Toward Declarative Platform-Independent Modeling of Hybrid Quantum--Classical Software

Abstract

Quantum hardware platforms are heterogeneous (gate- and analog-based devices, quantum networks, etc.), requiring quantum software to match platform-specific implementations (quantum circuits, adiabatic evolution) and users to hold quantum-mechanics expertise, thus limiting both the user base and program portability across devices. Model-driven engineering addresses those problems by separating platform-independent models from platform-specific realizations, enhancing portability and design of quantum programs. To concretely apply those principles, we present H-hat, a rule system and language family that applies this separation inside the language: classical and quantum code coexist in one program, and quantum is a first-class, lazily evaluated, linear entity under ownership rules and declarative paradigm, with no quantum-physics constructs exposed to the user. A reflective cast mechanism realizes one platform-independent quantum model into many platform-specific ones on concrete backends, connecting quantum program to its classical outcome. We describe H-hat rule system, the quantum data model, and the cast mechanism, illustrated by a quantum teleportation case study, and outline the open challenges toward declarative platform-independent quantum software.