Support Experiments initialized with real backends

The JSON encoder and decoder provided by Qiskit Experiments cannot
properly encode and decode the instances of Experiment initialized with
real backends. To cache and recover the tasks of experiments, we have
to delete the backend entry before encoding the task. The issue below
provides an workaround to add the backend back after decoding.

qiskit-community/qiskit-experiments#1508

qiskit_pulse_control/json.py

@@ -1,4 +1,5 @@
 from collections.abc import Callable
+import collections
 import json
 from typing import Any
 
@@ -21,6 +22,13 @@ def default(self, any_object: Any) -> Any:
         if isinstance(any_object, unified_job.Job):
             return self._encode_job(any_object)
         if isinstance(any_object, unified_job.ExperimentJob):
+            # fix https://github.com/qiskit-community/qiskit-experiments/issues/1508
+            copied_experiment = any_object.experiment.copy()
+            experiment_kwargs = getattr(copied_experiment, '__init_kwargs__',
+                                        collections.OrderedDict())
+            if 'backend' in experiment_kwargs:
+                del experiment_kwargs['backend']
+
             encoded_value = {
                 'jobs': [self._encode_job(job) for job in any_object.jobs],
                 'experiment':

qiskit_pulse_control/unified_job.py

@@ -109,7 +109,6 @@ def experiment_data(self) -> framework.ExperimentData:
             return self._experiment_data
         self._experiment_data = framework.ExperimentData(
             experiment=self.experiment)
-        # TODO: check if the runtime jobs is done
         if all(job.status == providers.JobStatus.DONE for job in self.jobs):
             for job in self.jobs:
                 # .add_data() cannot handle PrimitiveResult. The `job_id`
@@ -124,6 +123,11 @@ def experiment_data(self) -> framework.ExperimentData:
             for job in self.jobs:
                 self._experiment_data.add_jobs(
                     [job.runtime_job for job in self.jobs])
+            if (self._experiment_data.status() ==
+                    framework.ExperimentStatus.DONE):
+                self.experiment.analysis.run(
+                    self._experiment_data, replace_results=True)
+                self.analysis_result = self._experiment_data.analysis_results()
         return self._experiment_data