transpile only ansatz with default

Qiskit · May 24, 2021 · f4aec15 · f4aec15
1 parent c795068
commit f4aec15
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Showing 2 changed files with 16 additions and 3 deletions.
diff --git a/qiskit/algorithms/minimum_eigen_solvers/vqe.py b/qiskit/algorithms/minimum_eigen_solvers/vqe.py
@@ -104,6 +104,7 @@ def __init__(
         max_evals_grouped: int = 1,
         callback: Optional[Callable[[int, np.ndarray, float, float], None]] = None,
         quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None,
+        split_transpile: bool = False,
     ) -> None:
         """
 
@@ -139,6 +140,8 @@ def __init__(
                 These are: the evaluation count, the optimizer parameters for the
                 ansatz, the evaluated mean and the evaluated standard deviation.`
             quantum_instance: Quantum Instance or Backend
+            split_transpile: ``True`` allows transpiling circuits for ansatz and expectation
+                separately.
         """
         validate_min("max_evals_grouped", max_evals_grouped, 1)
         if ansatz is None:
@@ -156,6 +159,7 @@ def __init__(
         self._expectation = expectation
         self._user_valid_expectation = self._expectation is not None
         self._include_custom = include_custom
+        self._split_transpile = split_transpile
         self._expect_op = None
 
         super().__init__(
@@ -197,7 +201,8 @@ def quantum_instance(
         super(VQE, self.__class__).quantum_instance.__set__(self, quantum_instance)
 
         self._circuit_sampler = CircuitSampler(
-            self._quantum_instance, param_qobj=is_aer_provider(self._quantum_instance.backend)
+            self._quantum_instance, param_qobj=is_aer_provider(self._quantum_instance.backend),
+            skip_transpile=self._split_transpile
         )
 
     @property
@@ -317,7 +322,10 @@ def construct_expectation(
             )
 
         observable_meas = self.expectation.convert(StateFn(operator, is_measurement=True))
-        ansatz_circuit_op = CircuitStateFn(wave_function)
+        if self._split_transpile:
+            ansatz_circuit_op = CircuitStateFn(self.quantum_instance.transpile(wave_function)[0])
+        else:
+            ansatz_circuit_op = CircuitStateFn(wave_function)
         return observable_meas.compose(ansatz_circuit_op).reduce()
 
     def construct_circuit(

diff --git a/qiskit/opflow/converters/circuit_sampler.py b/qiskit/opflow/converters/circuit_sampler.py
@@ -58,6 +58,7 @@ def __init__(
         param_qobj: bool = False,
         attach_results: bool = False,
         caching: str = "last",
+        skip_transpile: bool = False,
     ) -> None:
         """
         Args:
@@ -97,6 +98,7 @@ def __init__(
         self._transpiled_circ_cache: Optional[List[Any]] = None
         self._transpiled_circ_templates: Optional[List[Any]] = None
         self._transpile_before_bind = True
+        self._skip_transpile = skip_transpile
 
     def _check_quantum_instance_and_modes_consistent(self) -> None:
         """Checks whether the statevector and param_qobj settings are compatible with the
@@ -294,7 +296,10 @@ def sample_circuits(
                 circuits = [op_c.to_circuit(meas=True) for op_c in circuit_sfns]
 
             try:
-                self._transpiled_circ_cache = self.quantum_instance.transpile(circuits)
+                if self._skip_transpile:
+                    self._transpiled_circ_cache = circuits
+                else:
+                    self._transpiled_circ_cache = self.quantum_instance.transpile(circuits)
             except QiskitError:
                 logger.debug(
                     r"CircuitSampler failed to transpile circuits with unbound "