Deprecate cirq.ion module (quantumlib#5563)

Fixes quantumlib#2793
Fixes quantumlib#5128

cirq/ion/convert_to_ion_gates.py

@@ -14,10 +14,17 @@
 
 import numpy as np
 
-from cirq import ops, protocols, circuits, transformers
+from cirq import _compat, ops, protocols, circuits, transformers
 from cirq.ion import ms, two_qubit_matrix_to_ion_operations, ion_device
 
 
+@_compat.deprecated_class(
+    deadline='v0.16',
+    fix='Use cirq.optimize_for_target_gateset('
+    'circuit, '
+    'gateset=cirq_aqt.aqt_device.AQTTargetGateset()'
+    ').',
+)
 class ConvertToIonGates:
     """Attempts to convert non-native gates into IonGates."""
 
@@ -30,7 +37,7 @@ def __init__(self, ignore_failures: bool = False) -> None:
         """
         super().__init__()
         self.ignore_failures = ignore_failures
-        self.gateset = ion_device.get_ion_gateset()
+        self.gateset = ion_device._IonTargetGateset()
 
     def convert_one(self, op: ops.Operation) -> ops.OP_TREE:
         """Convert a single (one- or two-qubit) operation into ion trap native gates.

cirq/ion/convert_to_ion_gates_test.py

@@ -38,21 +38,38 @@ def test_convert_to_ion_gates():
     q1 = cirq.GridQubit(0, 1)
     op = cirq.CNOT(q0, q1)
     circuit = cirq.Circuit()
+    ion_gateset = cirq.ion.ion_device._IonTargetGateset()
+    with cirq.testing.assert_deprecated(
+        "cirq_aqt.aqt_device.AQTTargetGateset", deadline='v0.16', count=None
+    ):
+        convert_to_ion_gates = cirq.ion.ConvertToIonGates()
 
     with pytest.raises(TypeError):
-        cirq.ion.ConvertToIonGates().convert_one(circuit)
-
-    with pytest.raises(TypeError):
-        cirq.ion.ConvertToIonGates().convert_one(NoUnitary().on(q0))
+        convert_to_ion_gates.convert_one(circuit)
 
     no_unitary_op = NoUnitary().on(q0)
-    assert cirq.ion.ConvertToIonGates(ignore_failures=True).convert_one(no_unitary_op) == [
-        no_unitary_op
-    ]
-
-    rx = cirq.ion.ConvertToIonGates().convert_one(OtherX().on(q0))
-    rop = cirq.ion.ConvertToIonGates().convert_one(op)
+    with pytest.raises(TypeError):
+        convert_to_ion_gates.convert_one(no_unitary_op)
+    assert ion_gateset._decompose_single_qubit_operation(no_unitary_op, 0) is NotImplemented
+
+    with cirq.testing.assert_deprecated(
+        "cirq_aqt.aqt_device.AQTTargetGateset", deadline='v0.16', count=None
+    ):
+        assert cirq.ion.ConvertToIonGates(ignore_failures=True).convert_one(no_unitary_op) == [
+            no_unitary_op
+        ]
+    rx = convert_to_ion_gates.convert_one(OtherX().on(q0))
+    rx_via_gateset = ion_gateset._decompose_single_qubit_operation(OtherX().on(q0), 0)
     assert cirq.approx_eq(rx, [cirq.PhasedXPowGate(phase_exponent=1.0).on(cirq.GridQubit(0, 0))])
+    assert cirq.approx_eq(
+        rx_via_gateset, [cirq.PhasedXPowGate(phase_exponent=1.0).on(cirq.GridQubit(0, 0))]
+    )
+
+    rop = convert_to_ion_gates.convert_one(op)
+    rop_via_gateset = ion_gateset._decompose_two_qubit_operation(op, 0)
+    cirq.testing.assert_circuits_with_terminal_measurements_are_equivalent(
+        cirq.Circuit(rop), cirq.Circuit(rop_via_gateset), atol=1e-6
+    )
     assert cirq.approx_eq(
         rop,
         [
@@ -64,7 +81,7 @@ def test_convert_to_ion_gates():
         ],
     )
 
