C2|Q>: A Robust Framework for Bridging Classical and Quantum Software Development

Quantum Software Engineering (QSE) is emerging as a critical discipline to make quantum computing accessible to a broader developer community; however, most quantum development environments still require developers to engage with low-level details across the software stack - including problem encoding, circuit construction, algorithm configuration, hardware selection, and result interpretation - making them difficult for classical software engineers to use. To bridge this gap, we present C2|Q>: a hardware-agnostic quantum software development framework that translates classical specifications (code) into quantum-executable programs while preserving methodological rigor. The framework applies modular software engineering principles by classifying the workflow into three core modules: an encoder that classifies problems, produces Quantum-Compatible Formats (QCFs), and constructs quantum circuits, a deployment module that generates circuits and recommends hardware based on fidelity, runtime, and cost, and a decoder that interprets quantum outputs into classical solutions. In evaluation, the encoder module achieved a 93.8% completion rate, the hardware recommendation module consistently selected the appropriate quantum devices for workloads scaling up to 56 qubits, and the full C2|Q>: workflow successfully processed classical specifications (434 Python snippets and 100 JSON inputs) with completion rates of 93.8% and 100%, respectively. For case study problems executed on publicly available NISQ hardware, C2|Q>: reduced the required implementation effort by nearly 40X compared to manual implementations using low-level quantum software development kits (SDKs), with empirical runs limited to small- and medium-sized instances consistent with current NISQ capabilities. The open-source implementation of C2|Q>: is available at https://github.com/C2-Q/C2Q