fix a misused 2-qubit sample result type

qiskit_braket_provider/providers/adapter.py

@@ -8,7 +8,6 @@
     FreeParameter,
     Instruction,
     gates,
-    result_types,
     observables,
 )
 from braket.device_schema import (
@@ -424,42 +423,40 @@ def convert_qiskit_to_braket_circuit(circuit: QuantumCircuit) -> Circuit:
     if circuit.global_phase > _EPS:
         warnings.warn("Circuit transpilation resulted in global phase shift")
     # handle qiskit to braket conversion
-    for qiskit_gates in circuit.data:
-        name = qiskit_gates[0].name
-        if name == "measure":
-            # TODO: change Probability result type for Sample for proper functioning # pylint:disable=fixme
-            # Getting the index from the bit mapping
-            quantum_circuit.add_result_type(
-                # pylint:disable=fixme
-                result_types.Sample(
-                    observable=observables.Z(),
-                    target=[
-                        circuit.find_bit(qiskit_gates[1][0]).index,
-                        circuit.find_bit(qiskit_gates[2][0]).index,
-                    ],
-                )
+    for circuit_instruction in circuit.data:
+        operation = circuit_instruction.operation
+        gate_name = operation.name
+
+        qubits = circuit_instruction.qubits
+
+        if gate_name == "measure":
+            qubit = qubits[0]  # qubit count = 1 for measure
+            qubit_index = circuit.find_bit(qubit).index
+            quantum_circuit.sample(
+                observable=observables.Z(),
+                target=[
+                    qubit_index,
+                ],
             )
-        elif name == "barrier":
+        elif gate_name == "barrier":
             # This does not exist
             pass
-        elif name == "reset":
+        elif gate_name == "reset":
             raise NotImplementedError(
                 "reset operation not supported by qiskit to braket adapter"
             )
         else:
-            params = []
-            if hasattr(qiskit_gates[0], "params"):
-                params = qiskit_gates[0].params
+            params = operation.params if hasattr(operation, "params") else []
 
             for i, param in enumerate(params):
                 if isinstance(param, Parameter):
                     params[i] = FreeParameter(param.name)
 
-            for gate in qiskit_gate_names_to_braket_gates[name](*params):
+            for gate in qiskit_gate_names_to_braket_gates[gate_name](*params):
                 instruction = Instruction(
                     # Getting the index from the bit mapping
                     operator=gate,
-                    target=[circuit.find_bit(i).index for i in qiskit_gates[1]],
+                    target=[circuit.find_bit(qubit).index for qubit in qubits],
                 )
                 quantum_circuit += instruction
     return quantum_circuit

tests/providers/test_adapter.py

@@ -6,7 +6,7 @@
 
 import numpy as np
 
-from qiskit import QuantumCircuit, execute, BasicAer
+from qiskit import QuantumCircuit, execute, BasicAer, QuantumRegister, ClassicalRegister
 from qiskit.circuit import Parameter
 from qiskit.circuit.library import PauliEvolutionGate
 from qiskit.quantum_info import SparsePauliOp
@@ -305,14 +305,65 @@ def test_sample_result_type(self):
         qiskit_circuit.measure(0, 0)
         braket_circuit = convert_qiskit_to_braket_circuit(qiskit_circuit)
 
-        circuits = (
+        expected_braket_circuit = (
             Circuit()  # pylint: disable=no-member
             .h(0)
             .cnot(0, 1)
             .sample(observable=observables.Z(), target=0)
         )
 
-        self.assertEqual(braket_circuit, circuits)
+        self.assertEqual(braket_circuit, expected_braket_circuit)
+
+    def test_sample_result_type_different_indices(self):
+        """
+        Tests the translation of a measure instruction.
+
+        We test that the issue #132 has been fixed. The qubit index
+        can be different from the classical bit index. The classical bit
+        is ignored during the translation.
+        """
+
+        qiskit_circuit = QuantumCircuit(2, 2)
+        qiskit_circuit.h(0)
+        qiskit_circuit.cnot(0, 1)
+        qiskit_circuit.measure(0, 1)
+        braket_circuit = convert_qiskit_to_braket_circuit(qiskit_circuit)
+
+        expected_braket_circuit = (
+            Circuit()  # pylint: disable=no-member
+            .h(0)
+            .cnot(0, 1)
+            .sample(observable=observables.Z(), target=0)
+        )
+
+        self.assertEqual(braket_circuit, expected_braket_circuit)
+
+    def test_multiple_registers(self):
+        """
+        Tests the use of multiple registers.
+
+        Confirming that #51 has been fixed.
+        """
+        qreg_a = QuantumRegister(2, "qreg_a")
+        qreg_b = QuantumRegister(1, "qreg_b")
+        creg = ClassicalRegister(2, "creg")
+        qiskit_circuit = QuantumCircuit(qreg_a, qreg_b, creg)
+        qiskit_circuit.h(qreg_a[0])
+        qiskit_circuit.cnot(qreg_a[0], qreg_b[0])
+        qiskit_circuit.x(qreg_a[1])
+        qiskit_circuit.measure(qreg_a[0], creg[1])
+        qiskit_circuit.measure(qreg_b[0], creg[0])
+        braket_circuit = convert_qiskit_to_braket_circuit(qiskit_circuit)
+
+        expected_braket_circuit = (
+            Circuit()  # pylint: disable=no-member
+            .h(0)
+            .cnot(0, 2)
+            .x(1)
+            .sample(observable=observables.Z(), target=0)
+            .sample(observable=observables.Z(), target=2)
+        )
+        self.assertEqual(braket_circuit, expected_braket_circuit)
 
 
 class TestVerbatimBoxWrapper(TestCase):