Measure using StabilizerStateChForm

cirq/sim/clifford/clifford_simulator.py

@@ -370,7 +370,7 @@ def perform_measurement(
             state = self.copy()
 
         for qubit in qubits:
-            result = state.tableau._measure(self.qubit_map[qubit], prng)
+            result = state.ch_form._measure(self.qubit_map[qubit], prng)
             state.ch_form.project_Z(self.qubit_map[qubit], result)
             results.append(result)
 

cirq/sim/clifford/stabilizer_state_ch_form.py

@@ -243,6 +243,19 @@ def to_state_vector(self) -> np.ndarray:
 
         return arr
 
+    def _measure(self, q, prng: np.random.RandomState) -> int:
+        """Measures the q'th qubit.
+
+        Reference: Section 4.1 "Simulating measurements"
+
+        Returns: Computational basis measurement as 0 or 1.
+        """
+        w = self.s.copy()
+        for i, v_i in enumerate(self.v):
+            if v_i == 1:
+                w[i] = bool(prng.randint(2))
+        return sum(w & self.G[q, :]) % 2
+
     def project_Z(self, q, z):
         """Applies a Z projector on the q'th qubit.