Stronger test: W = R1 + R2 + R3 − C1 − C2 − C3. Classical bound W ≤ 4; ideal quantum W = 6. State-optimized 2-qubit preparation, 18 circuits, context-shift diagnostics.
40 restarts × 35 iters, 4096 shots. Best theta found: W ≈ 1.02. R1 and C3 active; R2, R3, C1, C2 near zero.
| Metric | Value |
|---|---|
| Witness W | 0.76 |
| Classical bound | 4 |
| Quantum target | 6 |
| Status | Below noncontextual bound (no contextuality claim) |
| Job ID | d70511s69uic73cjuli0 |
R1 ≈ 0.38, R2 ≈ 0, R3 ≈ 0; C1 ≈ 0, C2 ≈ 0, C3 ≈ −0.38. Shallow 4-parameter ansatz activates mainly R1 and C3; full witness W > 4 would require deeper state preparation or different witness formulation.
Interpretation. The full witness upgrades from “col3 only” to a single score with clear classical/quantum bounds. Current results show the method runs correctly on Fez but W remains far below the contextuality threshold. Next steps: deeper ansatz, 2-qubit W bound check, QPC reducer integration.
Optimize on simulator: python3 qpc_contextuality_witness.py --mode sim-opt --restarts 40 -o best.json
Run on Fez: python3 qpc_contextuality_witness.py --mode ibm --theta-from-file best.json --backend ibm_fez -o fez_results.json
Full pipeline: python3 qpc_contextuality_witness.py --mode full --backend ibm_fez -o fez_results.json