Control-Plane Openness in Near-Term Quantum Computing: A Survey of Vendor Stacks and Field Implications

Public access to pulse-level and control-electronics interfaces in commercial quantum computing has bifurcated. The largest superconducting cloud platforms have closed access at this layer, with IBM removing pulse-level control from all production QPUs in February 2025; mid-tier superconducting vendors and the more open neutral-atom platforms have moved in the opposite direction. We survey thirteen commercial vendors across superconducting, trapped-ion, neutral-atom, and photonic modalities, grading each on six axes of openness at what we call the control plane: the layer between gate-level circuit specification and physical control electronics. The catalog ships as a separate machine-readable artifact under CC-BY-4.0 (DOI: https://doi.org/10.5281/zenodo.20163276). The bifurcation is documented row by row, with implications for reproducibility, hardware-aware research, and cross-vendor benchmarking. We do not propose an architecture or a reference implementation; we describe what the field has lost as the access landscape has shifted, and what minimally open access at this layer would have to look like.