fix: Only transpile natively if explicitly asked (#230)

Also added an `optimization_level` flag to `BraketAwsBackend.run` to give users an easy way to optimize their circuit when running.

Author: speller26

README.md

@@ -2,11 +2,9 @@
 
 [![Latest Version](https://img.shields.io/pypi/v/qiskit-braket-provider.svg)](https://pypi.python.org/pypi/qiskit-braket-provider)
 [![Supported Python Versions](https://img.shields.io/pypi/pyversions/qiskit-braket-provider.svg)](https://pypi.python.org/pypi/qiskit-braket-provider)
+[![Qiskit compatibility](https://img.shields.io/badge/Qiskit%20compatibility-%3E%3D0.34.2-blueviolet?logo=Qiskit)](https://github.com/Qiskit/qiskit/releases)
 [![Build status](https://github.com/qiskit-community/qiskit-braket-provider/actions/workflows/test_latest_versions.yml/badge.svg?branch=main)](https://github.com/qiskit-community/qiskit-braket-provider/actions/workflows/test_latest_versions.yml)
 
-[![Qiskit compatibility](https://img.shields.io/badge/Qiskit%20compatibility-%3E%3D0.34,%20%3C2.0-blueviolet?logo=Qiskit)](https://github.com/Qiskit/qiskit/releases)
-
-
 Qiskit-Braket provider to execute Qiskit programs on AWS quantum computing hardware devices through Amazon Braket.
 
 ### Table of Contents

qiskit_braket_provider/providers/__init__.py

@@ -6,18 +6,18 @@
 .. currentmodule:: qiskit_braket_provider.providers
 
 Provider module contains classes and functions to connect
-AWS Braket abstraction to Qiskit architecture.
+Amazon Braket abstraction to Qiskit architecture.
 
 Provider classes and functions
 ==============================
 
 .. autosummary::
     :toctree: ../stubs/
 
-    AWSBraketBackend
+    BraketAwsBackend
     BraketLocalBackend
-    AWSBraketProvider
-    AmazonBraketTask
+    BraketProvider
+    BraketQuantumTask
 """
 
 from .adapter import to_braket as to_braket

qiskit_braket_provider/providers/adapter.py

@@ -371,11 +371,10 @@ def aws_device_to_target(device: AwsDevice) -> Target:
             return _simulator_target(
                 f"Target for Amazon Braket simulator: {device.name}", device.properties
             )
-        case _:
-            raise QiskitBraketException(
-                "Cannot convert to target. "
-                f"{device.properties.__class__} device capabilities are not supported."
-            )
+    raise QiskitBraketException(
+        "Cannot convert to target. "
+        f"{device.properties.__class__} device capabilities are not supported."
+    )
 
 
 def _simulator_target(description: str, properties: GateModelSimulatorDeviceCapabilities):
@@ -498,8 +497,8 @@ def to_braket(
     angle_restrictions: dict[str, dict[int, set[float] | tuple[float, float]]] | None = None,
     *,
     target: Target | None = None,
-    braket_qubits: Sequence[int] | None = None,
-    optimization_level: int | None = 0,
+    qubit_labels: Sequence[int] | None = None,
+    optimization_level: int = 0,
 ) -> Circuit:
     """Return a Braket quantum circuit from a Qiskit quantum circuit.
 
@@ -518,11 +517,11 @@ def to_braket(
             validate numeric parameters. Default: `None`.
         target (Target | None): A backend transpiler target. Can only be provided
             if basis_gates is `None`. Default: `None`.
-        braket_qubits (Sequence[int] | None): A list of (not necessarily contiguous) indices of
+        qubit_labels (Sequence[int] | None): A list of (not necessarily contiguous) indices of
             qubits in the underlying Amazon Braket device. If not supplied, then the indices are
             assumed to be contiguous.
-        optimization_level (int | None): The optimization level to pass to `qiskit.transpile`.
-            Default: None.
+        optimization_level (int): The optimization level to pass to `qiskit.transpile`.
+            Default: 0 (no optimization).
 
