From 48e0b371e4ce9286fcf71eee8b8f6a26066834e1 Mon Sep 17 00:00:00 2001
From: Christopher Wood <cjwood@us.ibm.com>
Date: Mon, 25 Oct 2021 16:43:31 -0400
Subject: [PATCH 1/7] Add backend property to BaseExperiment

---
 .../framework/base_experiment.py              | 177 +++++++++++-------
 .../framework/experiment_data.py              |  25 ++-
 2 files changed, 123 insertions(+), 79 deletions(-)

diff --git a/qiskit_experiments/framework/base_experiment.py b/qiskit_experiments/framework/base_experiment.py
index 47815f98a3..bbf5ec07ab 100644
--- a/qiskit_experiments/framework/base_experiment.py
+++ b/qiskit_experiments/framework/base_experiment.py
@@ -14,9 +14,9 @@
 """
 
 from abc import ABC, abstractmethod
-from typing import Iterable, Optional, Tuple, List, Dict
 import copy
 from numbers import Integral
+from typing import Sequence, Optional, Tuple, List, Dict, Union
 
 from qiskit import transpile, assemble, QuantumCircuit
 from qiskit.providers import BaseJob
@@ -47,12 +47,18 @@ class BaseExperiment(ABC):
     # ExperimentData class for experiment
     __experiment_data__ = ExperimentData
 
-    def __init__(self, qubits: Iterable[int], experiment_type: Optional[str] = None):
+    def __init__(
+        self,
+        qubits: Sequence[int],
+        backend: Optional[Backend] = None,
+        experiment_type: Optional[str] = None,
+    ):
         """Initialize the experiment object.
 
         Args:
             qubits: the number of qubits or list of physical qubits for
                     the experiment.
+            backend: Optional, the backend to run the experiment on.
             experiment_type: Optional, the experiment type string.
 
         Raises:
@@ -61,6 +67,11 @@ def __init__(self, qubits: Iterable[int], experiment_type: Optional[str] = None)
         # Experiment identification metadata
         self._type = experiment_type if experiment_type else type(self).__name__
 
+        # Backend
+        self._backend = None
+        if backend is not None:
+            self._set_backend(backend)
+
         # Circuit parameters
         if isinstance(qubits, Integral):
             self._num_qubits = qubits
@@ -77,16 +88,65 @@ def __init__(self, qubits: Iterable[int], experiment_type: Optional[str] = None)
         self._run_options = self._default_run_options()
         self._analysis_options = self._default_analysis_options()
 
+    @property
+    def experiment_type(self) -> str:
+        """Return experiment type."""
+        return self._type
+
+    @property
+    def physical_qubits(self) -> Tuple[int]:
+        """Return the device qubits for the experiment."""
+        return self._physical_qubits
+
+    @property
+    def num_qubits(self) -> int:
+        """Return the number of qubits for the experiment."""
+        return self._num_qubits
+
+    @property
+    def backend(self) -> Union[Backend, None]:
+        """Return the backend for the experiment"""
+        return self._backend
+
+    @backend.setter
+    def backend(self, backend: Union[Backend, None]) -> None:
+        """Set the backend for the experiment"""
+        self._set_backend(backend)
+
+    def _set_backend(self, backend: Backend):
+        """Set the backend for the experiment.
+
+        Subclasses can override this method to extract additional
+        properties from the supplied backend if required.
+        """
+        self._backend = backend
+
+        # Scheduling parameters
+        if not self._backend.configuration().simulator and not isinstance(backend, FakeBackend):
+            timing_constraints = getattr(self.transpile_options, "timing_constraints", {})
+            if "acquire_alignment" not in timing_constraints:
+                timing_constraints["aquire_aligment"] = 16
+            scheduling_method = getattr(self.transpile_options, "scheduling_method", "alap")
+            self.set_transpile_options(
+                timing_constraints=timing_constraints, scheduling_method=scheduling_method
+            )
+
+    def copy(self) -> "BaseExperiment":
+        """Return a copy of the experiment"""
+        return copy.copy(self)
+
     def run(
         self,
-        backend: Backend,
+        backend: Optional[Backend] = None,
         analysis: bool = True,
         **run_options,
     ) -> ExperimentData:
         """Run an experiment and perform analysis.
 
         Args:
-            backend: The backend to run the experiment on.
+            backend: Optional, the backend to run the experiment on. This
+                     will override any currently set backends for the single
+                     execution.
             analysis: If True run analysis on the experiment data.
             run_options: backend runtime options used for circuit execution.
 
@@ -97,70 +157,43 @@ def run(
             QiskitError: if experiment is run with an incompatible existing
                          ExperimentData container.
         """
-        # Create experiment data container
-        experiment_data = self._initialize_experiment_data(backend)
+        if backend is None:
+            experiment = self
+        else:
+            experiment = self.copy()
+            experiment._set_backend(backend)
+        if experiment.backend is None:
+            raise QiskitError("Cannot run experiment, no backend has been set.")
+
+        # Initialize result container
+        experiment_data = experiment._initialize_experiment_data()
 
         # Run options
-        run_opts = copy.copy(self.run_options)
+        run_opts = copy.copy(experiment.run_options)
         run_opts.update_options(**run_options)
         run_opts = run_opts.__dict__
 
-        # Scheduling parameters
-        if backend.configuration().simulator is False and isinstance(backend, FakeBackend) is False:
-            timing_constraints = getattr(self.transpile_options.__dict__, "timing_constraints", {})
-            timing_constraints["acquire_alignment"] = getattr(
-                timing_constraints, "acquire_alignment", 16
-            )
-            scheduling_method = getattr(
-                self.transpile_options.__dict__, "scheduling_method", "alap"
-            )
-            self.set_transpile_options(
-                timing_constraints=timing_constraints, scheduling_method=scheduling_method
-            )
-
         # Generate and transpile circuits
-        transpile_opts = copy.copy(self.transpile_options.__dict__)
-        transpile_opts["initial_layout"] = list(self._physical_qubits)
-        circuits = transpile(self.circuits(backend), backend, **transpile_opts)
-        self._postprocess_transpiled_circuits(circuits, backend, **run_options)
-
-        # Run experiment jobs
-        max_experiments = getattr(backend.configuration(), "max_experiments", None)
-        if max_experiments and len(circuits) > max_experiments:
-            # Split jobs for backends that have a maximum job size
-            job_circuits = [
-                circuits[i : i + max_experiments] for i in range(0, len(circuits), max_experiments)
-            ]
-        else:
-            # Run as single job
-            job_circuits = [circuits]
+        transpile_opts = copy.copy(experiment.transpile_options.__dict__)
+        transpile_opts["initial_layout"] = list(experiment.physical_qubits)
+        circuits = transpile(experiment.circuits(), experiment.backend, **transpile_opts)
+        experiment._postprocess_transpiled_circuits(circuits, **run_options)
 
         # Run jobs
-        jobs = []
-        for circs in job_circuits:
-            if isinstance(backend, LegacyBackend):
-                qobj = assemble(circs, backend=backend, **run_opts)
-                job = backend.run(qobj)
-            else:
-                job = backend.run(circs, **run_opts)
-            jobs.append(job)
-
-        # Add experiment option metadata
-        self._add_job_metadata(experiment_data, jobs, **run_opts)
-
-        # Add jobs
+        jobs = experiment._run_jobs(circuits, **run_opts)
         experiment_data.add_data(jobs)
+        experiment._add_job_metadata(experiment_data, jobs, **run_opts)
 
         # Optionally run analysis
-        if analysis and self.__analysis_class__:
+        if analysis and self.__analysis_class__ is not None:
             experiment_data.add_analysis_callback(self.run_analysis)
 
