubits store. In other instances, the hardware might require manual re-calibration which cost time and resources. In this thesis, we tackle instances of these problems via two projects. In the first, we implement a radio frequency switch on a qubit drive line to reduce noise from amplifiers. We show that the switch successfully reduces adverse effects of this noise on a fluxonium qubit, evidenced by increased qubit single shot fidelities at (\phi_{ext}=0) and (\phi_{ext}=\pi), and by an increased (T_{1}) at (\phi_{ext}=\pi). In the second project, we write code designed to auto-calibrate the output power of a radio frequency qubit controller. We demonstrate that the calibration code can generate signals, with frequencies between 0-5 GHz, at desired output powers, and that it can do so with average errors below 0.35 dBm.