Make all non-analytical gate decompositions respect global phase (#5420)

Fixes #4275

Author: tanujkhattar

cirq-core/cirq/ops/common_gates.py

@@ -862,11 +862,11 @@ def _decompose_(self, qubits):
 
         if self._exponent == 1:
             yield cirq.Y(q) ** 0.5
-            yield cirq.XPowGate(global_shift=-0.25).on(q)
+            yield cirq.XPowGate(global_shift=-0.25 + self.global_shift).on(q)
             return
 
         yield YPowGate(exponent=0.25).on(q)
-        yield XPowGate(exponent=self._exponent).on(q)
+        yield XPowGate(exponent=self._exponent, global_shift=self.global_shift).on(q)
         yield YPowGate(exponent=-0.25).on(q)
 
     def _circuit_diagram_info_(
@@ -1134,7 +1134,7 @@ def _decompose_into_clifford_with_qubits_(self, qubits):
     def _decompose_(self, qubits):
         c, t = qubits
         yield YPowGate(exponent=-0.5).on(t)
-        yield CZ(c, t) ** self._exponent
+        yield cirq.CZPowGate(exponent=self._exponent, global_shift=self.global_shift).on(c, t)
         yield YPowGate(exponent=0.5).on(t)
 
     def _eigen_components(self) -> List[Tuple[float, np.ndarray]]:

cirq-core/cirq/ops/common_gates_test.py

@@ -33,9 +33,7 @@ def test_phase_insensitive_eigen_gates_consistent_protocols(eigen_gate_type):
 
 @pytest.mark.parametrize('eigen_gate_type', [cirq.CNotPowGate, cirq.HPowGate])
 def test_phase_sensitive_eigen_gates_consistent_protocols(eigen_gate_type):
-    cirq.testing.assert_eigengate_implements_consistent_protocols(
-        eigen_gate_type, ignoring_global_phase=True
-    )
+    cirq.testing.assert_eigengate_implements_consistent_protocols(eigen_gate_type)
 
 
 def test_cz_init():

cirq-core/cirq/ops/phased_iswap_gate_test.py

@@ -141,8 +141,7 @@ def test_phased_iswap_has_consistent_protocols(phase_exponent, exponent, global_
     cirq.testing.assert_implements_consistent_protocols(
         cirq.PhasedISwapPowGate(
             phase_exponent=phase_exponent, exponent=exponent, global_shift=global_shift
-        ),
-        ignoring_global_phase=False,
+        )
     )
 
 
@@ -206,6 +205,4 @@ def test_givens_rotation_equivalent_circuit():
 
 @pytest.mark.parametrize('angle_rads', (-np.pi / 5, 0.4, 2, np.pi))
 def test_givens_rotation_has_consistent_protocols(angle_rads):
-    cirq.testing.assert_implements_consistent_protocols(
-        cirq.givens(angle_rads), ignoring_global_phase=False
-    )
+    cirq.testing.assert_implements_consistent_protocols(cirq.givens(angle_rads))

cirq-core/cirq/ops/swap_gates_test.py

@@ -207,6 +207,4 @@ def test_riswap_hamiltonian(angle_rads):
 
 @pytest.mark.parametrize('angle_rads', (-np.pi / 5, 0.4, 2, np.pi))
 def test_riswap_has_consistent_protocols(angle_rads):
-    cirq.testing.assert_implements_consistent_protocols(
-        cirq.riswap(angle_rads), ignoring_global_phase=False
-    )
+    cirq.testing.assert_implements_consistent_protocols(cirq.riswap(angle_rads))

cirq-core/cirq/ops/three_qubit_gates.py

@@ -42,6 +42,7 @@
     raw_types,
     swap_gates,
     raw_types,
+    global_phase_op,
 )
 
 if TYPE_CHECKING:
@@ -117,8 +118,13 @@ def _decompose_(self, qubits):
 
         p = common_gates.T**self._exponent
         sweep_abc = [common_gates.CNOT(a, b), common_gates.CNOT(b, c)]
-
-        return [
+        global_phase = 1j ** (2 * self.global_shift * self._exponent)
+        global_phase_operation = (
+            [global_phase_op.global_phase_operation(global_phase)]
+            if protocols.is_parameterized(global_phase) or abs(global_phase - 1.0) > 0
+            else []
+        )
+        return global_phase_operation + [
             p(a),
             p(b),
             p(c),
@@ -337,8 +343,13 @@ def _decompose_(self, qubits):
         ]
         phase_solutions = phase_matrix_inverse.dot(shifted_angles_tail)
         p_gates = [pauli_gates.Z ** (solution / np.pi) for solution in phase_solutions]
-
-        return [
+        global_phase = 1j ** (2 * self._diag_angles_radians[0] / np.pi)
+        global_phase_operation = (
+            [global_phase_op.global_phase_operation(global_phase)]
+            if protocols.is_parameterized(global_phase) or abs(global_phase - 1.0) > 0
+            else []
+        )
+        return global_phase_operation + [
             p_gates[0](a),
             p_gates[1](b),
             p_gates[2](c),
@@ -460,7 +471,7 @@ def _apply_unitary_(self, args: 'protocols.ApplyUnitaryArgs') -> np.ndarray:
     def _decompose_(self, qubits):
         c1, c2, t = qubits
         yield common_gates.H(t)
-        yield CCZ(c1, c2, t) ** self._exponent
+        yield CCZPowGate(exponent=self._exponent, global_shift=self.global_shift).on(c1, c2, t)
         yield common_gates.H(t)
 
     def _circuit_diagram_info_(

cirq-core/cirq/ops/three_qubit_gates_test.py

@@ -22,25 +22,21 @@
 
 @pytest.mark.parametrize('eigen_gate_type', [cirq.CCXPowGate, cirq.CCZPowGate])
 def test_eigen_gates_consistent_protocols(eigen_gate_type):
-    cirq.testing.assert_eigengate_implements_consistent_protocols(
-        eigen_gate_type, ignoring_global_phase=True
-    )
+    cirq.testing.assert_eigengate_implements_consistent_protocols(eigen_gate_type)
 
 
 @pytest.mark.parametrize(
-    'gate,ignoring_global_phase',
+    'gate',
     (
-        (cirq.CSWAP, False),
-        (cirq.ThreeQubitDiagonalGate([2, 3, 5, 7, 11, 13, 17, 19]), True),
-        (cirq.ThreeQubitDiagonalGate([0, 0, 0, 0, 0, 0, 0, 0]), True),
-        (cirq.CCX, False),
-        (cirq.CCZ, False),
+        (cirq.CSWAP),
+        (cirq.ThreeQubitDiagonalGate([2, 3, 5, 7, 11, 13, 17, 19])),
+        (cirq.ThreeQubitDiagonalGate([0, 0, 0, 0, 0, 0, 0, 0])),
+        (cirq.CCX),
+        (cirq.CCZ),
     ),
 )
-def test_consistent_protocols(gate, ignoring_global_phase):
-    cirq.testing.assert_implements_consistent_protocols(
-        gate, ignoring_global_phase=ignoring_global_phase
-    )
+def test_consistent_protocols(gate):
+    cirq.testing.assert_implements_consistent_protocols(gate)
 
 
 def test_init():