         # Return the ExperimentData future
         return experiment_data
 
-    def _initialize_experiment_data(self, backend: Backend) -> ExperimentData:
+    def _initialize_experiment_data(self) -> ExperimentData:
         """Initialize the return data container for the experiment run"""
-        return self.__experiment_data__(experiment=self, backend=backend)
+        return self.__experiment_data__(experiment=self)
 
     def run_analysis(self, experiment_data: ExperimentData, **options) -> ExperimentData:
         """Run analysis and update ExperimentData with analysis result.
@@ -187,20 +220,29 @@ def run_analysis(self, experiment_data: ExperimentData, **options) -> Experiment
         analysis.run(experiment_data, **analysis_options)
         return experiment_data
 
-    @property
-    def num_qubits(self) -> int:
-        """Return the number of qubits for this experiment."""
-        return self._num_qubits
-
-    @property
-    def physical_qubits(self) -> Tuple[int]:
-        """Return the physical qubits for this experiment."""
-        return self._physical_qubits
+    def _run_jobs(self, circuits: List[QuantumCircuit], **run_options) -> List[BaseJob]:
+        """Run circuits on backend as 1 or more jobs."""
+        # Run experiment jobs
+        max_experiments = getattr(self.backend.configuration(), "max_experiments", None)
+        if max_experiments and len(circuits) > max_experiments:
+            # Split jobs for backends that have a maximum job size
+            job_circuits = [
+                circuits[i : i + max_experiments] for i in range(0, len(circuits), max_experiments)
+            ]
+        else:
+            # Run as single job
+            job_circuits = [circuits]
 
-    @property
-    def experiment_type(self) -> str:
-        """Return experiment type."""
-        return self._type
+        # Run jobs
+        jobs = []
+        for circs in job_circuits:
+            if isinstance(self.backend, LegacyBackend):
+                qobj = assemble(circs, backend=self.backend, **run_options)
+                job = self.backend.run(qobj)
+            else:
+                job = self.backend.run(circs, **run_options)
+            jobs.append(job)
+        return jobs
 
     @classmethod
     def analysis(cls):
@@ -211,12 +253,9 @@ def analysis(cls):
         return cls.__analysis_class__()
 
     @abstractmethod
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Return a list of experiment circuits.
 
-        Args:
-            backend: Optional, a backend object.
-
         Returns:
             A list of :class:`QuantumCircuit`.
 
@@ -330,7 +369,7 @@ def set_analysis_options(self, **fields):
         """
         self._analysis_options.update_options(**fields)
 
-    def _postprocess_transpiled_circuits(self, circuits, backend, **run_options):
+    def _postprocess_transpiled_circuits(self, circuits: List[QuantumCircuit], **run_options):
         """Additional post-processing of transpiled circuits before running on backend"""
         pass
 
diff --git a/qiskit_experiments/framework/experiment_data.py b/qiskit_experiments/framework/experiment_data.py
index eae48238bb..f5a12769fb 100644
--- a/qiskit_experiments/framework/experiment_data.py
+++ b/qiskit_experiments/framework/experiment_data.py
@@ -35,9 +35,15 @@ def __init__(self, experiment=None, backend=None, parent_id=None, job_ids=None):
                 in the setting of a composite experiment
             job_ids (list[str]): Optional, IDs of jobs submitted for the experiment.
         """
+        if experiment is not None:
+            backend = backend or experiment.backend
+            experiment_type = experiment.experiment_type
+        else:
+            experiment_type = None
+
         self._experiment = experiment
         super().__init__(
-            experiment_type=experiment.experiment_type if experiment else None,
+            experiment_type=experiment_type,
             backend=backend,
             parent_id=parent_id,
             job_ids=job_ids,
@@ -46,8 +52,8 @@ def __init__(self, experiment=None, backend=None, parent_id=None, job_ids=None):
 
     @property
     def experiment(self):
-        """Return Experiment object.
-
+        """Return the experiment for this data.
+        
         Returns:
             BaseExperiment: the experiment object.
         """
@@ -98,11 +104,10 @@ def _copy_metadata(self, new_instance: Optional["ExperimentData"] = None) -> "Ex
         return super()._copy_metadata(new_instance)
 
     def __repr__(self):
-        out = f"{type(self).__name__}({self.experiment_type}"
-        out += f", {self.experiment_id}"
-        if self.backend:
-            out += f", backend={self.backend}"
-        if self.job_ids:
-            out += f", job_ids={self.job_ids}"
-        out += ")"
+        out = (
+            f"<ExperimentData[{self.experiment_type}]"
+            f", backend: {self.backend}"
+            f", status: {self.status()}"
+            f", experiment_id: {self.experiment_id}>"
+        )
         return out

From de38c2ebcf9e164b7c57447d2db9c5693946d44d Mon Sep 17 00:00:00 2001
From: Christopher Wood <cjwood@us.ibm.com>
Date: Mon, 25 Oct 2021 17:13:07 -0400
Subject: [PATCH 2/7] Update experiments for API changes

---
 .../example/example_experiment.py             |  2 +-
 .../base_calibration_experiment.py            | 10 +++---
 .../framework/composite/batch_experiment.py   |  4 +--
 .../composite/composite_experiment.py         | 18 ++++++++--
 .../composite/parallel_experiment.py          |  4 +--
 .../library/calibration/drag.py               | 16 ++++-----
 .../library/calibration/fine_amplitude.py     |  6 +++-
 .../library/calibration/fine_drag.py          | 16 ++++-----
 .../library/calibration/rabi.py               | 22 ++++++------
 .../library/calibration/ramsey_xy.py          | 13 ++++---
 .../library/calibration/rough_frequency.py    |  6 +++-
 .../characterization/cr_hamiltonian.py        | 15 ++++----
 .../characterization/fine_amplitude.py        | 13 +++----
 .../characterization/qubit_spectroscopy.py    | 35 +++++++++++--------
 .../library/characterization/t1.py            | 13 ++++---
 .../library/characterization/t2ramsey.py      | 19 +++++-----
 .../library/quantum_volume/qv_experiment.py   | 11 +++---
 .../interleaved_rb_experiment.py              |  5 ++-
 .../randomized_benchmarking/rb_experiment.py  | 14 ++++----
 .../tomography/tomography_experiment.py       |  7 ++--
 test/fake_experiment.py                       |  2 +-
 test/test_framework.py                        |  2 +-
 22 files changed, 138 insertions(+), 115 deletions(-)

diff --git a/docs/_ext/custom_styles/example/example_experiment.py b/docs/_ext/custom_styles/example/example_experiment.py
index 6c42e7e593..75648e86ca 100644
--- a/docs/_ext/custom_styles/example/example_experiment.py
+++ b/docs/_ext/custom_styles/example/example_experiment.py
@@ -212,5 +212,5 @@ def __init__(self, qubit: int):
         """
         super().__init__(qubits=[qubit])
 
-    def circuits(self, backend=None):
+    def circuits(self):
         pass
diff --git a/qiskit_experiments/calibration_management/base_calibration_experiment.py b/qiskit_experiments/calibration_management/base_calibration_experiment.py
index d46506aff6..899f83da58 100644
--- a/qiskit_experiments/calibration_management/base_calibration_experiment.py
+++ b/qiskit_experiments/calibration_management/base_calibration_experiment.py
@@ -339,9 +339,9 @@ def get_schedule(
 
         return schedules
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """A wrapper to introduce an optional hook to add circuit metadata."""
-        circuits = super().circuits(backend)
+        circuits = super().circuits()
 
         self._add_cal_metadata(circuits)
 
@@ -358,14 +358,16 @@ def _add_cal_metadata(self, circuits: List[QuantumCircuit]):
 
     def run(
         self,
-        backend: Backend,
+        backend: Optional[Backend] = None,
         analysis: bool = True,
         **run_options,
     ) -> ExperimentData:
         """Run an experiment, perform analysis, and update any calibrations.
 