     Returns:
         Circuit: Braket circuit
@@ -554,7 +553,7 @@ def to_braket(
     # Handle qiskit to braket conversion
     measured_qubits: dict[int, int] = {}
     braket_circuit = Circuit()
-    braket_qubits = braket_qubits or sorted(circuit.find_bit(q).index for q in circuit.qubits)
+    qubit_labels = qubit_labels or sorted(circuit.find_bit(q).index for q in circuit.qubits)
     for circuit_instruction in circuit.data:
         operation = circuit_instruction.operation
         qubits = circuit_instruction.qubits
@@ -568,7 +567,7 @@ def to_braket(
         match gate_name := operation.name:
             case "measure":
                 qubit = qubits[0]  # qubit count = 1 for measure
-                qubit_index = braket_qubits[circuit.find_bit(qubit).index]
+                qubit_index = qubit_labels[circuit.find_bit(qubit).index]
                 if qubit_index in measured_qubits.values():
                     raise ValueError(f"Cannot measure previously measured qubit {qubit_index}")
                 clbit = circuit.find_bit(circuit_instruction.clbits[0]).index
@@ -581,7 +580,7 @@ def to_braket(
                 )
             case "unitary" | "kraus":
                 params = _create_free_parameters(operation)
-                qubit_indices = [braket_qubits[circuit.find_bit(qubit).index] for qubit in qubits][
+                qubit_indices = [qubit_labels[circuit.find_bit(qubit).index] for qubit in qubits][
                     ::-1
                 ]  # reversal for little to big endian notation
 
@@ -597,7 +596,7 @@ def to_braket(
                 ):
                     raise ValueError("Negative control is not supported")
                 # Getting the index from the bit mapping
-                qubit_indices = [braket_qubits[circuit.find_bit(qubit).index] for qubit in qubits]
+                qubit_indices = [qubit_labels[circuit.find_bit(qubit).index] for qubit in qubits]
                 if intersection := set(measured_qubits.values()).intersection(qubit_indices):
                     raise ValueError(
                         f"Cannot apply operation {gate_name} to measured qubits {intersection}"
@@ -795,7 +794,7 @@ def _sympy_to_qiskit(expr: Mul | Add | Symbol | Pow) -> ParameterExpression | Pa
             return Parameter(expr.name)
         case Pow():
             return _sympy_to_qiskit(expr.args[0]) ** int(expr.args[1])
-        case obj if hasattr(obj, "is_number") and obj.is_real:
+        case obj if getattr(obj, "is_real", False):
             return float(obj)
     raise TypeError(f"unrecognized parameter type in conversion: {type(expr)}")
 

qiskit_braket_provider/providers/braket_backend.py

@@ -181,7 +181,7 @@ def run(self, run_input: QuantumCircuit | list[QuantumCircuit], **options) -> Br
 class BraketAwsBackend(BraketBackend[AwsDevice]):
     """BraketAwsBackend."""
 
-    def __init__(  # pylint: disable=too-many-positional-arguments
+    def __init__(
         self,
         arn: str | None = None,
         provider=None,
@@ -229,8 +229,10 @@ def __init__(  # pylint: disable=too-many-positional-arguments
             f"QiskitBraketProvider/{version.__version__}"
         )
         self._target = aws_device_to_target(device=self._device)
-        self._braket_qubits = (
-            sorted(self._device.topology_graph.nodes) if self._device.topology_graph else None
+        self._qubit_labels = (
+            tuple(sorted(self._device.topology_graph.nodes))
+            if self._device.topology_graph
+            else None
         )
         self._gateset = self.get_gateset()
         self._supports_program_sets = (
@@ -262,12 +264,21 @@ def target(self):
     def max_circuits(self):
         return None
 
+    @property
+    def qubit_labels(self) -> tuple[int, ...] | None:
+        """
+        tuple[int, ...] | None: The qubit labels of the underlying device, in ascending order.
+
+        Unlike the qubits in the target, these labels are not necessarily contiguous.
+        """
+        return self._qubit_labels
+
     @classmethod
     def _default_options(cls):
         return Options()
 
     def qubit_properties(self, qubit: int | list[int]) -> QubitProperties | list[QubitProperties]:
-        # TODO: fetch information from device.properties.provider  # pylint: disable=fixme
+        # TODO: fetch information from device.properties.provider
         raise NotImplementedError
 
     def queue_depth(self) -> QueueDepthInfo:
@@ -325,9 +336,15 @@ def acquire_channel(self, qubit: int):
     def control_channel(self, qubits: Iterable[int]):
         raise NotImplementedError(f"Control channel is not supported by {self.name}.")
 
