Qunicorn: A Middleware for the Unified Execution Across Heterogeneous Quantum Cloud Offerings

Quantum computers are available via a variety of different quantum cloud offerings. These offerings are heterogeneous and differ in features, such as pricing models or types of access to quantum computers. Furthermore, quantum circuits can be implemented using different quantum programming languages, which are typically only supported by a small subset of quantum cloud offerings. As a consequence, using a specific quantum programming language for implementing the application at hand can limit the set of compatible quantum cloud offerings and cause a vendor lock-in. Therefore, selecting a suitable quantum cloud offering and a corresponding quantum programming language requires knowledge about their features. In this paper, we (i) analyze the available quantum cloud offerings and extract their features. Moreover, we (ii) introduce the architecture for a unification middleware that facilitates accessing quantum computers available via different quantum cloud offerings by automatically translating between various quantum circuit and result formats. To showcase the practical feasibility of our approach, we (iii) present a prototypical implementation and validate it for three exemplary application scenarios.