-    rcnot = cirq.ion.ConvertToIonGates().convert_one(OtherCNOT().on(q0, q1))
+    rcnot = convert_to_ion_gates.convert_one(OtherCNOT().on(q0, q1))
     assert cirq.approx_eq(
         [op for op in rcnot if len(op.qubits) > 1],
         [cirq.ms(-0.5 * np.pi / 2).on(q0, q1)],
@@ -79,20 +96,36 @@ def test_convert_to_ion_circuit():
     q0 = cirq.LineQubit(0)
     q1 = cirq.LineQubit(1)
     us = cirq.Duration(nanos=1000)
-    ion_device = cirq.IonDevice(us, us, us, [q0, q1])
+    with cirq.testing.assert_deprecated("cirq_aqt.aqt_device.AQTDevice", deadline='v0.16', count=2):
+        ion_device = cirq.IonDevice(us, us, us, [q0, q1])
+    with cirq.testing.assert_deprecated(
+        "cirq_aqt.aqt_device.AQTTargetGateset", deadline='v0.16', count=None
+    ):
+        convert_to_ion_gates = cirq.ion.ConvertToIonGates()
 
     clifford_circuit_1 = cirq.Circuit()
     clifford_circuit_1.append([cirq.X(q0), cirq.H(q1), cirq.ms(np.pi / 4).on(q0, q1)])
-    ion_circuit_1 = cirq.ion.ConvertToIonGates().convert_circuit(clifford_circuit_1)
+    ion_circuit_1 = convert_to_ion_gates.convert_circuit(clifford_circuit_1)
+    ion_circuit_1_using_device = ion_device.decompose_circuit(clifford_circuit_1)
 
     ion_device.validate_circuit(ion_circuit_1)
+    ion_device.validate_circuit(ion_circuit_1_using_device)
     cirq.testing.assert_circuits_with_terminal_measurements_are_equivalent(
         clifford_circuit_1, ion_circuit_1, atol=1e-6
     )
+    cirq.testing.assert_circuits_with_terminal_measurements_are_equivalent(
+        clifford_circuit_1, ion_circuit_1_using_device, atol=1e-6
+    )
+
     clifford_circuit_2 = cirq.Circuit()
     clifford_circuit_2.append([cirq.X(q0), cirq.CNOT(q1, q0), cirq.ms(np.pi / 4).on(q0, q1)])
-    ion_circuit_2 = cirq.ion.ConvertToIonGates().convert_circuit(clifford_circuit_2)
+    ion_circuit_2 = convert_to_ion_gates.convert_circuit(clifford_circuit_2)
+    ion_circuit_2_using_device = ion_device.decompose_circuit(clifford_circuit_2)
     ion_device.validate_circuit(ion_circuit_2)
+    ion_device.validate_circuit(ion_circuit_2_using_device)
     cirq.testing.assert_circuits_with_terminal_measurements_are_equivalent(
         clifford_circuit_2, ion_circuit_2, atol=1e-6
     )
+    cirq.testing.assert_circuits_with_terminal_measurements_are_equivalent(
+        clifford_circuit_2, ion_circuit_2_using_device, atol=1e-6
+    )

cirq/ion/ion_device.py

@@ -12,32 +12,55 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Any, Iterable, Optional, Set, TYPE_CHECKING
+from typing import Any, Iterable, List, Optional, Set, TYPE_CHECKING
+import numpy as np
 import networkx as nx
-from cirq import circuits, value, devices, ops, protocols
-from cirq.ion import convert_to_ion_gates
+from cirq import _compat, circuits, value, devices, ops, protocols, transformers
+from cirq.protocols.decompose_protocol import DecomposeResult
 