         Args:
-            backend: The backend to run the experiment on.
+            backend: Optional, the backend to run the experiment on. This
+                     will override any currently set backends for the single
+                     execution.
             analysis: If True run analysis on the experiment data.
             run_options: backend runtime options used for circuit execution.
 
diff --git a/qiskit_experiments/framework/composite/batch_experiment.py b/qiskit_experiments/framework/composite/batch_experiment.py
index c6d0a71ada..43ab84d0d7 100644
--- a/qiskit_experiments/framework/composite/batch_experiment.py
+++ b/qiskit_experiments/framework/composite/batch_experiment.py
@@ -41,7 +41,7 @@ def __init__(self, experiments):
         qubits = tuple(self._qubit_map.keys())
         super().__init__(experiments, qubits)
 
-    def circuits(self, backend=None):
+    def circuits(self):
 
         batch_circuits = []
 
@@ -51,7 +51,7 @@ def circuits(self, backend=None):
                 qubit_mapping = None
             else:
                 qubit_mapping = [self._qubit_map[qubit] for qubit in expr.physical_qubits]
-            for circuit in expr.circuits(backend):
+            for circuit in expr.circuits():
                 # Update metadata
                 circuit.metadata = {
                     "experiment_type": self._type,
diff --git a/qiskit_experiments/framework/composite/composite_experiment.py b/qiskit_experiments/framework/composite/composite_experiment.py
index 5c41d0e0f2..983ee9ec45 100644
--- a/qiskit_experiments/framework/composite/composite_experiment.py
+++ b/qiskit_experiments/framework/composite/composite_experiment.py
@@ -41,7 +41,7 @@ def __init__(self, experiments, qubits, experiment_type=None):
         super().__init__(qubits, experiment_type=experiment_type)
 
     @abstractmethod
-    def circuits(self, backend=None):
+    def circuits(self):
         pass
 
     @property
@@ -64,6 +64,18 @@ def component_analysis(self, index):
         """Return the component experiment Analysis object"""
         return self.component_experiment(index).analysis()
 
+    def copy(self) -> "BaseExperiment":
+        """Return a copy of the experiment"""
+        ret = super().copy()
+        # Recursively call copy of component experiments
+        ret._experiments = [exp.copy() for exp in self._experiments]
+        return ret
+
+    def _set_backend(self, backend):
+        super()._set_backend(backend)
+        for subexp in self._experiments:
+            subexp._set_backend(backend)
+
     def _add_job_metadata(self, experiment_data, jobs, **run_options):
         # Add composite metadata
         super()._add_job_metadata(experiment_data, jobs, **run_options)
@@ -85,7 +97,7 @@ def _add_job_metadata(self, experiment_data, jobs, **run_options):
             sub_data = experiment_data.component_experiment_data(i)
             sub_exp._add_job_metadata(sub_data, jobs, **run_options)
 
-    def _postprocess_transpiled_circuits(self, circuits, backend, **run_options):
+    def _postprocess_transpiled_circuits(self, circuits, **run_options):
         for expr in self._experiments:
             if not isinstance(expr, CompositeExperiment):
-                expr._postprocess_transpiled_circuits(circuits, backend, **run_options)
+                expr._postprocess_transpiled_circuits(circuits, **run_options)
diff --git a/qiskit_experiments/framework/composite/parallel_experiment.py b/qiskit_experiments/framework/composite/parallel_experiment.py
index 286b6c8efc..b22a1e5382 100644
--- a/qiskit_experiments/framework/composite/parallel_experiment.py
+++ b/qiskit_experiments/framework/composite/parallel_experiment.py
@@ -32,7 +32,7 @@ def __init__(self, experiments):
             qubits += exp.physical_qubits
         super().__init__(experiments, qubits)
 
-    def circuits(self, backend=None):
+    def circuits(self):
 
         sub_circuits = []
         sub_qubits = []
@@ -42,7 +42,7 @@ def circuits(self, backend=None):
         # Generate data for combination
         for expr in self._experiments:
             # Add subcircuits
-            circs = expr.circuits(backend)
+            circs = expr.circuits()
             sub_circuits.append(circs)
             sub_size.append(len(circs))
 
diff --git a/qiskit_experiments/library/calibration/drag.py b/qiskit_experiments/library/calibration/drag.py
index f939abef74..055c4b9e10 100644
--- a/qiskit_experiments/library/calibration/drag.py
+++ b/qiskit_experiments/library/calibration/drag.py
@@ -17,7 +17,7 @@
 
 from qiskit import QuantumCircuit
 from qiskit.circuit import Gate, Parameter
-from qiskit.providers import Backend
+from qiskit.providers.backend import Backend
 import qiskit.pulse as pulse
 
 from qiskit_experiments.framework import BaseExperiment, Options
@@ -132,20 +132,18 @@ def set_experiment_options(self, reps: Optional[List] = None, **fields):
 
         super().set_experiment_options(reps=reps, **fields)
 
-    def __init__(self, qubit: int):
+    def __init__(self, qubit: int, backend: Optional[Backend] = None):
         """
         Args:
             qubit: The qubit for which to run the Drag calibration.
+            backend: Optional, the backend to run the experiment on.
         """
 
-        super().__init__([qubit])
+        super().__init__([qubit], backend=backend)
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Create the circuits for the Drag calibration.
 
-        Args:
-            backend: A backend object.
-
         Returns:
             circuits: The circuits that will run the Drag calibration.
 
@@ -159,7 +157,7 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
 
         if schedule is None:
             beta = Parameter("β")
-            with pulse.build(backend=backend, name="drag") as schedule:
+            with pulse.build(backend=self.backend, name="drag") as schedule:
                 pulse.play(
                     pulse.Drag(
                         duration=self.experiment_options.duration,
@@ -167,7 +165,7 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
                         sigma=self.experiment_options.sigma,
                         beta=beta,
                     ),
-                    pulse.DriveChannel(self._physical_qubits[0]),
+                    pulse.DriveChannel(self.physical_qubits[0]),
                 )
 
         if len(schedule.parameters) != 1:
diff --git a/qiskit_experiments/library/calibration/fine_amplitude.py b/qiskit_experiments/library/calibration/fine_amplitude.py
index 57dc010a44..d2f641a0ec 100644
--- a/qiskit_experiments/library/calibration/fine_amplitude.py
+++ b/qiskit_experiments/library/calibration/fine_amplitude.py
@@ -16,6 +16,7 @@
 import numpy as np
 
 from qiskit.circuit import Gate, QuantumCircuit
+from qiskit.providers.backend import Backend
 
 from qiskit_experiments.calibration_management import (
     BaseCalibrationExperiment,
@@ -43,6 +44,7 @@ def __init__(
         schedule_name: str,
         cal_parameter_name: Optional[str] = "amp",
         auto_update: bool = True,
+        backend: Optional[Backend] = None,
     ):
         """see class :class:`FineAmplitude` for details.
 
@@ -53,6 +55,7 @@ def __init__(
             cal_parameter_name: The name of the parameter in the schedule to update.
             auto_update: Whether or not to automatically update the calibrations. By
                 default this variable is set to True.
+            backend: Optional, the backend to run the experiment on.
 
         """
         super().__init__(
@@ -62,6 +65,7 @@ def __init__(
             schedule_name=schedule_name,
             cal_parameter_name=cal_parameter_name,
             auto_update=auto_update,
+            backend=backend,
         )
 
         self.transpile_options.inst_map = calibrations.default_inst_map
@@ -99,7 +103,7 @@ def _add_cal_metadata(self, circuits: List[QuantumCircuit]):
 
         param_val = self._cals.get_parameter_value(
             self._param_name,
-            self._physical_qubits,
+            self.physical_qubits,
             self._sched_name,
             group=self.experiment_options.group,
         )
diff --git a/qiskit_experiments/library/calibration/fine_drag.py b/qiskit_experiments/library/calibration/fine_drag.py
index d8de4f72df..f8a6b6c82c 100644
--- a/qiskit_experiments/library/calibration/fine_drag.py
+++ b/qiskit_experiments/library/calibration/fine_drag.py
@@ -12,13 +12,13 @@
 
 """Fine DRAG calibration experiment."""
 
