Add ActOnCliffordTableauArgs. Support it in _act_on_ for common gates…

… and measurements. (#3063)

#2948 #2423

cirq/__init__.py

@@ -327,6 +327,7 @@
 )
 
 from cirq.sim import (
+    ActOnCliffordTableauArgs,
     ActOnStateVectorArgs,
     StabilizerStateChForm,
     CIRCUIT_LIKE,

cirq/ops/common_gates.py

@@ -84,6 +84,27 @@ def _apply_unitary_(self, args: 'protocols.ApplyUnitaryArgs'
             args.available_buffer *= p
         return args.available_buffer
 
+    def _act_on_(self, args: Any):
+        from cirq.sim import clifford
+
+        if isinstance(args, clifford.ActOnCliffordTableauArgs):
+            if protocols.is_parameterized(self) or self.exponent % 0.5 != 0:
+                return NotImplemented
+            tableau = args.tableau
+            q = args.axes[0]
+            effective_exponent = self._exponent % 2
+            if effective_exponent == 0.5:
+                tableau.xs[:, q] ^= tableau.zs[:, q]
+                tableau.rs[:] ^= (tableau.xs[:, q] & tableau.zs[:, q])
+            elif effective_exponent == 1:
+                tableau.rs[:] ^= tableau.zs[:, q]
+            elif effective_exponent == 1.5:
+                tableau.rs[:] ^= tableau.xs[:, q] & tableau.zs[:, q]
+                tableau.xs[:, q] ^= tableau.zs[:, q]
+            return True
+
+        return NotImplemented
+
     def in_su2(self) -> 'XPowGate':
         """Returns an equal-up-global-phase gate from the group SU2."""
         return XPowGate(exponent=self._exponent, global_shift=-0.5)
@@ -279,6 +300,29 @@ def _apply_unitary_(self, args: 'protocols.ApplyUnitaryArgs'
             args.available_buffer *= p
         return args.available_buffer
 
+    def _act_on_(self, args: Any):
+        from cirq.sim import clifford
+
+        if isinstance(args, clifford.ActOnCliffordTableauArgs):
+            if protocols.is_parameterized(self) or self.exponent % 0.5 != 0:
+                return NotImplemented
+            tableau = args.tableau
+            q = args.axes[0]
+            effective_exponent = self._exponent % 2
+            if effective_exponent == 0.5:
+                tableau.rs[:] ^= (tableau.xs[:, q] & (~tableau.zs[:, q]))
+                (tableau.xs[:, q], tableau.zs[:, q]) = (tableau.zs[:, q].copy(),
+                                                        tableau.xs[:, q].copy())
+            elif effective_exponent == 1:
+                tableau.rs[:] ^= tableau.xs[:, q] ^ tableau.zs[:, q]
+            elif effective_exponent == 1.5:
+                tableau.rs[:] ^= (~(tableau.xs[:, q]) & tableau.zs[:, q])
+                (tableau.xs[:, q], tableau.zs[:, q]) = (tableau.zs[:, q].copy(),
+                                                        tableau.xs[:, q].copy())
+            return True
+
+        return NotImplemented
+
     def in_su2(self) -> 'YPowGate':
         """Returns an equal-up-global-phase gate from the group SU2."""
         return YPowGate(exponent=self._exponent, global_shift=-0.5)
@@ -425,6 +469,27 @@ def _apply_unitary_(self, args: 'protocols.ApplyUnitaryArgs'
             args.target_tensor *= p
         return args.target_tensor
 
+    def _act_on_(self, args: Any):
+        from cirq.sim import clifford
+
+        if isinstance(args, clifford.ActOnCliffordTableauArgs):
+            if protocols.is_parameterized(self) or self.exponent % 0.5 != 0:
+                return NotImplemented
+            tableau = args.tableau
+            q = args.axes[0]
+            effective_exponent = self._exponent % 2
+            if effective_exponent == 0.5:
+                tableau.rs[:] ^= (tableau.xs[:, q] & tableau.zs[:, q])
+                tableau.zs[:, q] ^= tableau.xs[:, q]
+            elif effective_exponent == 1:
+                tableau.rs[:] ^= tableau.xs[:, q]
+            elif effective_exponent == 1.5:
+                tableau.rs[:] ^= tableau.xs[:, q] & (~tableau.zs[:, q])
+                tableau.zs[:, q] ^= tableau.xs[:, q]
+            return True
+
+        return NotImplemented
+
     def _decompose_into_clifford_with_qubits_(self, qubits):
         from cirq.ops.clifford_gate import SingleQubitCliffordGate
         if self.exponent % 2 == 0:
@@ -685,6 +750,24 @@ def _apply_unitary_(self, args: 'protocols.ApplyUnitaryArgs'
         args.target_tensor *= np.sqrt(2) * p
         return args.target_tensor
 
