Deprecate cirq.SingleQubitGate (quantumlib#5272)

Fixes quantumlib#4790

cirq/circuits/circuit_test.py

@@ -1884,15 +1884,15 @@ def test_qid_shape_qubit(circuit_cls):
 
 @pytest.mark.parametrize('circuit_cls', [cirq.Circuit, cirq.FrozenCircuit])
 def test_qid_shape_qudit(circuit_cls):
-    class PlusOneMod3Gate(cirq.SingleQubitGate):
+    class PlusOneMod3Gate(cirq.testing.SingleQubitGate):
         def _qid_shape_(self):
             return (3,)
 
     class C2NotGate(cirq.Gate):
         def _qid_shape_(self):
             return (3, 2)
 
-    class IdentityGate(cirq.SingleQubitGate):
+    class IdentityGate(cirq.testing.SingleQubitGate):
         def _qid_shape_(self):
             return (1,)
 
@@ -1987,13 +1987,13 @@ def test_to_text_diagram_teleportation_to_diagram(circuit_cls):
 
 @pytest.mark.parametrize('circuit_cls', [cirq.Circuit, cirq.FrozenCircuit])
 def test_diagram_with_unknown_exponent(circuit_cls):
-    class WeirdGate(cirq.SingleQubitGate):
+    class WeirdGate(cirq.testing.SingleQubitGate):
         def _circuit_diagram_info_(
             self, args: cirq.CircuitDiagramInfoArgs
         ) -> cirq.CircuitDiagramInfo:
             return cirq.CircuitDiagramInfo(wire_symbols=('B',), exponent='fancy')
 
-    class WeirderGate(cirq.SingleQubitGate):
+    class WeirderGate(cirq.testing.SingleQubitGate):
         def _circuit_diagram_info_(
             self, args: cirq.CircuitDiagramInfoArgs
         ) -> cirq.CircuitDiagramInfo:
@@ -2103,7 +2103,7 @@ def _circuit_diagram_info_(self, args: cirq.CircuitDiagramInfoArgs) -> Tuple[str
 def test_to_text_diagram_parameterized_value(circuit_cls):
     q = cirq.NamedQubit('cube')
 
-    class PGate(cirq.SingleQubitGate):
+    class PGate(cirq.testing.SingleQubitGate):
         def __init__(self, val):
             self.val = val
 
@@ -2266,10 +2266,10 @@ def test_diagram_global_phase(circuit_cls):
 
 @pytest.mark.parametrize('circuit_cls', [cirq.Circuit, cirq.FrozenCircuit])
 def test_has_unitary(circuit_cls):
-    class NonUnitary(cirq.SingleQubitGate):
+    class NonUnitary(cirq.testing.SingleQubitGate):
         pass
 
-    class EventualUnitary(cirq.SingleQubitGate):
+    class EventualUnitary(cirq.testing.SingleQubitGate):
         def _decompose_(self, qubits):
             return cirq.X.on_each(*qubits)
 
@@ -4098,7 +4098,7 @@ def test_indexing_by_numpy_integer(circuit_cls):
 
 @pytest.mark.parametrize('circuit_cls', [cirq.Circuit, cirq.FrozenCircuit])
 def test_all_measurement_key_names(circuit_cls):
-    class Unknown(cirq.SingleQubitGate):
+    class Unknown(cirq.testing.SingleQubitGate):
         def _measurement_key_name_(self):
             return 'test'
 

cirq/circuits/moment_test.py

@@ -574,10 +574,7 @@ def test_moment_text_diagram():
         xy_breakdown_func=lambda q: ('abc'[q.x], q.x),
     )
 
-    class EmptyGate(cirq.Gate):
-        def _num_qubits_(self) -> int:
-            return 1
-
+    class EmptyGate(cirq.testing.SingleQubitGate):
         def __str__(self):
             return 'Empty'
 
