Add files via upload

Author: JavierMartinAlonso1980

test/test_injection_qiskit.py

@@ -0,0 +1,84 @@
+# test/test_injection_qiskit.py
+"""
+Qiskit 2-qubit injection test suite.
+Verifies that log-negativity and Bell fidelity correctly distinguish
+entangled states from product-state noise.
+
+Skipped automatically if qiskit / qiskit-aer are not installed.
+"""
+
+import pytest
+
+try:
+    from qiskit import QuantumCircuit  # noqa: F401
+    QISKIT_AVAILABLE = True
+except ImportError:
+    QISKIT_AVAILABLE = False
+
+skip_if_no_qiskit = pytest.mark.skipif(
+    not QISKIT_AVAILABLE,
+    reason="qiskit / qiskit-aer not installed"
+)
+
+
+@skip_if_no_qiskit
+def test_bell_state_log_negativity():
+    """Bell state |Φ+⟩ must have E_N ≈ 1.0 (maximum for 2 qubits)."""
+    from src.ibm_validation.injection_tests import (
+        make_bell_circuit, compute_log_negativity
+    )
+    EN = compute_log_negativity(make_bell_circuit())
+    assert EN > 0.95, f"Bell state E_N should be ≈1.0, got {EN:.4f}"
+
+
+@skip_if_no_qiskit
+def test_product_noise_log_negativity():
+    """Product (noise) states must have E_N ≈ 0 regardless of angles."""
+    from src.ibm_validation.injection_tests import (
+        make_noise_circuit, compute_log_negativity
+    )
+    for seed in [0, 7, 42, 99, 123]:
+        qc = make_noise_circuit(seed=seed)
+        EN = compute_log_negativity(qc)
+        assert EN < 1e-9, f"Seed {seed}: noise E_N should be 0, got {EN:.6f}"
+
+
+@skip_if_no_qiskit
+def test_bell_fidelity_is_one():
+    """Bell circuit fidelity with ideal |Φ+⟩ should be exactly 1."""
+    from src.ibm_validation.injection_tests import (
+        make_bell_circuit, compute_bell_fidelity
+    )
+    fidelity = compute_bell_fidelity(make_bell_circuit())
+    assert abs(fidelity - 1.0) < 1e-9, f"Bell fidelity should be 1.0, got {fidelity}"
+
+
+@skip_if_no_qiskit
+def test_injection_signal_clearly_above_noise():
+    """
+    Core injection test: E_N(signal) >> E_N(noise).
+    This mirrors the BasQ vorticity-vs-EM-noise validation pattern.
+    """
+    from src.ibm_validation.injection_tests import (
+        make_bell_circuit, make_noise_circuit, compute_log_negativity
+    )
+    EN_signal = compute_log_negativity(make_bell_circuit())
+    EN_noise = compute_log_negativity(make_noise_circuit(seed=42))
+
+    assert EN_signal > EN_noise + 0.8, (
+        f"Signal and noise not clearly separated: "
+        f"E_N(signal)={EN_signal:.4f}, E_N(noise)={EN_noise:.4f}"
+    )
+
+
+@skip_if_no_qiskit
+def test_full_injection_run_passes():
+    """End-to-end injection test: run_injection_test() must pass."""
+    from src.ibm_validation.injection_tests import run_injection_test
+    results = run_injection_test(shots=2000, noise_seed=42)
+    assert results["passed"], (
+        f"Injection test failed.\n"
+        f"  Signal E_N = {results['signal']['log_negativity']:.4f}\n"
+        f"  Noise  E_N = {results['noise']['log_negativity']:.4f}\n"
+        f"  Status: {results['status']}"
+    )