+    def _act_on_(self, args: Any):
+        from cirq.sim import clifford
+
+        if isinstance(args, clifford.ActOnCliffordTableauArgs):
+            if protocols.is_parameterized(self) or self.exponent % 0.5 != 0:
+                return NotImplemented
+            tableau = args.tableau
+            q = args.axes[0]
+            if self._exponent % 1 != 0:
+                return NotImplemented
+            if self._exponent % 2 == 1:
+                (tableau.xs[:, q], tableau.zs[:, q]) = (tableau.zs[:, q].copy(),
+                                                        tableau.xs[:, q].copy())
+                tableau.rs[:] ^= (tableau.xs[:, q] & tableau.zs[:, q])
+            return True
+
+        return NotImplemented
+
     def _decompose_(self, qubits):
         q = qubits[0]
 
@@ -792,6 +875,30 @@ def _apply_unitary_(self, args: 'protocols.ApplyUnitaryArgs'
             args.target_tensor *= p
         return args.target_tensor
 
+    def _act_on_(self, args: Any):
+        from cirq.sim import clifford
+
+        if isinstance(args, clifford.ActOnCliffordTableauArgs):
+            if protocols.is_parameterized(self) or self.exponent % 1 != 0:
+                return NotImplemented
+            tableau = args.tableau
+            q1 = args.axes[0]
+            q2 = args.axes[1]
+            if self._exponent % 2 == 1:
+                (tableau.xs[:, q2], tableau.zs[:, q2]) = \
+                 (tableau.zs[:, q2].copy(), tableau.xs[:, q2].copy())
+                tableau.rs[:] ^= tableau.xs[:,q1] & tableau.zs[:,q2] & \
+                    (tableau.xs[:,q2] ^ tableau.zs[:,q1])
+                tableau.xs[:, q2] ^= tableau.xs[:, q1]
+                tableau.zs[:, q1] ^= tableau.zs[:, q2]
+                (tableau.xs[:, q2],
+                 tableau.zs[:, q2]) = (tableau.zs[:, q2].copy(),
+                                       tableau.xs[:, q2].copy())
+                tableau.rs[:] ^= (tableau.xs[:, q2] & tableau.zs[:, q2])
+            return True
+
+        return NotImplemented
+
     def _pauli_expansion_(self) -> value.LinearDict[str]:
         if protocols.is_parameterized(self):
             return NotImplemented
@@ -858,8 +965,7 @@ def controlled(self,
     def _circuit_diagram_info_(self, args: 'cirq.CircuitDiagramInfoArgs'
                               ) -> 'cirq.CircuitDiagramInfo':
         return protocols.CircuitDiagramInfo(
-                wire_symbols=('@', '@'),
-                exponent=self._diagram_exponent(args))
+            wire_symbols=('@', '@'), exponent=self._diagram_exponent(args))
 
     def _qasm_(self, args: 'cirq.QasmArgs',
                qubits: Tuple['cirq.Qid', ...]) -> Optional[str]:
@@ -973,6 +1079,24 @@ def _apply_unitary_(self, args: 'protocols.ApplyUnitaryArgs'
             args.target_tensor *= p
         return args.target_tensor
 
+    def _act_on_(self, args: Any):
+        from cirq.sim import clifford
+
+        if isinstance(args, clifford.ActOnCliffordTableauArgs):
+            if protocols.is_parameterized(self) or self.exponent % 1 != 0:
+                return NotImplemented
+            tableau = args.tableau
+            q1 = args.axes[0]
+            q2 = args.axes[1]
+            if self._exponent % 2 == 1:
+                tableau.rs[:] ^= (tableau.xs[:, q1] & tableau.zs[:, q2] &
+                                  (~(tableau.xs[:, q2] ^ tableau.zs[:, q1])))
+                tableau.xs[:, q2] ^= tableau.xs[:, q1]
+                tableau.zs[:, q1] ^= tableau.zs[:, q2]
+            return True
+
+        return NotImplemented
+
     def _pauli_expansion_(self) -> value.LinearDict[str]:
         if protocols.is_parameterized(self):
             return NotImplemented