added sample_gates_test.py

Author: NoureldinYosri

cirq-core/cirq/testing/sample_gates.py

@@ -17,6 +17,8 @@
 
 
 class GateThatAllocatesAQubit(ops.Gate):
+    r"""A gate that applies $Z^\theta$ indirectly through a clean ancilla."""
+
     def __init__(self, theta: float) -> None:
         super().__init__()
         self._theta = theta
@@ -35,6 +37,8 @@ def target_unitary(self) -> np.ndarray:
 
 
 class GateThatAllocatesTwoQubits(ops.Gate):
+    r"""A gate that applies $-j Z \otimes Z$ indirectly through two ancillas."""
+
     def _num_qubits_(self):
         return 2
 
@@ -53,16 +57,18 @@ def _decompose_(self, qs):
 
     @classmethod
     def target_unitary(cls) -> np.ndarray:
-        # Unitary = (-j I_2) \otimes Z
+        # Unitary = -j Z \otimes Z
         return np.array([[-1j, 0, 0, 0], [0, 1j, 0, 0], [0, 0, 1j, 0], [0, 0, 0, -1j]])
 
 
 class GateThatDecomposesIntoNGates(ops.Gate):
-    def __init__(self, n: int, sub_gate: ops.Gate, theta: float) -> None:
+    r"""Applies $(Z^\theta)^{\otimes_n}$ on work qubits and `subgate` on $n$ borrowable ancillas."""
+
+    def __init__(self, n: int, subgate: ops.Gate, theta: float) -> None:
         super().__init__()
         self._n = n
-        self._subgate = sub_gate
-        self._name = str(sub_gate)
+        self._subgate = subgate
+        self._name = str(subgate)
         self._theta = theta
 
     def _num_qubits_(self) -> int:

cirq-core/cirq/testing/sample_gates_test.py

@@ -0,0 +1,58 @@
+# Copyright 2023 The Cirq Developers
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import functools
+import pytest
+
+import numpy as np
+from cirq.testing import sample_gates
+from cirq import protocols, ops
+
+
+@pytest.mark.parametrize('theta', np.linspace(0, 2 * np.pi, 20))
+def test_GateThatAllocatesAQubit(theta: float):
+    g = sample_gates.GateThatAllocatesAQubit(theta)
+
+    want = np.array([[1, 0], [0, (-1 + 0j) ** theta]], dtype=np.complex128)
+    # test unitary
+    np.testing.assert_allclose(g.target_unitary(), want)
+
+    # test decomposition
+    np.testing.assert_allclose(protocols.unitary(g), g.target_unitary())
+
+
+def test_GateThatAllocatesTwoQubits():
+    g = sample_gates.GateThatAllocatesTwoQubits()
+
+    Z = np.array([[1, 0], [0, -1]])
+    want = -1j * np.kron(Z, Z)
+    # test unitary
+    np.testing.assert_allclose(g.target_unitary(), want)
+
+    # test decomposition
+    np.testing.assert_allclose(protocols.unitary(g), g.target_unitary())
+
+
+@pytest.mark.parametrize('n', [*range(1, 6)])
+@pytest.mark.parametrize('subgate', [ops.Z, ops.X, ops.Y, ops.T])
+@pytest.mark.parametrize('theta', np.linspace(0, 2 * np.pi, 5))
+def test_GateThatDecomposesIntoNGates(n: int, subgate: ops.Gate, theta: float):
+    g = sample_gates.GateThatDecomposesIntoNGates(n, subgate, theta)
+
+    U = np.array([[1, 0], [0, (-1 + 0j) ** theta]], dtype=np.complex128)
+    want = functools.reduce(np.kron, [U] * n)
+    # test unitary
+    np.testing.assert_allclose(g.target_unitary(), want)
+
+    # test decomposition
+    np.testing.assert_allclose(protocols.unitary(g), g.target_unitary())