add random gate for stabilizer circuit

Author: refraction-ray

tensorcircuit/stabilizercircuit.py

@@ -66,7 +66,7 @@ def apply_general_gate(
             "gate": gate,
             "index": index,
             "name": name,
-            "split": False,
+            "split": None,
             "mpo": False,
         }
         ir_dict = kws["ir_dict"]
@@ -89,6 +89,22 @@ def apply_general_gate(
 
     apply = apply_general_gate
 
+    def random_gate(self, *index: int, recorded: bool = False) -> None:
+        """
+        Apply a random Clifford gate to the circuit.
+        This operation will not record in qir
+
+        :param index: Qubit indices to apply the gate to
+        :type index: int
+        :param recorded: Whether the gate is recorded in ``stim.Circuit``, defaults to False
+        :type recorded: bool, optional
+        """
+        m = len(index)
+        t = stim.Tableau.random(m)
+        self.current_sim.do_tableau(t, index)
+        if recorded:
+            self._stim_circuit += t.to_circuit()
+
     def measure(self, *index: int, with_prob: bool = False) -> Tensor:
         """
         Measure qubits in Z basis.

tests/test_stabilizer.py

@@ -134,3 +134,24 @@ def test_to_openqasm():
 
     c1 = tc.StabilizerCircuit.from_openqasm(qasm)
     print(c1.draw())
+
+
+def test_ee():
+    c = tc.Circuit(8)
+    for i in range(3):
+        c.h(i)
+        c.cx(i, i + 4)
+        c.sd(i + 2)
+    ee0 = tc.quantum.entanglement_entropy(c.state(), list(range(4)))
+    c1 = tc.StabilizerCircuit.from_openqasm(c.to_openqasm())
+    ee1 = c1.entanglement_entropy(list(range(4)))
+    np.testing.assert_allclose(ee0, ee1, atol=1e-6)
+
+
+def test_random_gates():
+    c = tc.StabilizerCircuit(4)
+    c.random_gate(0, 1, recorded=True)
+    c.random_gate(2, 3)
+    c.random_gate(1, 2)
+    print(c.entanglement_entropy(list(range(2))))
+    print(len(c.current_circuit()))