-    def run(self, run_input, verbatim: bool = False, native: bool | None = None, **options):
-        # Defaults to native transpilation if the underlying device is a QPU
-        native = native if native is not None else self._device.type == AwsDeviceType.QPU
+    def run(
+        self,
+        run_input: QuantumCircuit | list[QuantumCircuit],
+        verbatim: bool = False,
+        native: bool = False,
+        *,
+        optimization_level: int = 0,
+        **options,
+    ):
         if isinstance(run_input, QuantumCircuit):
             circuits = [run_input]
         elif isinstance(run_input, list):
@@ -339,17 +356,25 @@ def run(self, run_input, verbatim: bool = False, native: bool | None = None, **o
             self._validate_meas_level(options["meas_level"])
             del options["meas_level"]
 
+        # Always use target for simulator
+        target, basis_gates = (
+            (self._target, None)
+            if native or self._device.type == AwsDeviceType.SIMULATOR
+            else (None, self._gateset)
+        )
         braket_circuits = (
-            [to_braket(circ, verbatim=True, braket_qubits=self._braket_qubits) for circ in circuits]
+            [to_braket(circ, verbatim=True, qubit_labels=self._qubit_labels) for circ in circuits]
             if verbatim
             else [
                 to_braket(
                     circ,
-                    target=self._target,
-                    braket_qubits=self._braket_qubits,
+                    target=target,
+                    basis_gates=basis_gates,
+                    qubit_labels=self._qubit_labels,
                     angle_restrictions=(
                         native_angle_restrictions(self._device.properties) if native else None
                     ),
+                    optimization_level=optimization_level,
                 )
                 for circ in circuits
             ]
@@ -376,7 +401,7 @@ def __init_subclass__(cls, **kwargs):
         warnings.warn(f"{cls.__name__} is deprecated.", DeprecationWarning, stacklevel=2)
         super().__init_subclass__(**kwargs)
 
-    def __init__(  # pylint: disable=too-many-positional-arguments
+    def __init__(
         self,
         device: AwsDevice,
         provider=None,

tests/providers/test_braket_backend.py

@@ -1,7 +1,7 @@
 """Tests for AWS Braket backends."""
 
 import unittest
-from unittest import TestCase, skip
+from unittest import TestCase
 from unittest.mock import Mock, patch
 
 import numpy as np
@@ -216,12 +216,15 @@ def test_run_multiple_circuits(self):
         circuit.h(0)
 
         backend.run([circuit, circuit], shots=0, meas_level=2)
+        braket_circuit = Circuit().h(0)
+        device.run_batch.assert_called_once_with([braket_circuit, braket_circuit], shots=0)
 
-        braket_circuit = Circuit().add_verbatim_box(
+        backend.run([circuit, circuit], shots=0, native=True)
+        native_circuit = Circuit().add_verbatim_box(
             Circuit().rz(0, np.pi / 2).rx(0, np.pi / 2).rz(0, np.pi / 2)
         )
-        device.run_batch.assert_called_with([braket_circuit, braket_circuit], shots=0)
-        device.run_batch.assert_called_once()
+        device.run_batch.assert_called_with([native_circuit, native_circuit], shots=0)
+        self.assertEqual(device.run_batch.call_count, 2)
 
     def test_run_multiple_circuits_program_set(self):
         """Tests run with multiple circuits"""
@@ -241,14 +244,19 @@ def test_run_multiple_circuits_program_set(self):
         circuit.h(0)
 
         backend.run([circuit, circuit], shots=5, meas_level=2)
+        braket_circuit = Circuit().h(0)
+        device.run.assert_called_once_with(
+            ProgramSet([braket_circuit, braket_circuit], shots_per_executable=5)
+        )
 
-        braket_circuit = Circuit().add_verbatim_box(
+        backend.run([circuit, circuit], shots=5, native=True)
+        native_circuit = Circuit().add_verbatim_box(
             Circuit().rz(0, np.pi / 2).rx(0, np.pi / 2).rz(0, np.pi / 2)
         )
         device.run.assert_called_with(
-            ProgramSet([braket_circuit, braket_circuit], shots_per_executable=5)
+            ProgramSet([native_circuit, native_circuit], shots_per_executable=5)
         )
-        device.run.assert_called_once()
+        self.assertEqual(device.run.call_count, 2)
 
     def test_run_invalid_run_input(self):
         """Tests run with invalid input to run"""
@@ -303,7 +311,6 @@ def test_meas_level_1(self):
         with self.assertRaises(exception.QiskitBraketException):
             backend.run(circuit, shots=10, meas_level=1)
 
-    @skip(reason="qiskit-algorithms doesn't support V2 primitives yet")
     def test_vqe(self):
         """Tests VQE."""
         local_simulator = BraketLocalBackend(name="default")

tests/providers/test_braket_provider.py

@@ -186,7 +186,7 @@ def test_discontinous_qubit_indices_qiskit_transpilation(self, mock_get_devices)
         circ.cx(2, 3)
 
         self.assertEqual(
-            to_braket(circ, target=backend.target, braket_qubits=backend._braket_qubits).qubits,
+            to_braket(circ, target=backend.target, qubit_labels=backend.qubit_labels).qubits,
             {0, 1, 2, 7},
         )