Predict and Conquer: Navigating Algorithm Trade-offs with Quantum Design Automation

Abstract

Combining quantum computers with classical compute power has become a standard means for developing algorithms that are eventually supposed to beat any purely classical alternatives. While in-principle advantages for solution quality or runtime are expected for many approaches, substantial challenges remain: Non-functional properties like runtime or solution quality of many approaches are not fully understood, and need to be explored empirically. This makes it unclear which approach is best suited for a given problem. Accurately predicting behaviour of quantum-classical algorithms opens possibilities for software abstraction layers, which can automate decision-making for algorithm selection and parametrisation. While such techniques find frequent use in classical high-performance computing, they are still mostly absent from quantum toolchains. We present a methodology to perform algorithm selection based on desirable non-functional requirements. This simplifies decision-making processes for users. Based on annotations at the source code level, our framework traces key characteristics of quantum-classical algorithms, and uses this information to predict the most suitable approach and its parameters for given computational challenges and their non-functional requirements. As combinatorial optimisation is a very extensively studied aspect of quantum-classical systems, we perform a comprehensive case study based on numerical simulations of algorithmic approaches to implement and validate our ideas. We develop statistical models to quantify the influence of various factors on non-functional properties, and establish predictions for optimal algorithmic choices without manual effort. We argue that our methodology generalises to problems beyond combinatorial optimisation, such as Hamiltonian simulation, and lays a foundation for integrated software layers for quantum design automation.