Update AQT Backend (#6441)

Adjusted the AQT backend so that it works with the new AQT Arnica API. We also updated the gateset to reflect what we support.
As we made an extension to the API, we were able to add a feature that lists the workspaces and resources that are available to a user. We also updated tests and documentation accordingly.

Fixes #6379

Author: jbrixon

cirq-aqt/cirq_aqt/aqt_device.py

@@ -25,6 +25,7 @@
 """
 
 import json
+from enum import Enum
 from typing import Any, cast, Dict, Iterable, List, Optional, Sequence, Set, Tuple, Union
 
 import networkx as nx
@@ -36,11 +37,27 @@
 gate_dict = {'X': cirq.X, 'Y': cirq.Y, 'Z': cirq.Z, 'MS': cirq.XX, 'R': cirq.PhasedXPowGate}
 
 
+class OperationString(Enum):
+    """String representations of operations supported by AQT resources."""
+
+    MS = "MS"
+    """Cirq: XXPowGate, AQT: RXX gate."""
+
+    Z = "Z"
+    """Cirq: ZPowGate, AQT: RZ gate."""
+
+    R = "R"
+    """Cirq: PhasedXPowGate, AQT: R gate."""
+
+    MEASURE = "Meas"
+    """Measurement gate."""
+
+
 def get_op_string(op_obj: cirq.Operation) -> str:
     """Find the string representation for a given gate or operation.
 
     Args:
-        op_obj: Gate or operation object. Gate must be one of: XXPowGate, XPowGate, YPowGate,
+        op_obj: Gate or operation object. Gate must be one of: XXPowGate,
             ZPowGate, PhasedXPowGate, or MeasurementGate.
 
     Returns:
@@ -50,20 +67,16 @@ def get_op_string(op_obj: cirq.Operation) -> str:
         ValueError: If the gate is not one of the supported gates.
     """
     if isinstance(op_obj.gate, cirq.XXPowGate):
-        op_str = 'MS'
-    elif isinstance(op_obj.gate, cirq.XPowGate):
-        op_str = 'X'
-    elif isinstance(op_obj.gate, cirq.YPowGate):
-        op_str = 'Y'
+        op_str = OperationString.MS.value
     elif isinstance(op_obj.gate, cirq.ZPowGate):
-        op_str = 'Z'
+        op_str = OperationString.Z.value
     elif isinstance(op_obj.gate, cirq.PhasedXPowGate):
-        op_str = 'R'
+        op_str = OperationString.R.value
     elif isinstance(op_obj.gate, cirq.MeasurementGate):
-        op_str = 'Meas'
+        op_str = OperationString.MEASURE.value
     else:
         raise ValueError(f'Got unknown gate on operation: {op_obj}.')
-    return op_str
+    return str(op_str)
 
 
 class AQTNoiseModel(cirq.NoiseModel):
@@ -97,6 +110,7 @@ def noisy_moment(
             for qubit in op.qubits:
                 noise_list.append(noise_op.on(qubit))
             noise_list += self.get_crosstalk_operation(op, system_qubits)
+
         return list(moment) + noise_list
 
     def get_crosstalk_operation(
@@ -122,16 +136,18 @@ def get_crosstalk_operation(
             for neigh_idx in neighbors:
                 if neigh_idx >= 0 and neigh_idx < num_qubits:
                     xtlk_arr[neigh_idx] = self.noise_op_dict['crosstalk']
+
         for idx in idx_list:
             xtlk_arr[idx] = 0
         xtlk_op_list = []
         op_str = get_op_string(operation)
         gate = cast(cirq.EigenGate, gate_dict[op_str])
+
         if len(operation.qubits) == 1:
             for idx in xtlk_arr.nonzero()[0]:
                 exponent = operation.gate.exponent  # type:ignore
                 exponent = exponent * xtlk_arr[idx]
-                xtlk_op = gate.on(system_qubits[idx]) ** exponent
+                xtlk_op = operation.gate.on(system_qubits[idx]) ** exponent  # type:ignore
                 xtlk_op_list.append(xtlk_op)
         elif len(operation.qubits) == 2:
             for op_qubit in operation.qubits:
@@ -216,10 +232,14 @@ def simulate_samples(self, repetitions: int) -> cirq.Result:
             noise_model = cirq.NO_NOISE
         else:
             noise_model = AQTNoiseModel()
+
         if self.circuit == cirq.Circuit():
             raise RuntimeError('Simulate called without a valid circuit.')
+
         sim = cirq.DensityMatrixSimulator(noise=noise_model)
+
         result = sim.run(self.circuit, repetitions=repetitions)
+
         return result
 
 
@@ -342,10 +362,9 @@ def get_aqt_device(num_qubits: int) -> Tuple[AQTDevice, List[cirq.LineQubit]]:
 def get_default_noise_dict() -> Dict[str, Any]:
     """Returns the current noise parameters"""
     default_noise_dict = {
-        'X': cirq.depolarize(1e-3),
-        'Y': cirq.depolarize(1e-3),
-        'Z': cirq.depolarize(1e-3),
-        'MS': cirq.depolarize(1e-2),
+        OperationString.R.value: cirq.depolarize(1e-3),
+        OperationString.Z.value: cirq.depolarize(0),
+        OperationString.MS.value: cirq.depolarize(1e-2),
         'crosstalk': 0.03,
     }
     return default_noise_dict

cirq-aqt/cirq_aqt/aqt_device_metadata.py

@@ -53,8 +53,6 @@ def __init__(
         self._gate_durations = {
             cirq.GateFamily(cirq.MeasurementGate): self._measurement_duration,
             cirq.GateFamily(cirq.XXPowGate): self._twoq_gates_duration,
-            cirq.GateFamily(cirq.XPowGate): self._oneq_gates_duration,
-            cirq.GateFamily(cirq.YPowGate): self._oneq_gates_duration,
             cirq.GateFamily(cirq.ZPowGate): self._oneq_gates_duration,
             cirq.GateFamily(cirq.PhasedXPowGate): self._oneq_gates_duration,
         }

cirq-aqt/cirq_aqt/aqt_device_metadata_test.py

@@ -45,7 +45,7 @@ def test_aqtdevice_metadata(metadata, qubits):
     assert len(edges) == 10
     assert all(q0 != q1 for q0, q1 in edges)
     assert AQTTargetGateset() == metadata.gateset
-    assert len(metadata.gate_durations) == 6
+    assert len(metadata.gate_durations) == 4
 
 
 def test_aqtdevice_duration_of(metadata, qubits):