-from typing import Optional, List
+from typing import List, Optional
 import numpy as np
 
 from qiskit import QuantumCircuit
 from qiskit.circuit import Gate
 from qiskit.circuit.library import XGate, SXGate
-from qiskit.providers import Backend
+from qiskit.providers.backend import Backend
 
 from qiskit_experiments.framework import BaseExperiment, Options
 from qiskit_experiments.library.calibration.analysis.fine_drag_analysis import (
@@ -165,13 +165,14 @@ def _default_analysis_options(cls) -> Options:
 
         return options
 
-    def __init__(self, qubit: int):
+    def __init__(self, qubit: int, backend: Optional[Backend] = None):
         """Setup a fine amplitude experiment on the given qubit.
 
         Args:
             qubit: The qubit on which to run the fine amplitude calibration experiment.
+            backend: Optional, the backend to run the experiment on.
         """
-        super().__init__([qubit])
+        super().__init__([qubit], backend=backend)
 
     @staticmethod
     def _pre_circuit() -> QuantumCircuit:
@@ -185,12 +186,9 @@ def _post_circuit() -> QuantumCircuit:
         circ.ry(np.pi / 2, 0)  # Maps unwanted Z rotations to qubit population.
         return circ
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Create the circuits for the fine DRAG calibration experiment.
 
-        Args:
-            backend: A backend object.
-
         Returns:
             A list of circuits with a variable number of gates. Each gate has the same
             pulse schedule.
@@ -216,7 +214,7 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
             circuit.measure_all()
 
             if schedule is not None:
-                circuit.add_calibration(schedule.name, self._physical_qubits, schedule, params=[])
+                circuit.add_calibration(schedule.name, self.physical_qubits, schedule, params=[])
 
             circuit.metadata = {
                 "experiment_type": self._type,
diff --git a/qiskit_experiments/library/calibration/rabi.py b/qiskit_experiments/library/calibration/rabi.py
index a85998ae1c..fcb97b7aea 100644
--- a/qiskit_experiments/library/calibration/rabi.py
+++ b/qiskit_experiments/library/calibration/rabi.py
@@ -104,7 +104,7 @@ def _default_analysis_options(cls) -> Options:
 
         return options
 
-    def __init__(self, qubit: int):
+    def __init__(self, qubit: int, backend: Optional[Backend] = None):
         """Initialize a Rabi experiment on the given qubit.
 
         The parameters of the Gaussian Rabi pulse can be specified at run-time.
@@ -116,8 +116,9 @@ def __init__(self, qubit: int):
 
         Args:
             qubit: The qubit on which to run the Rabi experiment.
+            backend: Optional, the backend to run the experiment on.
         """
-        super().__init__([qubit])
+        super().__init__([qubit], backend=backend)
 
     def _template_circuit(self, amp_param) -> QuantumCircuit:
         """Return the template quantum circuit."""
@@ -144,12 +145,9 @@ def _default_gate_schedule(self, backend: Optional[Backend] = None):
 
         return default_schedule
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Create the circuits for the Rabi experiment.
 
-        Args:
-            backend: A backend object.
-
         Returns:
             A list of circuits with a rabi gate with an attached schedule. Each schedule
             will have a different value of the scanned amplitude.
@@ -163,7 +161,7 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
         schedule = self.experiment_options.get("schedule", None)
 
         if schedule is None:
-            schedule = self._default_gate_schedule(backend=backend)
+            schedule = self._default_gate_schedule(backend=self.backend)
         else:
             if self.physical_qubits[0] not in set(ch.index for ch in schedule.channels):
                 raise CalibrationError(
@@ -182,6 +180,12 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
             self.__rabi_gate_name__, (self.physical_qubits[0],), schedule, params=[param]
         )
 
+        # Get backend dt
+        if self.backend is not None:
+            backend_dt = getattr(self.backend.configuration(), "dt", "n.a.")
+        else:
+            backend_dt = "n.a"
+
         # Create the circuits to run
         circs = []
         for amp in self.experiment_options.amplitudes:
@@ -194,11 +198,9 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
                 "unit": "arb. unit",
                 "amplitude": amp,
                 "schedule": str(schedule),
+                "dt": backend_dt,
             }
 
-            if backend:
-                assigned_circ.metadata["dt"] = getattr(backend.configuration(), "dt", "n.a.")
-
             circs.append(assigned_circ)
 
         return circs
diff --git a/qiskit_experiments/library/calibration/ramsey_xy.py b/qiskit_experiments/library/calibration/ramsey_xy.py
index 7fa7d5d5ec..7f9edb3376 100644
--- a/qiskit_experiments/library/calibration/ramsey_xy.py
+++ b/qiskit_experiments/library/calibration/ramsey_xy.py
@@ -17,8 +17,8 @@
 
 from qiskit import QuantumCircuit
 from qiskit.circuit import Parameter
-from qiskit.providers import Backend
 from qiskit.utils import apply_prefix
+from qiskit.providers.backend import Backend
 
 from qiskit_experiments.framework import BaseExperiment
 from qiskit_experiments.library.calibration.analysis.remsey_xy_analysis import RamseyXYAnalysis
@@ -109,6 +109,7 @@ def __init__(
         delays: Optional[List] = None,
         unit: str = "s",
         osc_freq: float = 2e6,
+        backend: Optional[Backend] = None,
     ):
         """Create new experiment.
 
@@ -118,8 +119,9 @@ def __init__(
             unit: The unit of the delays.
             osc_freq: the oscillation frequency induced by the user through a virtual
                 Rz rotation. This quantity is given in Hz.
+            backend: Optional, the backend to run the experiment on.
         """
-        super().__init__([qubit])
+        super().__init__([qubit], backend=backend)
 
         delays = delays or self.experiment_options.delays
         self.set_experiment_options(delays=delays, unit=unit, osc_freq=osc_freq)
@@ -132,12 +134,9 @@ def _pre_circuit(self) -> QuantumCircuit:
         """
         return QuantumCircuit(1)
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Create the circuits for the Ramsey XY calibration experiment.
 
-        Args:
-            backend: A backend object.
-
         Returns:
             A list of circuits with a variable delay.
 
@@ -149,7 +148,7 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
         conversion_factor = 1
         if self.experiment_options.unit == "dt":
             try:
-                conversion_factor = getattr(backend.configuration(), "dt")
+                conversion_factor = getattr(self.backend.configuration(), "dt")
             except AttributeError as no_dt:
                 raise AttributeError(
                     "Dt parameter is missing from the backend's configuration."
diff --git a/qiskit_experiments/library/calibration/rough_frequency.py b/qiskit_experiments/library/calibration/rough_frequency.py
index 5088ba0c7f..4cb720ac10 100644
--- a/qiskit_experiments/library/calibration/rough_frequency.py
+++ b/qiskit_experiments/library/calibration/rough_frequency.py
@@ -12,7 +12,8 @@
 
 """Calibration version of spectroscopy experiments."""
 
-from typing import Iterable
+from typing import Iterable, Optional
+from qiskit.providers.backend import Backend
 
 from qiskit_experiments.library.characterization.qubit_spectroscopy import QubitSpectroscopy
 from qiskit_experiments.library.characterization.ef_spectroscopy import EFSpectroscopy
@@ -34,6 +35,7 @@ def __init__(
         unit: str = "Hz",
         auto_update: bool = True,
         absolute: bool = True,
+        backend: Optional[Backend] = None,
     ):
         """See :class:`QubitSpectroscopy` for detailed documentation.
 
