Add CZ to combined FSim gate set (#2875)

* Add CZ to combined FSim gate set
quantumlib · Mar 30, 2020 · 4521a9b · 4521a9b
1 parent 3659c7f
commit 4521a9b
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diff --git a/cirq/google/common_serializers.py b/cirq/google/common_serializers.py
@@ -456,6 +456,10 @@ def _can_serialize_limited_fsim(theta: float, phi: float):
     if ((_near_mod_2pi(theta, np.pi / 2) or isinstance(theta, sympy.Symbol)) and
         (_near_mod_2pi(phi, np.pi / 6)) or isinstance(phi, sympy.Symbol)):
         return True
+    # CZ
+    if ((_near_mod_2pi(theta, 0) or isinstance(theta, sympy.Symbol)) and
+        (_near_mod_2pi(phi, np.pi)) or isinstance(phi, sympy.Symbol)):
+        return True
     return False
 
 
@@ -507,8 +511,22 @@ def _can_serialize_limited_iswap(exponent: float):
         ],
         can_serialize_predicate=(lambda op: _can_serialize_limited_iswap(
             cast(ops.ISwapPowGate, op.gate).exponent))),
+    op_serializer.GateOpSerializer(
+        gate_type=ops.CZPowGate,
+        serialized_gate_id='fsim',
+        args=[
+            op_serializer.SerializingArg(serialized_name='theta',
+                                         serialized_type=float,
+                                         op_getter=lambda e: 0),
+            op_serializer.SerializingArg(serialized_name='phi',
+                                         serialized_type=float,
+                                         op_getter=lambda e: np.pi)
+        ],
+        can_serialize_predicate=lambda op: _near_mod_2(
+            cast(ops.CZPowGate, op.gate).exponent, 1.0))
 ]
 
+
 LIMITED_FSIM_DESERIALIZER = op_deserializer.GateOpDeserializer(
     serialized_gate_id='fsim',
     gate_constructor=ops.FSimGate,

diff --git a/cirq/google/common_serializers_test.py b/cirq/google/common_serializers_test.py
@@ -659,7 +659,10 @@ def test_wait_gate():
     (cirq.ISWAP**0.5, -np.pi / 4, 0),
     (cirq.ISWAP**-0.5, np.pi / 4, 0),
     (cirq.ISWAP**0.0, 0, 0),
+    (cirq.CZ, 0, np.pi),
+    (cirq.CZ**-1.0, 0, np.pi),
     (cirq.FSimGate(theta=0, phi=0), 0, 0),
+    (cirq.FSimGate(theta=0, phi=np.pi), 0, np.pi),
     (cirq.FSimGate(theta=np.pi / 4, phi=0), np.pi / 4, 0),
     (cirq.FSimGate(theta=7 * np.pi / 4, phi=0), 7 * np.pi / 4, 0),
     (cirq.FSimGate(theta=-np.pi / 4, phi=0), -np.pi / 4, 0),