Proposal for a multi-technology, template-based quantum circuits compilation toolchain

The promising branch of quantum computing has made some significant advances in the last decade. With quantum hardware becoming larger in scale and more reliable, quantum circuits are growing in size and becoming more complex in their implementations. In order to face the challenge of achieving optimality for these circuits, the state-of-the-art in quantum computing has employed automated design tools for improving and mapping quantum circuits, each one characterized by a specific optimization strategy. In this thesis, the use of a template-based approach for quantum circuits optimization purposes is explored, and the proposal of a modular compilation toolchain – which supports multiple trending quantum implementation technologies - is presented. The Toolchain, which is inspired by the current state-of-the-art design workflow, is entirely developed in Python and designed to optimize quantum circuits described in the OpenQASM intermediate description language. The Toolchain forsakes complex algorithm-based optimizations in favor of the exploitation of circuit identities at computer architecture-level and adapts an initially technology-agnostic quantum circuit to a specific target technology. The currently supported technologies are NMR, Trapped Ions and Superconducting qubits. The Toolchain tackles the tasks of implementing Logic Synthesis and a part of Layout Synthesis in the compilation process and is structured with multiple steps and modular libraries to allow both specific and general purpose optimizations and to realize an easily expandable software structure. The software development of the Toolchain was accompanied by a benchmarking procedure, where it was tested on a subset of complex quantum circuits and the outputs were compared to the ones of IBM’s Qiskit and Cambridge Quantum Computing’s T-KET compilers. Even though the Toolchain can still be expanded further, the results obtained are encouraging and prove that the Toolchain can be competitive in quantum circuits’ optimization, especially when dealing with single-qubit gates.