Advances in the Singlet-Triplet Qubit

Abstract

My work on singlet-triplet spin qubits has bridged between the eras of two different semiconductors, gallium arsenide (GaAs) and silicon germanium (SiGe), that have been used in the Yacoby Lab. I have chosen to report my work in chronological order as it fits best with developments in the field but this leaves it with a structure inverted to most experimental physics theses with the main scientific achievements front loaded and the engineering stages at the end. The first chapter will provide background on spin qubits in semiconductors and will focus on major developments in singlet-triplet qubits that supported and motivated my own work. The second chapter discusses an advancement in two qubit coupling based on using large magnetic field gradients to mitigate charge noise. The third chapter is technical details about a new readout mechanism that allowed for the measurements presented in the second chapter. The fourth chapter discusses the transition from GaAs to SiGe and highlights the main difference between these two materials. The fifth chapter details the Crassula Quantum Dot Simulator that was written to aid in designing devices in SiGe. The sixth chapter discusses the progress made towards qubits in SiGe. The seventh chapter discusses overcoming the difficulties of RF reflectometry that are introduced by SiGe. The thesis concludes with experiment ideas that I was not able to complete before graduation but that I wish to note down so that some later generation of students may try them.