@@ -48,6 +50,7 @@ def __init__(
                 automatically update the frequency in the calibrations.
             absolute: Boolean to specify if the frequencies are absolute or relative to the
                 qubit frequency in the backend.
+            backend: Optional, the backend to run the experiment on.
 
         Raises:
             QiskitError: if there are less than three frequency shifts or if the unit is not known.
@@ -61,6 +64,7 @@ def __init__(
             absolute,
             updater=Frequency,
             auto_update=auto_update,
+            backend=backend,
         )
 
 
diff --git a/qiskit_experiments/library/characterization/cr_hamiltonian.py b/qiskit_experiments/library/characterization/cr_hamiltonian.py
index 9d44ac925d..ad62bb1e45 100644
--- a/qiskit_experiments/library/characterization/cr_hamiltonian.py
+++ b/qiskit_experiments/library/characterization/cr_hamiltonian.py
@@ -13,7 +13,7 @@
 Cross resonance Hamiltonian tomography.
 """
 
-from typing import List, Tuple, Optional, Iterable, Dict
+from typing import List, Tuple, Iterable, Dict, Optional
 
 import numpy as np
 from qiskit import pulse, circuit, QuantumCircuit
@@ -131,6 +131,7 @@ def __init__(
         qubits: Tuple[int, int],
         flat_top_widths: Iterable[float],
         unit: str = "dt",
+        backend: Optional[Backend] = None,
         **kwargs,
     ):
         """Create a new experiment.
@@ -142,12 +143,13 @@ def __init__(
                 to scan. The total pulse duration including Gaussian rising and falling edges
                 is implicitly computed with experiment parameters ``sigma`` and ``risefall``.
             unit: The time unit of durations.
+            backend: Optional, the backend to run the experiment on.
             kwargs: Pulse parameters. See :meth:`experiment_options` for details.
 
         Raises:
             QiskitError: When ``qubits`` length is not 2.
         """
-        super().__init__(qubits=qubits)
+        super().__init__(qubits, backend=backend)
 
         if len(qubits) != 2:
             raise QiskitError(
@@ -252,12 +254,9 @@ def _build_cr_schedule(
 
         return cross_resonance
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Return a list of experiment circuits.
 
-        Args:
-            backend: The target backend.
-
         Returns:
             A list of :class:`QuantumCircuit`.
 
@@ -268,7 +267,7 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
         prefactor = 1.0
 
         try:
-            dt_factor = backend.configuration().dt
+            dt_factor = self.backend.configuration().dt
         except AttributeError as ex:
             raise AttributeError("Backend configuration does not provide time resolution.") from ex
 
@@ -331,7 +330,7 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
                         gate=cr_gate,
                         qubits=self.physical_qubits,
                         schedule=self._build_cr_schedule(
-                            backend=backend,
+                            backend=self.backend,
                             flat_top_width=prefactor * flat_top_width / self.__n_cr_pulses__,
                             sigma=prefactor * opt.sigma,
                         ),
diff --git a/qiskit_experiments/library/characterization/fine_amplitude.py b/qiskit_experiments/library/characterization/fine_amplitude.py
index 6f42b02762..fadc9862df 100644
--- a/qiskit_experiments/library/characterization/fine_amplitude.py
+++ b/qiskit_experiments/library/characterization/fine_amplitude.py
@@ -18,8 +18,7 @@
 from qiskit import QuantumCircuit
 from qiskit.circuit import Gate
 from qiskit.circuit.library import XGate, SXGate
-from qiskit.providers import Backend
-
+from qiskit.providers.backend import Backend
 from qiskit_experiments.framework import BaseExperiment, Options
 from qiskit_experiments.library.calibration.analysis.fine_amplitude_analysis import (
     FineAmplitudeAnalysis,
@@ -126,14 +125,15 @@ def _default_analysis_options(cls) -> Options:
 
         return options
 
-    def __init__(self, qubit: int, gate: Gate):
+    def __init__(self, qubit: int, gate: Gate, backend: Optional[Backend] = None):
         """Setup a fine amplitude experiment on the given qubit.
 
         Args:
             qubit: The qubit on which to run the fine amplitude calibration experiment.
             gate: The gate that will be repeated.
+            backend: Optional, the backend to run the experiment on.
         """
-        super().__init__([qubit])
+        super().__init__([qubit], backend=backend)
         self.experiment_options.gate = gate
 
     def _pre_circuit(self) -> QuantumCircuit:
@@ -149,12 +149,9 @@ def _pre_circuit(self) -> QuantumCircuit:
 
         return circuit
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Create the circuits for the fine amplitude calibration experiment.
 
-        Args:
-            backend: A backend object.
-
         Returns:
             A list of circuits with a variable number of gates.
 
diff --git a/qiskit_experiments/library/characterization/qubit_spectroscopy.py b/qiskit_experiments/library/characterization/qubit_spectroscopy.py
index d44b3038d3..f0dbeffbbc 100644
--- a/qiskit_experiments/library/characterization/qubit_spectroscopy.py
+++ b/qiskit_experiments/library/characterization/qubit_spectroscopy.py
@@ -97,6 +97,7 @@ def __init__(
         frequencies: Iterable[float],
         unit: str = "Hz",
         absolute: bool = True,
+        backend: Optional[Backend] = None,
     ):
         """
         A spectroscopy experiment run by setting the frequency of the qubit drive.
@@ -114,12 +115,13 @@ def __init__(
                 'MHz', 'GHz'. Internally, all frequencies will be converted to 'Hz'.
             absolute: Boolean to specify if the frequencies are absolute or relative to the
                 qubit frequency in the backend.
+            backend: Optional, the backend to run the experiment on.
 
         Raises:
             QiskitError: if there are less than three frequency shifts or if the unit is not known.
 
         """
-        super().__init__([qubit])
+        super().__init__([qubit], backend=backend)
 
         if len(frequencies) < 3:
             raise QiskitError("Spectroscopy requires at least three frequencies.")
@@ -166,15 +168,12 @@ def _template_circuit(self, freq_param) -> QuantumCircuit:
 
         return circuit
 
-    def circuits(self, backend: Optional[Backend] = None):
+    def circuits(self):
         """Create the circuit for the spectroscopy experiment.
 
         The circuits are based on a GaussianSquare pulse and a frequency_shift instruction
         encapsulated in a gate.
 
-        Args:
-            backend: A backend object.
-
         Returns:
             circuits: The circuits that will run the spectroscopy experiment.
 
@@ -182,24 +181,34 @@ def circuits(self, backend: Optional[Backend] = None):
             QiskitError:
                 - If absolute frequencies are used but no backend is given.
                 - If the backend configuration does not define dt.
+            AttributeError: If backend to run on does not contain 'dt' configuration.
         """
-        if backend is None and self._absolute:
+        if self.backend is None and self._absolute:
             raise QiskitError("Cannot run spectroscopy absolute to qubit without a backend.")
 