@@ -701,9 +698,8 @@ def test_kraus_too_big():
 
 
 def test_op_has_no_kraus():
-    class EmptyGate(cirq.Gate):
-        def _num_qubits_(self) -> int:
-            return 1
+    class EmptyGate(cirq.testing.SingleQubitGate):
+        pass
 
     m = cirq.Moment(EmptyGate().on(cirq.NamedQubit("a")))
     assert not cirq.has_kraus(m)

cirq/circuits/qasm_output.py

@@ -26,7 +26,7 @@
 
 
 @value.value_equality(approximate=True)
-class QasmUGate(ops.SingleQubitGate):
+class QasmUGate(ops.Gate):
     def __init__(self, theta, phi, lmda) -> None:
         """A QASM gate representing any single qubit unitary with a series of
         three rotations, Z, Y, and Z.
@@ -42,6 +42,9 @@ def __init__(self, theta, phi, lmda) -> None:
         self.theta = theta % 2
         self.phi = phi % 2
 
+    def _num_qubits_(self) -> int:
+        return 1
+
     @staticmethod
     def from_matrix(mat: np.ndarray) -> 'QasmUGate':
         pre_phase, rotation, post_phase = linalg.deconstruct_single_qubit_matrix_into_angles(mat)

cirq/circuits/quil_output.py

@@ -25,7 +25,7 @@ def to_quil_complex_format(num) -> str:
 
 
 @value.value_equality(approximate=True)
-class QuilOneQubitGate(ops.SingleQubitGate):
+class QuilOneQubitGate(ops.Gate):
     """A QUIL gate representing any single qubit unitary with a DEFGATE and
     2x2 matrix in QUIL.
     """
@@ -38,6 +38,9 @@ def __init__(self, matrix: np.ndarray) -> None:
         """
         self.matrix = matrix
 
+    def _num_qubits_(self) -> int:
+        return 1
+
     def _quil_(self, qubits: Tuple['cirq.Qid', ...], formatter: 'cirq.QuilFormatter') -> str:
         return (
             f'DEFGATE USERGATE:\n    '

cirq/contrib/qasm_import/_parser_test.py

@@ -429,7 +429,7 @@ def test_unknown_function():
 
 
 @pytest.mark.parametrize('qasm_gate,cirq_gate', rotation_gates)
-def test_rotation_gates(qasm_gate: str, cirq_gate: cirq.SingleQubitGate):
+def test_rotation_gates(qasm_gate: str, cirq_gate: cirq.Gate):
     qasm = """OPENQASM 2.0;
      include "qelib1.inc";
      qreg q[2];
@@ -989,7 +989,7 @@ def test_three_qubit_gates_with_too_much_parameters(qasm_gate: str):
 
 
 @pytest.mark.parametrize('qasm_gate,cirq_gate', single_qubit_gates)
-def test_single_qubit_gates(qasm_gate: str, cirq_gate: cirq.SingleQubitGate):
+def test_single_qubit_gates(qasm_gate: str, cirq_gate: cirq.Gate):
     qasm = """OPENQASM 2.0;
      include "qelib1.inc";
      qreg q[2];

cirq/contrib/quirk/export_to_quirk_test.py

@@ -177,7 +177,7 @@ def with_qubits(self, *new_qubits):
         return MysteryOperation(*new_qubits)
 
 
-class MysteryGate(cirq.SingleQubitGate):
+class MysteryGate(cirq.testing.SingleQubitGate):
     pass
 
 
@@ -279,7 +279,7 @@ def test_unrecognized_single_qubit_gate_with_matrix():
 
 
 def test_unknown_gate():
-    class UnknownGate(cirq.SingleQubitGate):
+    class UnknownGate(cirq.testing.SingleQubitGate):
         pass
 
     a = cirq.NamedQubit('a')

cirq/devices/noise_model.py

@@ -264,7 +264,7 @@ def noisy_moment(
     """,
 )
 
