Experiences in Quantum Software Engineering

The field of Quantum Computing (QC) is increasingly becoming applicable for a wide range of computationally intensive problems. Especially Variational Quantum Algorithms (VQA) are promising as they allow dealing with the practical challenges of current quantum devices (also referred to as Noisy Intermediate-Scale Quantum devices). However, developing VQA-based solutions is not a straightforward process but involves several development phases, each with different design decisions and implications. In this paper, we share experiences made in developing VQA-based solutions for two different industrial case studies. Based on the solutions, we extracted five generic development phases quantum engineers must take into consideration when engineering quantum solutions. We have embedded the phases in a model (i.e. a phase model) to show their natural order and to illustrate the phases that require more development iterations. The main objective of this paper is not only to share and discuss our findings and experiences but also to provide the phase model as a starting point or guideline to structure the development process.