Transpile to native IonQ gates (#6572)

* add ionq native gate cirq_ionq.ZZGate
* add ionq native gatesets AriaNativeGateset, ForteNativeGateset
* support JSON serialization for the ZZGate and new gatesets

Author: radumarg

cirq-ionq/cirq_ionq/__init__.py

@@ -23,6 +23,11 @@
     decompose_all_to_all_connect_ccz_gate as decompose_all_to_all_connect_ccz_gate,
 )
 
+from cirq_ionq.ionq_native_target_gateset import (
+    AriaNativeGateset as AriaNativeGateset,
+    ForteNativeGateset as ForteNativeGateset,
+)
+
 from cirq_ionq.ionq_exceptions import (
     IonQException as IonQException,
     IonQNotFoundException as IonQNotFoundException,
@@ -39,7 +44,12 @@
 
 from cirq_ionq.service import Service as Service
 
-from cirq_ionq.ionq_native_gates import GPIGate as GPIGate, GPI2Gate as GPI2Gate, MSGate as MSGate
+from cirq_ionq.ionq_native_gates import (
+    GPIGate as GPIGate,
+    GPI2Gate as GPI2Gate,
+    MSGate as MSGate,
+    ZZGate as ZZGate,
+)
 
 from cirq.protocols.json_serialization import _register_resolver
 from cirq_ionq.json_resolver_cache import _class_resolver_dictionary

cirq-ionq/cirq_ionq/ionq_native_gates.py

@@ -17,10 +17,11 @@
 
 import cmath
 import math
+import numpy as np
+
 import cirq
 from cirq import protocols
 from cirq._doc import document
-import numpy as np
 
 
 @cirq.value.value_equality
@@ -270,3 +271,92 @@ def __pow__(self, power):
     See [IonQ best practices](https://ionq.com/docs/getting-started-with-native-gates){:external}.
     """,
 )
+
+
+@cirq.value.value_equality
+class ZZGate(cirq.Gate):
+    r"""The ZZ gate is another two qubit gate native to trapped ions. The ZZ gate only
+    requires a single parameter, θ, to set the phase of the entanglement.
+
+    The unitary matrix of this gate using the parameter $\theta$ is:
+
+    $$
+    \begin{bmatrix}
+        e{-i\pi\theta} & 0 & 0 & 0 \\
+        0 & e{i\pi\theta} & 0 & 0 \\
+        0 & 0 & e{i\pi\theta} & 0 \\
+        0 & 0 & 0 & e{-i\pi\theta}
+    \end{bmatrix}
+    $$
+
+    See [IonQ best practices](https://ionq.com/docs/getting-started-with-native-gates){:external}.
+    """
+
+    def __init__(self, *, theta):
+        self.theta = theta
+
+    def _unitary_(self) -> np.ndarray:
+        theta = self.theta
+
+        return np.array(
+            [
+                [cmath.exp(-1j * theta * math.pi), 0, 0, 0],
+                [0, cmath.exp(1j * theta * math.pi), 0, 0],
+                [0, 0, cmath.exp(1j * theta * math.pi), 0],
+                [0, 0, 0, cmath.exp(-1j * theta * math.pi)],
+            ]
+        )
+
+    @property
+    def phase(self) -> float:
+        return self.theta
+
+    def __str__(self) -> str:
+        return 'ZZ'
+
+    def _num_qubits_(self) -> int:
+        return 2
+
+    def _circuit_diagram_info_(
+        self, args: 'cirq.CircuitDiagramInfoArgs'
+    ) -> Union[str, 'protocols.CircuitDiagramInfo']:
+        return protocols.CircuitDiagramInfo(wire_symbols=(f'ZZ({self.theta!r})', 'ZZ'))
+
+    def __repr__(self) -> str:
+        return f'cirq_ionq.ZZGate(theta={self.theta!r})'
+
+    def _json_dict_(self) -> Dict[str, Any]:
+        return cirq.obj_to_dict_helper(self, ['theta'])
+
+    def _value_equality_values_(self) -> Any:
+        return self.theta
+
+    def __pow__(self, power):
+        if power == 1:
+            return self
+
+        if power == -1:
+            return ZZGate(theta=-self.theta)
+
+        return NotImplemented
+
+
+ZZ = ZZGate(theta=0)
+document(
+    ZZ,
+    r"""An instance of the two qubit ZZ gate with no phase.
+
+    The unitary matrix of this gate for parameters $\theta$ is
+
+    $$
+    \begin{bmatrix}
+        1 & 0 & 0 & 0 \\
+        0 & 1 & 0 & 0 \\
+        0 & 0 & 1 & 0 \\
+        0 & 0 & 0 & 1 \\
+    \end{bmatrix}
+    $$
+
+    See [IonQ best practices](https://ionq.com/docs/getting-started-with-native-gates){:external}.
+    """,
+)

cirq-ionq/cirq_ionq/ionq_native_gates_test.py

@@ -13,23 +13,15 @@
 # limitations under the License.
 """Tests for IonQ native gates"""
 
-import math
 import cirq
 import numpy
 import pytest
 
 import cirq_ionq as ionq
 
 
-PARAMS_FOR_ONE_ANGLE_GATE = [0, 0.1, 0.4, math.pi / 2, math.pi, 2 * math.pi]
-PARAMS_FOR_TWO_ANGLE_GATE = [
-    (0, 1),
-    (0.1, 1),
-    (0.4, 1),
-    (math.pi / 2, 0),
-    (0, math.pi),
-    (0.1, 2 * math.pi),
-]
+PARAMS_FOR_ONE_ANGLE_GATE = [0, 0.1, 0.4, 0.5, 1, 2]
+PARAMS_FOR_TWO_ANGLE_GATE = [(0, 1), (0.1, 1), (0.4, 1), (0.5, 0), (0, 1), (0.1, 2)]
 INVALID_GATE_POWER = [-2, -0.5, 0, 0.5, 2]
 
