Connecting Quantum Software Stacks - MQSS and QCI Connect

Kurzfassung

Quantum computing systems are increasingly accessed through software stacks that hide hardware-specific details behind higher-level abstractions. This is necessary because current quantum resources differ in their physical realisation, supported program formats, execution parameters, calibration data, status models, and result representations. At the same time, independent software stack initiatives create an interoperability challenge: even systems with similar goals may not communicate directly if their APIs encode different assumptions. This thesis studies this problem for the Munich Quantum Software Stack (MQSS), whose backend abstraction is the Quantum Device Management Interface (QDMI), and QCI Connect, a modular full-stack quantum computing platform developed within the DLR Quantum Computing Initiative. The goal is to connect these systems bidirectionally while preserving their architectural abstractions. In one direction, MQSS resources are exposed as QCI Connect QPUs via a dedicated QPU connector. In the other direction, QCI Connect is exposed as a QDMI-compatible device that translates QDMI session, query, job, status, cancellation, and result calls into QCI Connect API requests. The thesis compares the relevant API concepts and implements mappings for resource discovery, job submission, status handling, cancellation, and result retrieval. The implementation shows that bidirectional communication is feasible through existing extension points in both stacks. It also reveals semantic mismatches, including incomplete metadata equivalence, differences in status granularity, assumptions about circuit formats, and result fields requiring custom handling. These findings show that interoperability between quantum software stacks is possible, but long-term portability requires clearer standardisation of capabilities, execution parameters, status models, and result schemas.