Design and Implementation of a Local Controller for Diamond Quantum Computers

Abstract

As classical computing paradigms approach their physical limits, quantum computing has emerged as a promising solution capable of solving certain complex problems with substantial speedup. However, before quantum computers can be deployed in real-world situations, they must be able to scale up to thousands of qubits with high fidelity while maintaining the ability to accurately and precisely control each qubit. This requires a part of the digital control logic placed close to each qubit that orchestrates the control signals sent to each qubit -- the local controller. This thesis focuses on the design and implementation of this local controller for operations on diamond qubits, building on top of an existing control architecture, from specifying the design requirements to actual hardware implementation and verification.

Multiple contributions are made in this thesis towards realizing a fully functional local controller design. The required functionalities for full support of all quantum operations are identified. Based on these functionalities, the designs of the new components and microinstructions are proposed. These designs are implemented as microcode and circuit architectures. In this process, a control sequence and relevant architecture for entanglement generation between color centers are proposed and implemented. An improved communication scheme with the network of local controllers has also been implemented to meet functional requirements and facilitate performance improvements. The new implementations are verified and prototyped on an FPGA performing actual quantum operations, demonstrating that the local controller is capable of performing all types of quantum operations with sufficient accuracy and precision, integrating seamlessly with peripheral components in the quantum control layer.

The work of this thesis represents a major step forward in the microarchitectural stack of a diamond quantum computer, paving the way toward the realization of large-scale quantum computing capable of addressing practical, real-world problems.