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Interface between Quantum and Classical Computers (Master thesis)

Σαββαΐδης, Ιωάννης/ Savvaidis, Ioannis/ Quantum Computing and Quantum Technologies/ Κβαντική Υπολογιστική και Κβαντικές Τεχνολογίες

Quantum computers are increasingly used not as standalone machines but as accelerators within hybrid workflows, in which a classical system prepares a circuit, submits it to a quantum processor, and interprets probabilistic results. This thesis treats the quantum–classical interface as a systems problem rather than a physics one. The orchestration, scheduling, and observability taken for granted in classical cloud-native operations are largely absent at the quantum execution boundary. From a layered analysis of the interface and a survey of existing orchestration and observability work, the thesis derives a set of requirements and answers them with a proof-of-concept, the Quantum Circuit Controller (QCC), a control plane for the quantum–classical interface. It brings cloud-native orchestration and vendor-neutral, standards-based observability to the quantum execution boundary, treating a quantum backend as a managed, observable resource rather than an opaque remote endpoint. Exercised end-to-end on a representative quantum workload across both simulated and real hardware, it satisfies these requirements and makes the computational cost and behaviour of the interface visible. The thesis proposes two standardisation path-ways, a vendor-neutral execution interface and a set of quantum observability conventions. Throughout, the work brings the discipline of site reliability engineering to the quantum–classical space.