final layout hack

qiskit/opflow/converters/circuit_sampler.py

@@ -31,6 +31,7 @@
 from qiskit.opflow.state_fns.dict_state_fn import DictStateFn
 from qiskit.opflow.state_fns.state_fn import StateFn
 from qiskit.providers import Backend, BaseBackend
+from qiskit.transpiler.layout import Layout
 from qiskit.utils.backend_utils import is_aer_provider, is_statevector_backend
 from qiskit.utils.quantum_instance import QuantumInstance
 
@@ -197,34 +198,41 @@ def convert(
                 ]
 
                 common_circuit = operator[1].to_circuit_op().reduce().to_circuit()
+                len_common_circuit = len(common_circuit)
                 try:
                     # 1. transpile a common circuit
+                    common_circuit.measure_all()
                     transpiled_common_circuit = self.quantum_instance.transpile(common_circuit)[0]
+                    layout = Layout(
+                        {
+                            i: qr[0]
+                            for i, (_, qr, _) in enumerate(
+                                transpiled_common_circuit[-common_circuit.num_qubits :]
+                            )
+                        }
+                    )
+                    transpiled_common_circuit.remove_final_measurements()
 
                     # 2. transpile diff circuits
                     diff_circuits = []
                     for circuit in circuits:
                         diff_circuit = circuit.copy()
-                        del diff_circuit.data[0 : len(common_circuit)]
+                        del diff_circuit.data[0 : len_common_circuit]
                         diff_circuits.append(diff_circuit)
 
-                    if transpiled_common_circuit._layout is not None:
-                        layout = transpiled_common_circuit._layout.copy()
-                        used_qubits = set(
-                            used_qubit
-                            for diff_circuit in diff_circuits
-                            for used_qubit in diff_circuit.qubits
-                        )
-                        for q in list(layout.get_virtual_bits().keys()):
-                            if q not in used_qubits:
-                                del layout[q]
-                        orig_layout = self.quantum_instance.compile_config["initial_layout"]
-                        self.quantum_instance.compile_config["initial_layout"] = layout
+                    used_qubits = set(
+                        used_qubit
+                        for diff_circuit in diff_circuits
+                        for used_qubit in diff_circuit.qubits
+                    )
+                    for q in list(layout.get_virtual_bits().keys()):
+                        if q not in used_qubits:
+                            del layout[q]
+                    orig_layout = self.quantum_instance.compile_config["initial_layout"]
 
+                    self.quantum_instance.compile_config["initial_layout"] = layout
                     diff_circuits = self.quantum_instance.transpile(diff_circuits)
-
-                    if transpiled_common_circuit._layout is not None:
-                        self.quantum_instance.compile_config["initial_layout"] = orig_layout
+                    self.quantum_instance.compile_config["initial_layout"] = orig_layout
 
                     # 3. combine
                     transpiled_circuits = []
@@ -240,6 +248,7 @@ def convert(
                     # 4. set transpiled circuit cache
                     self._transpiled_circ_cache = transpiled_circuits
                     self._transpile_before_bind = True
+
                 except QiskitError:
                     logger.debug(
                         r"CircuitSampler failed to transpile circuits with unbound "
@@ -375,6 +384,7 @@ def sample_circuits(
 
             try:
                 self._transpiled_circ_cache = self.quantum_instance.transpile(circuits)
+
             except QiskitError:
                 logger.debug(
                     r"CircuitSampler failed to transpile circuits with unbound "

test/python/opflow/test_state_op_meas_evals.py

@@ -17,13 +17,29 @@
 
 import unittest
 from test.python.opflow import QiskitOpflowTestCase
-from ddt import ddt, data
-import numpy
 
-from qiskit.circuit import QuantumCircuit, Parameter
-from qiskit.utils import QuantumInstance
-from qiskit.opflow import StateFn, Zero, One, H, X, I, Z, Plus, Minus, CircuitSampler, ListOp
+import numpy
+from ddt import data, ddt
+
+from qiskit import BasicAer
+from qiskit.circuit import Parameter, QuantumCircuit
+from qiskit.circuit.library import RealAmplitudes
+from qiskit.opflow import (
+    CircuitSampler,
+    H,
+    I,
+    ListOp,
+    Minus,
+    One,
+    PauliExpectation,
+    Plus,
+    StateFn,
+    X,
+    Z,
+    Zero,
+)
 from qiskit.opflow.exceptions import OpflowError
+from qiskit.utils import QuantumInstance
 
 
 @ddt
@@ -217,6 +233,38 @@ def test_quantum_instance_with_backend_shots(self):
         res = sampler.convert(~Plus @ Plus).eval()
         self.assertAlmostEqual(res, 1 + 0j, places=2)
 
+    def test_split_transpile(self):
+        """Test split transpile for CircuitSampler"""
+        ansatz = StateFn(RealAmplitudes(num_qubits=3, reps=1, entanglement="linear"))
+        observable = StateFn(X ^ I ^ I, is_measurement=True)
+        expectation = PauliExpectation(False).convert(observable @ ansatz)
+        param_bindings = dict(zip(ansatz.parameters, [1] * len(ansatz.parameters)))
+        sampled = CircuitSampler(
+            QuantumInstance(
+                BasicAer.get_backend("qasm_simulator"),
+                seed_simulator=15,
+                seed_transpiler=15,
+                initial_layout=[0, 1, 2],
+                coupling_map=[[0, 1], [0, 2]],
+            ),
+            attach_results=True,
+            split_transpile=False,
+        ).convert(expectation, param_bindings)
+        counts_expected = sampled[1].execution_results["counts"]
+        sampled = CircuitSampler(
+            QuantumInstance(
+                BasicAer.get_backend("qasm_simulator"),
+                seed_simulator=15,
+                seed_transpiler=15,
+                initial_layout=[0, 1, 2],
+                coupling_map=[[0, 1], [0, 2]],
+            ),
+            attach_results=True,
+            split_transpile=True,
+        ).convert(expectation, param_bindings)
+        counts_target = sampled[1].execution_results["counts"]
+        self.assertDictEqual(counts_target, counts_expected)
+
 
 if __name__ == "__main__":
     unittest.main()