-NOISE_MODEL_LIKE = Union[None, 'cirq.NoiseModel', 'cirq.SingleQubitGate']
+NOISE_MODEL_LIKE = Union[None, 'cirq.NoiseModel', 'cirq.Gate']
 document(
     NOISE_MODEL_LIKE,  # type: ignore
     """A `cirq.NoiseModel` or a value that can be trivially converted into one.

cirq/experiments/cross_entropy_benchmarking.py

@@ -284,7 +284,7 @@ def cross_entropy_benchmarking(
     num_circuits: int = 20,
     repetitions: int = 1000,
     cycles: Union[int, Iterable[int]] = range(2, 103, 10),
-    scrambling_gates_per_cycle: List[List[ops.SingleQubitGate]] = None,
+    scrambling_gates_per_cycle: List[List[ops.Gate]] = None,
     simulator: sim.Simulator = None,
 ) -> CrossEntropyResult:
     r"""Cross-entropy benchmarking (XEB) of multiple qubits.
@@ -482,7 +482,7 @@ def build_entangling_layers(
 def _build_xeb_circuits(
     qubits: Sequence[ops.Qid],
     cycles: Sequence[int],
-    single_qubit_gates: List[List[ops.SingleQubitGate]] = None,
+    single_qubit_gates: List[List[ops.Gate]] = None,
     benchmark_ops: Sequence[circuits.Moment] = None,
 ) -> List[circuits.Circuit]:
     if benchmark_ops is not None:
@@ -570,7 +570,7 @@ def _random_half_rotations(qubits: Sequence[ops.Qid], num_layers: int) -> List[L
 
 
 def _random_any_gates(
-    qubits: Sequence[ops.Qid], op_list: List[List[ops.SingleQubitGate]], num_layers: int
+    qubits: Sequence[ops.Qid], op_list: List[List[ops.Gate]], num_layers: int
 ) -> List[List[ops.OP_TREE]]:
     num_ops = len(op_list)
     num_qubits = len(qubits)

cirq/interop/quirk/cells/control_cells.py

@@ -132,7 +132,7 @@ def generate_all_control_cell_makers() -> Iterator[CellMaker]:
     yield _reg_parity_control("zpar", basis_change=None)
 
 
-def _reg_control(identifier: str, *, basis_change: Optional['cirq.SingleQubitGate']) -> CellMaker:
+def _reg_control(identifier: str, *, basis_change: Optional['cirq.Gate']) -> CellMaker:
     return CellMaker(
         identifier=identifier,
         size=1,
@@ -143,7 +143,7 @@ def _reg_control(identifier: str, *, basis_change: Optional['cirq.SingleQubitGat
 
 
 def _reg_parity_control(
-    identifier: str, *, basis_change: Optional['cirq.SingleQubitGate'] = None
+    identifier: str, *, basis_change: Optional['cirq.Gate'] = None
 ) -> CellMaker:
     return CellMaker(
         identifier=identifier,
@@ -155,7 +155,7 @@ def _reg_parity_control(
 
 
 def _basis_else_empty(
-    basis_change: Optional['cirq.SingleQubitGate'], qureg: Union['cirq.Qid', Iterable['cirq.Qid']]
+    basis_change: Optional['cirq.Gate'], qureg: Union['cirq.Qid', Iterable['cirq.Qid']]
 ) -> Iterable['cirq.Operation']:
     if basis_change is None:
         return ()

cirq/ion/convert_to_ion_gates_test.py

@@ -19,12 +19,12 @@
 import cirq
 
 
-class OtherX(cirq.SingleQubitGate):
+class OtherX(cirq.testing.SingleQubitGate):
     def _unitary_(self) -> np.ndarray:
         return np.array([[0, 1], [1, 0]])
 
 
-class NoUnitary(cirq.SingleQubitGate):
+class NoUnitary(cirq.testing.SingleQubitGate):
     pass
 
