Entanglement-Optimal Fine-Tuning: Leveraging Structural Concept Coupling for Parameter-Efficient Adaptation

Structural entanglement predicts fine-tuning interference proportional to crosstalk between domains. 8-seed strong-intervention replication shows B3 (code+NL) drives entanglement intensity to zero in all Qwen-32B seeds — a sharp phase transition at steps 2000-3500. Cross-family replication on CodeLlama-7B and DeepSeek-Coder-6.7B confirms the collapse is Qwen-specific. Probe validation with three independent sets (including 132 real-dataset probes) confirms the collapse is genuine geometric destruction. CSR (complement-subspace regularization) preserves structure with 95% CI spanning zero.