 
@@ -39,6 +31,7 @@
         (ionq.GPIGate(phi=0.1), 1, "0: ───GPI(0.1)───"),
         (ionq.GPI2Gate(phi=0.2), 1, "0: ───GPI2(0.2)───"),
         (ionq.MSGate(phi0=0.1, phi1=0.2), 2, "0: ───MS(0.1)───\n      │\n1: ───MS(0.2)───"),
+        (ionq.ZZGate(theta=0.3), 2, "0: ───ZZ(0.3)───\n      │\n1: ───ZZ────────"),
     ],
 )
 def test_gate_methods(gate, nqubits, diagram):
@@ -52,14 +45,20 @@ def test_gate_methods(gate, nqubits, diagram):
 
 
 @pytest.mark.parametrize(
-    "gate", [ionq.GPIGate(phi=0.1), ionq.GPI2Gate(phi=0.2), ionq.MSGate(phi0=0.1, phi1=0.2)]
+    "gate",
+    [
+        ionq.GPIGate(phi=0.1),
+        ionq.GPI2Gate(phi=0.2),
+        ionq.MSGate(phi0=0.1, phi1=0.2),
+        ionq.ZZGate(theta=0.4),
+    ],
 )
 def test_gate_json(gate):
     g_json = cirq.to_json(gate)
     assert cirq.read_json(json_text=g_json) == gate
 
 
-@pytest.mark.parametrize("phase", [0, 0.1, 0.4, math.pi / 2, math.pi, 2 * math.pi])
+@pytest.mark.parametrize("phase", [0, 0.1, 0.4, 0.5, 1, 2])
 def test_gpi_unitary(phase):
     """Tests that the GPI gate is unitary."""
     gate = ionq.GPIGate(phi=phase)
@@ -68,7 +67,7 @@ def test_gpi_unitary(phase):
     numpy.testing.assert_array_almost_equal(mat.dot(mat.conj().T), numpy.identity(2))
 
 
-@pytest.mark.parametrize("phase", [0, 0.1, 0.4, math.pi / 2, math.pi, 2 * math.pi])
+@pytest.mark.parametrize("phase", [0, 0.1, 0.4, 0.5, 1, 2])
 def test_gpi2_unitary(phase):
     """Tests that the GPI2 gate is unitary."""
     gate = ionq.GPI2Gate(phi=phase)
@@ -77,9 +76,7 @@ def test_gpi2_unitary(phase):
     numpy.testing.assert_array_almost_equal(mat.dot(mat.conj().T), numpy.identity(2))
 
 
-@pytest.mark.parametrize(
-    "phases", [(0, 1), (0.1, 1), (0.4, 1), (math.pi / 2, 0), (0, math.pi), (0.1, 2 * math.pi)]
-)
+@pytest.mark.parametrize("phases", [(0, 1), (0.1, 1), (0.4, 1), (0.5, 0), (0, 1), (0.1, 2)])
 def test_ms_unitary(phases):
     """Tests that the MS gate is unitary."""
     gate = ionq.MSGate(phi0=phases[0], phi1=phases[1])
@@ -88,12 +85,22 @@ def test_ms_unitary(phases):
     numpy.testing.assert_array_almost_equal(mat.dot(mat.conj().T), numpy.identity(4))
 
 
+@pytest.mark.parametrize("phase", [0, 0.1, 0.4, 0.5, 1, 2])
+def test_zz_unitary(phase):
+    """Tests that the ZZ gate is unitary."""
+    gate = ionq.ZZGate(theta=phase)
+
+    mat = cirq.protocols.unitary(gate)
+    numpy.testing.assert_array_almost_equal(mat.dot(mat.conj().T), numpy.identity(4))
+
+
 @pytest.mark.parametrize(
     "gate",
     [
         *[ionq.GPIGate(phi=angle) for angle in PARAMS_FOR_ONE_ANGLE_GATE],
         *[ionq.GPI2Gate(phi=angle) for angle in PARAMS_FOR_ONE_ANGLE_GATE],
         *[ionq.MSGate(phi0=angles[0], phi1=angles[1]) for angles in PARAMS_FOR_TWO_ANGLE_GATE],
+        *[ionq.ZZGate(theta=angle) for angle in PARAMS_FOR_ONE_ANGLE_GATE],
     ],
 )
 def test_gate_inverse(gate):
@@ -110,6 +117,7 @@ def test_gate_inverse(gate):
     [
         *[ionq.GPIGate(phi=angle) for angle in PARAMS_FOR_ONE_ANGLE_GATE],
         *[ionq.GPI2Gate(phi=angle) for angle in PARAMS_FOR_ONE_ANGLE_GATE],
+        *[ionq.ZZGate(theta=angle) for angle in PARAMS_FOR_ONE_ANGLE_GATE],
         *[ionq.MSGate(phi0=angles[0], phi1=angles[1]) for angles in PARAMS_FOR_TWO_ANGLE_GATE],
     ],
 )
@@ -127,6 +135,7 @@ def test_gate_power1(gate):
         *[(ionq.GPIGate(phi=0.1), power) for power in INVALID_GATE_POWER],
         *[(ionq.GPI2Gate(phi=0.1), power) for power in INVALID_GATE_POWER],
         *[(ionq.MSGate(phi0=0.1, phi1=0.2), power) for power in INVALID_GATE_POWER],
+        *[(ionq.ZZGate(theta=0.1), power) for power in INVALID_GATE_POWER],
     ],
 )
 def test_gate_power_not_implemented(gate, power):