         # Create a template circuit
-        sched, freq_param = self._spec_gate_schedule(backend)
+        sched, freq_param = self._spec_gate_schedule(self.backend)
         circuit = self._template_circuit(freq_param)
         circuit.add_calibration("Spec", (self.physical_qubits[0],), sched, params=[freq_param])
 
+        # Get dt
+        try:
+            dt_factor = getattr(self.backend.configuration(), "dt")
+        except AttributeError as no_dt:
+            raise AttributeError("dt parameter is missing in backend configuration") from no_dt
+
+        # Get center frequency from backend
+        if self._absolute:
+            center_freq = self.backend.defaults().qubit_freq_est[self.physical_qubits[0]]
+        else:
+            center_freq = None
+
         # Create the circuits to run
         circs = []
         for freq in self._frequencies:
-
             freq_shift = freq
             if self._absolute:
-                center_freq = backend.defaults().qubit_freq_est[self.physical_qubits[0]]
                 freq_shift -= center_freq
-
             freq_shift = np.round(freq_shift, decimals=3)
 
             assigned_circ = circuit.assign_parameters({freq_param: freq_shift}, inplace=False)
@@ -213,13 +222,9 @@ def circuits(self, backend: Optional[Backend] = None):
                 "sigma": self.experiment_options.sigma,
                 "width": self.experiment_options.width,
                 "schedule": str(sched),
+                "dt": dt_factor,
             }
 
-            try:
-                assigned_circ.metadata["dt"] = getattr(backend.configuration(), "dt")
-            except AttributeError as no_dt:
-                raise QiskitError("Dt parameter is missing in backend configuration") from no_dt
-
             circs.append(assigned_circ)
 
         return circs
diff --git a/qiskit_experiments/library/characterization/t1.py b/qiskit_experiments/library/characterization/t1.py
index d03b9761c1..55361a9e4c 100644
--- a/qiskit_experiments/library/characterization/t1.py
+++ b/qiskit_experiments/library/characterization/t1.py
@@ -16,8 +16,8 @@
 from typing import List, Optional, Union
 import numpy as np
 
-from qiskit.providers import Backend
 from qiskit.circuit import QuantumCircuit
+from qiskit.providers.backend import Backend
 
 from qiskit_experiments.framework import BaseExperiment, Options
 from qiskit_experiments.library.characterization.t1_analysis import T1Analysis
@@ -67,6 +67,7 @@ def __init__(
         qubit: int,
         delays: Union[List[float], np.array],
         unit: Optional[str] = "s",
+        backend: Optional[Backend] = None,
     ):
         """
         Initialize the T1 experiment class
@@ -76,6 +77,7 @@ def __init__(
             delays: delay times of the experiments
             unit: Optional, unit of the delay times. Supported units:
                   's', 'ms', 'us', 'ns', 'ps', 'dt'.
+            backend: Optional, the backend to run the experiment on.
 
         Raises:
             ValueError: if the number of delays is smaller than 3
@@ -84,18 +86,15 @@ def __init__(
             raise ValueError("T1 experiment: number of delays must be at least 3")
 
         # Initialize base experiment
-        super().__init__([qubit])
+        super().__init__([qubit], backend=backend)
 
         # Set experiment options
         self.set_experiment_options(delays=delays, unit=unit)
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """
         Return a list of experiment circuits
 
-        Args:
-            backend: Optional, a backend object
-
         Returns:
             The experiment circuits
 
@@ -104,7 +103,7 @@ def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
         """
         if self.experiment_options.unit == "dt":
             try:
-                dt_factor = getattr(backend.configuration(), "dt")
+                dt_factor = getattr(self.backend.configuration(), "dt")
             except AttributeError as no_dt:
                 raise AttributeError("Dt parameter is missing in backend configuration") from no_dt
 
diff --git a/qiskit_experiments/library/characterization/t2ramsey.py b/qiskit_experiments/library/characterization/t2ramsey.py
index abb93d486f..8dc2a3c31c 100644
--- a/qiskit_experiments/library/characterization/t2ramsey.py
+++ b/qiskit_experiments/library/characterization/t2ramsey.py
@@ -14,13 +14,14 @@
 
 """
 
-from typing import List, Optional, Union
+from typing import List, Union, Optional
 import numpy as np
 
 import qiskit
 from qiskit.utils import apply_prefix
-from qiskit.providers import Backend
 from qiskit.circuit import QuantumCircuit
+from qiskit.providers.backend import Backend
+
 from qiskit_experiments.framework import BaseExperiment, Options
 from .t2ramsey_analysis import T2RamseyAnalysis
 
@@ -82,6 +83,7 @@ def __init__(
         delays: Union[List[float], np.array],
         unit: str = "s",
         osc_freq: float = 0.0,
+        backend: Optional[Backend] = None,
     ):
         """
         **T2Ramsey class**
@@ -96,31 +98,30 @@ def __init__(
                 used for both T2Ramsey and for the frequency.
             osc_freq: the oscillation frequency induced by the user. \
             The frequency is given in Hz.
+            backend: Optional, the backend to run the experiment on.
 
         """
 
-        super().__init__([qubit])
+        super().__init__([qubit], backend=backend)
         self.set_experiment_options(delays=delays, unit=unit, osc_freq=osc_freq)
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Return a list of experiment circuits.
 
         Each circuit consists of a Hadamard gate, followed by a fixed delay,
         a phase gate (with a linear phase), and an additional Hadamard gate.
 
-        Args:
-            backend: Optional, a backend object
-
         Returns:
             The experiment circuits
 
         Raises:
-            AttributeError: if unit is 'dt', but 'dt' parameter is missing in the backend configuration.
+            AttributeError: if unit is 'dt', but 'dt' parameter is missing in
+                            the backend configuration.
         """
         conversion_factor = 1
         if self.experiment_options.unit == "dt":
             try:
-                dt_factor = getattr(backend._configuration, "dt")
+                dt_factor = getattr(self.backend._configuration, "dt")
                 conversion_factor = dt_factor
             except AttributeError as no_dt:
                 raise AttributeError("Dt parameter is missing in backend configuration") from no_dt
diff --git a/qiskit_experiments/library/quantum_volume/qv_experiment.py b/qiskit_experiments/library/quantum_volume/qv_experiment.py
index acfea48c74..f8920afc8c 100644
--- a/qiskit_experiments/library/quantum_volume/qv_experiment.py
+++ b/qiskit_experiments/library/quantum_volume/qv_experiment.py
@@ -15,7 +15,6 @@
 
 from typing import Union, Iterable, Optional, List
 from numpy.random import Generator, default_rng
-from qiskit.providers.backend import Backend
 
 try:
     from qiskit import Aer
@@ -27,6 +26,7 @@
 from qiskit import QuantumCircuit
 from qiskit.circuit.library import QuantumVolume as QuantumVolumeCircuit
 from qiskit import transpile
+from qiskit.providers.backend import Backend
 from qiskit_experiments.framework import BaseExperiment, Options
 from .qv_analysis import QuantumVolumeAnalysis
 
@@ -75,6 +75,7 @@ def __init__(
         qubits: Union[int, Iterable[int]],
         trials: Optional[int] = 100,
         seed: Optional[Union[int, Generator]] = None,
+        backend: Optional[Backend] = None,
         simulation_backend: Optional[Backend] = None,
     ):
         """Initialize a quantum volume experiment.
@@ -85,13 +86,14 @@ def __init__(
             trials: The number of trials to run the quantum volume circuit.
             seed: Seed or generator object for random number
                   generation. If None default_rng will be used.
+            backend: Optional, the backend to run the experiment on.
             simulation_backend: The simulator backend to use to generate
                 the expected results. the simulator must have a 'save_probabilities'
                 method. If None :class:`AerSimulator` simulator will be used
                 (in case :class:`AerSimulator` is not
                 installed :class:`qiskit.quantum_info.Statevector` will be used).
         """
-        super().__init__(qubits)
+        super().__init__(qubits, backend=backend)
 
         # Set configurable options
         self.set_experiment_options(trials=trials)
@@ -150,12 +152,9 @@ def _get_ideal_data(self, circuit: QuantumCircuit, **run_options) -> List[float]
             probabilities = state_vector.probabilities()
         return probabilities
 
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Return a list of Quantum Volume circuits.
 
