  Quantum computing promises potential for science and industry by solving
certain computationally complex problems faster than classical computers.
Quantum computing systems evolved from monolithic systems towards modular
architectures comprising multiple quantum processing units (QPUs) coupled to
classical computing nodes (HPC). With the increasing scale, middleware systems
that facilitate the efficient coupling of quantum-classical computing are
becoming critical. Through an in-depth analysis of quantum applications,
integration patterns and systems, we identified a gap in understanding
Quantum-HPC middleware systems. We present a conceptual middleware to
facilitate reasoning about quantum-classical integration and serve as the basis
for a future middleware system. An essential contribution of this paper lies in
leveraging well-established high-performance computing abstractions for
managing workloads, tasks, and resources to integrate quantum computing into
HPC systems seamlessly.
