Fix getting probs from noise channel

Author: david-pl

src/bloqade/noise/fidelity.py

@@ -18,10 +18,14 @@ def single_qubit_gate(
         frame: interp.Frame[EmptyLattice],
         stmt: PauliChannel,
     ):
-        ps, ps_ctrl = stmt.probabilities
-        p = sum(ps)
+        probs = stmt.probabilities
+        try:
+            ps, ps_ctrl = probs
+        except ValueError:
+            (ps,) = probs
+            ps_ctrl = ()
 
-        # NOTE: will be 0 if no ctrls
+        p = sum(ps)
         p_ctrl = sum(ps_ctrl)
 
         # NOTE: fidelity is just the inverse probability of any noise to occur

test/analysis/fidelity/test_fidelity.py

@@ -32,7 +32,11 @@ def main():
 p_loss = 0.01
 
 noise_params = native.GateNoiseParams(
-    global_loss_prob=p_loss, global_px=px, global_py=py, global_pz=pz
+    global_loss_prob=p_loss,
+    global_px=px,
+    global_py=py,
+    global_pz=pz,
+    local_px=0.002,
 )
 
 model = NoiseTestModel()
@@ -46,5 +50,5 @@ def main():
 fid_analysis = FidelityAnalysis(main.dialects)
 fid_analysis.run_analysis(main, no_raise=False)
 
-print(fid_analysis.global_fidelity)
-print(fid_analysis.current_fidelity)
+p_noise = noise_params.local_px + noise_params.local_py + noise_params.local_pz
+assert fid_analysis.global_fidelity == fid_analysis.current_fidelity == (1 - p_noise)