-        Args:
-            backend (Backend): Optional, a backend object.
-
         Returns:
             A list of :class:`QuantumCircuit`.
         """
diff --git a/qiskit_experiments/library/randomized_benchmarking/interleaved_rb_experiment.py b/qiskit_experiments/library/randomized_benchmarking/interleaved_rb_experiment.py
index 5b593254da..e24cca0fd7 100644
--- a/qiskit_experiments/library/randomized_benchmarking/interleaved_rb_experiment.py
+++ b/qiskit_experiments/library/randomized_benchmarking/interleaved_rb_experiment.py
@@ -20,6 +20,7 @@
 from qiskit.circuit import Instruction
 from qiskit.quantum_info import Clifford
 from qiskit.exceptions import QiskitError
+from qiskit.providers.backend import Backend
 
 from .rb_experiment import StandardRB
 from .interleaved_rb_analysis import InterleavedRBAnalysis
@@ -54,6 +55,7 @@ def __init__(
         num_samples: int = 3,
         seed: Optional[Union[int, Generator]] = None,
         full_sampling: bool = False,
+        backend: Optional[Backend] = None,
     ):
         """Initialize an interleaved randomized benchmarking experiment.
 
@@ -71,9 +73,10 @@ def __init__(
                            all lengths. If False for sample of lengths longer
                            sequences are constructed by appending additional
                            Clifford samples to shorter sequences.
+            backend: The backend to run the experiment on.
         """
         self._set_interleaved_element(interleaved_element)
-        super().__init__(qubits, lengths, num_samples, seed, full_sampling)
+        super().__init__(qubits, lengths, num_samples, seed, full_sampling, backend=backend)
 
     def _sample_circuits(self, lengths, seed=None):
         circuits = []
diff --git a/qiskit_experiments/library/randomized_benchmarking/rb_experiment.py b/qiskit_experiments/library/randomized_benchmarking/rb_experiment.py
index f0c33c2db8..ad004a09b2 100644
--- a/qiskit_experiments/library/randomized_benchmarking/rb_experiment.py
+++ b/qiskit_experiments/library/randomized_benchmarking/rb_experiment.py
@@ -18,9 +18,9 @@
 from numpy.random import Generator, default_rng
 
 from qiskit import QuantumCircuit, QiskitError
-from qiskit.providers import Backend
 from qiskit.quantum_info import Clifford
 from qiskit.circuit import Gate
+from qiskit.providers.backend import Backend
 
 import qiskit_experiments.data_processing as dp
 from qiskit_experiments.framework import BaseExperiment, ParallelExperiment, Options
@@ -66,6 +66,7 @@ def __init__(
         num_samples: int = 3,
         seed: Optional[Union[int, Generator]] = None,
         full_sampling: Optional[bool] = False,
+        backend: Optional[Backend] = None,
     ):
         """Initialize a standard randomized benchmarking experiment.
 
@@ -81,9 +82,10 @@ def __init__(
                            sequences are constructed by appending additional
                            Clifford samples to shorter sequences.
                            The default is False.
+            backend: The backend to run the experiment on.
         """
         # Initialize base experiment
-        super().__init__(qubits)
+        super().__init__(qubits, backend=backend)
         self._verify_parameters(lengths, num_samples)
 
         # Set configurable options
@@ -133,13 +135,9 @@ def _default_experiment_options(cls) -> Options:
 
         return options
 
-    # pylint: disable = arguments-differ
-    def circuits(self, backend: Optional[Backend] = None) -> List[QuantumCircuit]:
+    def circuits(self) -> List[QuantumCircuit]:
         """Return a list of RB circuits.
 
-        Args:
-            backend (Backend): Optional, a backend object.
-
         Returns:
             A list of :class:`QuantumCircuit`.
         """
@@ -231,7 +229,7 @@ def _get_circuit_metadata(self, circuit):
                     return meta
         return None
 
-    def _postprocess_transpiled_circuits(self, circuits, backend, **run_options):
+    def _postprocess_transpiled_circuits(self, circuits, **run_options):
         """Additional post-processing of transpiled circuits before running on backend"""
         for c in circuits:
             meta = self._get_circuit_metadata(c)
diff --git a/qiskit_experiments/library/tomography/tomography_experiment.py b/qiskit_experiments/library/tomography/tomography_experiment.py
index ee79475f85..68e6f15afd 100644
--- a/qiskit_experiments/library/tomography/tomography_experiment.py
+++ b/qiskit_experiments/library/tomography/tomography_experiment.py
@@ -19,6 +19,7 @@
 import numpy as np
 from qiskit.circuit import QuantumCircuit, Instruction
 from qiskit.circuit.library import Permutation
+from qiskit.providers.backend import Backend
 from qiskit.quantum_info.operators.base_operator import BaseOperator
 import qiskit.quantum_info as qi
 from qiskit_experiments.exceptions import QiskitError
@@ -59,6 +60,7 @@ def __init__(
         preparation_qubits: Optional[Iterable[int]] = None,
         basis_indices: Optional[Iterable[Tuple[List[int], List[int]]]] = None,
         qubits: Optional[Iterable[int]] = None,
+        backend: Optional[Backend] = None,
     ):
         """Initialize a tomography experiment.
 
@@ -74,6 +76,7 @@ def __init__(
             basis_indices: Optional, the basis elements to be measured. If None
                 All basis elements will be measured.
             qubits: Optional, the physical qubits for the initial state circuit.
+            backend: The backend to run the experiment on.
 
         Raises:
             QiskitError: if input params are invalid.
@@ -81,7 +84,7 @@ def __init__(
         # Initialize BaseExperiment
         if qubits is None:
             qubits = circuit.num_qubits
-        super().__init__(qubits)
+        super().__init__(qubits, backend=backend)
 
         # Get the target tomography circuit
         if isinstance(circuit, QuantumCircuit):
@@ -150,7 +153,7 @@ def _metadata(self):
             metadata["target"] = copy.copy(self._target)
         return metadata
 
-    def circuits(self, backend=None):
+    def circuits(self):
 
         # Get qubits and clbits
         meas_qubits = self._meas_qubits or range(self.num_qubits)
diff --git a/test/fake_experiment.py b/test/fake_experiment.py
index be11cbb244..f5abddba5a 100644
--- a/test/fake_experiment.py
+++ b/test/fake_experiment.py
@@ -37,6 +37,6 @@ def __init__(self, qubits=1):
         """Initialise the fake experiment."""
         super().__init__(qubits)
 
-    def circuits(self, backend=None):
+    def circuits(self):
         """Fake circuits."""
         return []
diff --git a/test/test_framework.py b/test/test_framework.py
index 99c220b7f1..389b3a4eb6 100644
--- a/test/test_framework.py
+++ b/test/test_framework.py
@@ -35,7 +35,7 @@ def test_job_splitting(self, max_experiments):
         class Experiment(FakeExperiment):
             """Fake Experiment to test job splitting"""
 
-            def circuits(self, backend=None):
+            def circuits(self):
                 """Generate fake circuits"""
                 qc = QuantumCircuit(1)
                 qc.measure_all()

From 046117e2a033fe4cdbaa7cd0b0a88c29c0d5f8fc Mon Sep 17 00:00:00 2001
From: Christopher Wood <cjwood@us.ibm.com>
Date: Mon, 25 Oct 2021 17:35:11 -0400
Subject: [PATCH 3/7] Update tests