 if TYPE_CHECKING:
     import cirq
 
 
-def get_ion_gateset() -> ops.Gateset:
-    return ops.Gateset(
-        ops.XXPowGate,
-        ops.MeasurementGate,
-        ops.XPowGate,
-        ops.YPowGate,
-        ops.ZPowGate,
-        ops.PhasedXPowGate,
-        unroll_circuit_op=False,
-    )
+class _IonTargetGateset(transformers.TwoQubitCompilationTargetGateset):
+    def __init__(self):
+        super().__init__(
+            ops.XXPowGate,
+            ops.MeasurementGate,
+            ops.XPowGate,
+            ops.YPowGate,
+            ops.ZPowGate,
+            ops.PhasedXPowGate,
+            unroll_circuit_op=False,
+        )
+
+    def _decompose_single_qubit_operation(self, op: 'cirq.Operation', _: int) -> DecomposeResult:
+        if isinstance(op.gate, ops.HPowGate) and op.gate.exponent == 1:
+            return [ops.rx(np.pi).on(op.qubits[0]), ops.ry(-1 * np.pi / 2).on(op.qubits[0])]
+        if protocols.has_unitary(op):
+            gates = transformers.single_qubit_matrix_to_phased_x_z(protocols.unitary(op))
+            return [g.on(op.qubits[0]) for g in gates]
+        return NotImplemented
+
+    def _decompose_two_qubit_operation(self, op: 'cirq.Operation', _) -> DecomposeResult:
+        if protocols.has_unitary(op):
+            return transformers.two_qubit_matrix_to_ion_operations(
+                op.qubits[0], op.qubits[1], protocols.unitary(op)
+            )
+        return NotImplemented
+
+    @property
+    def postprocess_transformers(self) -> List['cirq.TRANSFORMER']:
+        """List of transformers which should be run after decomposing individual operations."""
+        return [transformers.drop_negligible_operations, transformers.drop_empty_moments]
 
 
 @value.value_equality
-class IonDevice(devices.Device):
-    """A device with qubits placed on a line.
+class _IonDeviceImpl(devices.Device):
+    """Shared implementation of `cirq.IonDevice` (deprecated) and `cirq_aqt.AQTDevice`.
 
-    Qubits have all-to-all connectivity.
+    This class will be removed once `cirq.IonDevice` is deprecated and removed. The implementation
+    will be moved to `cirq_aqt.AQTDevice`.
     """
 
     def __init__(
@@ -68,7 +91,7 @@ def __init__(
                 f"{set(type(qubit) for qubit in qubits)}"
             )
         self.qubits = frozenset(qubits)
-        self.gateset = get_ion_gateset()
+        self.gateset = _IonTargetGateset()
 
         graph = nx.Graph()
         graph.add_edges_from([(a, b) for a in qubits for b in qubits if a != b], directed=False)
@@ -79,7 +102,7 @@ def metadata(self) -> devices.DeviceMetadata:
         return self._metadata
 
     def decompose_circuit(self, circuit: circuits.Circuit) -> circuits.Circuit:
-        return convert_to_ion_gates.ConvertToIonGates().convert_circuit(circuit)
+        return transformers.optimize_for_target_gateset(circuit, gateset=self.gateset)
 
     def duration_of(self, operation):
         if isinstance(operation.gate, ops.XXPowGate):
@@ -122,14 +145,6 @@ def neighbors_of(self, qubit: devices.LineQubit) -> Iterable[devices.LineQubit]:
         possibles = [devices.LineQubit(qubit.x + 1), devices.LineQubit(qubit.x - 1)]
         return [e for e in possibles if e in self.qubits]
 
-    def __repr__(self) -> str:
-        return (
-            f'IonDevice(measurement_duration={self._measurement_duration!r}, '
-            f'twoq_gates_duration={self._twoq_gates_duration!r}, '
-            f'oneq_gates_duration={self._oneq_gates_duration!r} '
-            f'qubits={sorted(self.qubits)!r})'
-        )
-
     def __str__(self) -> str:
         diagram = circuits.TextDiagramDrawer()
 
@@ -140,10 +155,6 @@ def __str__(self) -> str:
 
         return diagram.render(horizontal_spacing=3, vertical_spacing=2, use_unicode_characters=True)
 
