Engineering a Control System for a Logical Qubit-Scale Trapped Ion Quantum Computer

Abstract

Quantum computing is a promising field for continuing to develop new computing capabilities, both in its own right and for continued gains as Moore's Law growth ends.Trapped ion quantum computing is a leading technology in the field of quantum computing, as it combines the important characteristics of high fidelity operations, individual addressing, and long coherence times. However, quantum computers are still in their infancy; the first quantum computers to have more than a handful of quantum bits (qubits) are less than a decade old. As research groups push the boundaries of the number of qubits in a system, they are consistently running into engineering obstacles preventing them from achieving their goals. There is effectively a knowledge gap between the physicists who have the capability to push the field of quantum computing forward, and the engineers who can design the large-scale & reliable systems that enable pushing those envelopes. This thesis is an attempt to bridge that gap by framing trapped ion quantum computing in a manner accessible to engineers, as well as improving on the state-of-the-art in quantum computer digital and RF control systems.

We also consider some of the practical and theoretical engineering challenges that arise when developing a leading-edge trapped ion quantum computer capable of demonstrating error-corrected logical qubits, using trapped Ytterbium-171 qubits.There are many fundamental quantum operations that quantum information theory assumes, yet which are quite complicated to implement in reality. First, we address the time cost of rearranging a chain of ions after a scrambling collision with background gases. Then we consider a gate waveform generator that reduces programming time while supporting conditional quantum gates. Next, we discuss the development of a digital control system custom-designed for quantum computing and quantum networking applications. Finally, we demonstrate experimental results of the waveform generator executing novel gate schemes on a chain of trapped ions. These building blocks together will unlock new capabilities in the field of trapped ion quantum computers.