 

cirq/ion/ion_device_test.py

@@ -53,8 +53,8 @@ def test_init():
     assert d.duration_of(cirq.measure(q0)) == 100 * ms
     assert d.duration_of(cirq.measure(q0, q1)) == 100 * ms
     assert d.duration_of(cirq.ops.XX(q0, q1)) == 200 * ms
-    with pytest.raises(ValueError):
-        _ = d.duration_of(cirq.SingleQubitGate().on(q0))
+    with pytest.raises(ValueError, match="Unsupported gate type"):
+        _ = d.duration_of(cirq.I(q0))
 
     with pytest.raises(TypeError, match="NamedQubit"):
         _ = cirq.IonDevice(
@@ -86,7 +86,7 @@ def test_init_timedelta():
     assert d.duration_of(cirq.measure(q0, q1)) == 100 * ms
     assert d.duration_of(cirq.ops.XX(q0, q1)) == 200 * ms
     with pytest.raises(ValueError):
-        _ = d.duration_of(cirq.SingleQubitGate().on(q0))
+        _ = d.duration_of(cirq.testing.SingleQubitGate().on(q0))
 
 
 def test_decomposition_deprecated():

cirq/neutral_atoms/convert_to_neutral_atom_gates_test.py

@@ -50,11 +50,11 @@ def with_qubits(self, *new_qubits):
 
 
 def test_avoids_decompose_fallback_when_matrix_available_single_qubit():
-    class OtherX(cirq.SingleQubitGate):
+    class OtherX(cirq.testing.SingleQubitGate):
         def _unitary_(self) -> np.ndarray:
             return np.array([[0, 1], [1, 0]])
 
-    class OtherOtherX(cirq.SingleQubitGate):
+    class OtherOtherX(cirq.testing.SingleQubitGate):
         def _decompose_(self, qubits):
             return OtherX().on(*qubits)
 

cirq/neutral_atoms/neutral_atom_devices_test.py

@@ -53,7 +53,7 @@ def test_init():
     assert d.duration_of(cirq.GateOperation(cirq.IdentityGate(1), [q00])) == 100 * us
     assert d.duration_of(cirq.measure(q00)) == 50 * ms
     with pytest.raises(ValueError):
-        _ = d.duration_of(cirq.SingleQubitGate().on(q00))
+        _ = d.duration_of(cirq.testing.SingleQubitGate().on(q00))
 
 
 def test_metadata():
@@ -83,7 +83,7 @@ def test_init_timedelta():
     assert d.duration_of(cirq.GateOperation(cirq.IdentityGate(1), [q00])) == 100 * us
     assert d.duration_of(cirq.measure(q00)) == 50 * ms
     with pytest.raises(ValueError):
-        _ = d.duration_of(cirq.SingleQubitGate().on(q00))
+        _ = d.duration_of(cirq.testing.SingleQubitGate().on(q00))
 
 
 def test_init_errors():
@@ -126,7 +126,7 @@ def test_validate_gate_errors():
     with pytest.raises(ValueError, match="controlled gates must have integer exponents"):
         d.validate_gate(cirq.CNotPowGate(exponent=0.5))
     with pytest.raises(ValueError, match="Unsupported gate"):
-        d.validate_gate(cirq.SingleQubitGate())
+        d.validate_gate(cirq.testing.SingleQubitGate())
 
 
 def test_validate_operation_errors():

cirq/ops/clifford_gate.py

@@ -127,7 +127,7 @@ def _validate_map_input(
 def _pad_tableau(
     clifford_tableau: qis.CliffordTableau, num_qubits_after_padding: int, axes: List[int]
 ) -> qis.CliffordTableau:
-    """Roughly, this function copies self.tabluea into the "identity" matrix."""
+    """Roughly, this function copies self.tableau into the "identity" matrix."""
     # Sanity check
     if len(set(axes)) != clifford_tableau.n:
         raise ValueError(