-    def _repr_pretty_(self, p: Any, cycle: bool):
-        """iPython (Jupyter) pretty print."""
-        p.text("IonDevice(...)" if cycle else self.__str__())
-
     def _value_equality_values_(self) -> Any:
         return (
             self._measurement_duration,
@@ -162,3 +173,23 @@ def _verify_unique_measurement_keys(operations: Iterable[ops.Operation]):
             if key in seen:
                 raise ValueError(f'Measurement key {key} repeated')
             seen.add(key)
+
+
+@_compat.deprecated_class(deadline='v0.16', fix='Use cirq_aqt.aqt_device.AQTDevice.')
+class IonDevice(_IonDeviceImpl):
+    """A device with qubits placed on a line.
+
+    Qubits have all-to-all connectivity.
+    """
+
+    def __repr__(self) -> str:
+        return (
+            f'IonDevice(measurement_duration={self._measurement_duration!r}, '
+            f'twoq_gates_duration={self._twoq_gates_duration!r}, '
+            f'oneq_gates_duration={self._oneq_gates_duration!r} '
+            f'qubits={sorted(self.qubits)!r})'
+        )
+
+    def _repr_pretty_(self, p: Any, cycle: bool):
+        """iPython (Jupyter) pretty print."""
+        p.text("IonDevice(...)" if cycle else self.__str__())

cirq/ion/ion_device_test.py

@@ -19,16 +19,20 @@
 import cirq
 import cirq.ion as ci
 import cirq.testing
+import sympy.utilities.matchpy_connector
 
 
 def ion_device(chain_length: int, use_timedelta=False) -> ci.IonDevice:
     ms = 1000 * cirq.Duration(nanos=1) if not use_timedelta else timedelta(microseconds=1)
-    return ci.IonDevice(  # type: ignore
-        measurement_duration=100 * ms,  # type: ignore
-        twoq_gates_duration=200 * ms,  # type: ignore
-        oneq_gates_duration=10 * ms,  # type: ignore
-        qubits=cirq.LineQubit.range(chain_length),
-    )
+    with cirq.testing.assert_deprecated(
+        "Use cirq_aqt.aqt_device.AQTDevice", deadline='v0.16', count=None
+    ):
+        return ci.IonDevice(  # type: ignore
+            measurement_duration=100 * ms,  # type: ignore
+            twoq_gates_duration=200 * ms,  # type: ignore
+            oneq_gates_duration=10 * ms,  # type: ignore
+            qubits=cirq.LineQubit.range(chain_length),
+        )
 
 
 class NotImplementedOperation(cirq.Operation):
@@ -56,12 +60,13 @@ def test_init():
         _ = d.duration_of(cirq.I(q0))
 
     with pytest.raises(TypeError, match="NamedQubit"):
-        _ = cirq.IonDevice(
-            measurement_duration=ms,
-            twoq_gates_duration=ms,
-            oneq_gates_duration=ms,
-            qubits=[cirq.LineQubit(0), cirq.NamedQubit("a")],
-        )
+        with cirq.testing.assert_deprecated("Use cirq_aqt.aqt_device.AQTDevice", deadline='v0.16'):
+            _ = cirq.IonDevice(
+                measurement_duration=ms,
+                twoq_gates_duration=ms,
+                oneq_gates_duration=ms,
+                qubits=[cirq.LineQubit(0), cirq.NamedQubit("a")],
+            )
 
 
 def test_metadata():
@@ -178,3 +183,12 @@ def test_at():
     assert d.at(-1) is None
     assert d.at(0) == cirq.LineQubit(0)
     assert d.at(2) == cirq.LineQubit(2)
+
+
+def test_decompose_parameterized_gates():
+    theta = sympy.Symbol("theta")
+    q = cirq.LineQubit.range(2)
+    circuit = cirq.Circuit(cirq.H(q[0]) ** theta, cirq.XX(*q) ** theta)
+    d = ion_device(3)
+    assert d.gateset.validate(d.decompose_circuit(circuit))
+    assert d.gateset._decompose_two_qubit_operation(cirq.CZ(*q) ** theta, 0) is NotImplemented