---
 test/calibration/experiments/test_drag.py      |  3 ++-
 test/calibration/experiments/test_fine_drag.py |  4 ++--
 test/calibration/experiments/test_rabi.py      |  9 ++++++---
 test/test_cross_resonance_hamiltonian.py       | 10 ++++------
 test/test_qubit_spectroscopy.py                |  3 ++-
 5 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/test/calibration/experiments/test_drag.py b/test/calibration/experiments/test_drag.py
index 4e182f9f8a..48d79d9126 100644
--- a/test/calibration/experiments/test_drag.py
+++ b/test/calibration/experiments/test_drag.py
@@ -109,7 +109,8 @@ def test_default_circuits(self):
 
         drag = DragCal(0)
         drag.set_experiment_options(reps=[2, 4, 8], schedule=self.x_plus)
-        circuits = drag.circuits(DragBackend(gate_name="xp"))
+        drag.backend = DragBackend(gate_name="xp")
+        circuits = drag.circuits()
 
         for idx, expected in enumerate([4, 8, 16]):
             ops = transpile(circuits[idx * 51], backend).count_ops()
diff --git a/test/calibration/experiments/test_fine_drag.py b/test/calibration/experiments/test_fine_drag.py
index 5eb7aa0ae6..f53f5f7f59 100644
--- a/test/calibration/experiments/test_fine_drag.py
+++ b/test/calibration/experiments/test_fine_drag.py
@@ -50,8 +50,8 @@ def test_circuits(self):
 
         drag = FineDrag(0)
         drag.set_experiment_options(schedule=self.schedule)
-
-        for circuit in drag.circuits(FakeArmonk())[1:]:
+        drag.backend = FakeArmonk()
+        for circuit in drag.circuits()[1:]:
             for idx, name in enumerate(["Drag", "rz", "Drag", "rz"]):
                 self.assertEqual(circuit.data[idx][0].name, name)
 
diff --git a/test/calibration/experiments/test_rabi.py b/test/calibration/experiments/test_rabi.py
index 0e1d6ad51e..da7bca0be0 100644
--- a/test/calibration/experiments/test_rabi.py
+++ b/test/calibration/experiments/test_rabi.py
@@ -141,7 +141,8 @@ def test_ef_rabi_circuit(self):
         anharm = -330e6
         rabi12 = EFRabi(2)
         rabi12.set_experiment_options(amplitudes=[0.5], frequency_shift=anharm)
-        circ = rabi12.circuits(RabiBackend())[0]
+        rabi12.backend = RabiBackend()
+        circ = rabi12.circuits()[0]
 
         with pulse.build() as expected:
             pulse.shift_frequency(anharm, pulse.DriveChannel(2))
@@ -161,7 +162,8 @@ def test_default_schedule(self):
 
         rabi = Rabi(2)
         rabi.set_experiment_options(amplitudes=[0.5])
-        circs = rabi.circuits(RabiBackend())
+        rabi.backend = RabiBackend()
+        circs = rabi.circuits()
 
         with pulse.build() as expected:
             pulse.play(pulse.Gaussian(160, 0.5, 40), pulse.DriveChannel(2))
@@ -179,7 +181,8 @@ def test_user_schedule(self):
 
         rabi = Rabi(2)
         rabi.set_experiment_options(schedule=my_schedule, amplitudes=[0.5])
-        circs = rabi.circuits(RabiBackend())
+        rabi.backend = RabiBackend()
+        circs = rabi.circuits()
 
         assigned_sched = my_schedule.assign_parameters({amp: 0.5}, inplace=False)
         self.assertEqual(circs[0].calibrations["Rabi"][((2,), (0.5,))], assigned_sched)
diff --git a/test/test_cross_resonance_hamiltonian.py b/test/test_cross_resonance_hamiltonian.py
index a384d06543..c93d52bf25 100644
--- a/test/test_cross_resonance_hamiltonian.py
+++ b/test/test_cross_resonance_hamiltonian.py
@@ -160,8 +160,6 @@ class TestCrossResonanceHamiltonian(QiskitTestCase):
     def test_circuit_generation(self):
         """Test generated circuits."""
 
-        backend = CrossResonanceHamiltonianBackend()
-
         expr = cr_hamiltonian.CrossResonanceHamiltonian(
             qubits=(0, 1),
             flat_top_widths=[1000],
@@ -170,6 +168,7 @@ def test_circuit_generation(self):
             sigma=64,
             risefall=2,
         )
+        expr.backend = CrossResonanceHamiltonianBackend()
 
         nearlest_16 = 1248
 
@@ -187,7 +186,7 @@ def test_circuit_generation(self):
             pulse.delay(nearlest_16, pulse.DriveChannel(1))
 
         cr_gate = circuit.Gate("cr_gate", num_qubits=2, params=[1000])
-        expr_circs = expr.circuits(backend)
+        expr_circs = expr.circuits()
 
         x0_circ = QuantumCircuit(2, 1)
         x0_circ.append(cr_gate, [0, 1])
@@ -231,8 +230,6 @@ def test_circuit_generation(self):
     def test_circuit_generation_from_sec(self):
         """Test generated circuits when time unit is sec."""
 
-        backend = CrossResonanceHamiltonianBackend()
-
         expr = cr_hamiltonian.CrossResonanceHamiltonian(
             qubits=(0, 1),
             flat_top_widths=[500],
@@ -241,6 +238,7 @@ def test_circuit_generation_from_sec(self):
             sigma=20,
             risefall=2,
         )
+        expr.backend = CrossResonanceHamiltonianBackend()
 
         nearlest_16 = 576
 
@@ -258,7 +256,7 @@ def test_circuit_generation_from_sec(self):
             pulse.delay(nearlest_16, pulse.DriveChannel(1))
 
         cr_gate = circuit.Gate("cr_gate", num_qubits=2, params=[500])
-        expr_circs = expr.circuits(backend)
+        expr_circs = expr.circuits()
 
         x0_circ = QuantumCircuit(2, 1)
         x0_circ.append(cr_gate, [0, 1])
diff --git a/test/test_qubit_spectroscopy.py b/test/test_qubit_spectroscopy.py
index 81ef75cb8b..ecf63b015c 100644
--- a/test/test_qubit_spectroscopy.py
+++ b/test/test_qubit_spectroscopy.py
@@ -134,6 +134,7 @@ def test_spectroscopy12_end2end_classified(self):
         # Note that the backend is not sophisticated enough to simulate an e-f
         # transition so we run the test with g-e.
         spec = EFSpectroscopy(qubit, frequencies, unit="Hz")
+        spec.backend = backend
         spec.set_run_options(meas_level=MeasLevel.CLASSIFIED)
         expdata = spec.run(backend)
         expdata.block_for_results()
@@ -144,6 +145,6 @@ def test_spectroscopy12_end2end_classified(self):
         self.assertEqual(result.quality, "good")
 
         # Test the circuits
-        circ = spec.circuits(backend)[0]
+        circ = spec.circuits()[0]
         self.assertEqual(circ.data[0][0].name, "x")
         self.assertEqual(circ.data[1][0].name, "Spec")

From 3e92a424784caff2ef9b3d5e45b0f204d27eb17f Mon Sep 17 00:00:00 2001
From: Christopher Wood <cjwood@us.ibm.com>
Date: Tue, 26 Oct 2021 12:47:19 -0400
Subject: [PATCH 4/7] Add release note

---
 .../notes/exp-backend-691201fd10046566.yaml   | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 releasenotes/notes/exp-backend-691201fd10046566.yaml

diff --git a/releasenotes/notes/exp-backend-691201fd10046566.yaml b/releasenotes/notes/exp-backend-691201fd10046566.yaml
new file mode 100644
index 0000000000..f941d03737
--- /dev/null
+++ b/releasenotes/notes/exp-backend-691201fd10046566.yaml
@@ -0,0 +1,22 @@
+---
+features:
+  - |
+    Add ``backend`` as an optional ``__init__`` kwarg for all experiments to
+    alow setting the backend at initialization. The backand can also be set
+    and retrieved from the experiment object after construction using the
+    :meth:`~qiskit_experiments.framework.BaseExperiment.backend`
+    property and setter.
+
+    When using the ``backend`` kwarg of
+    :meth:`~qiskit_experiments.framework.BaseExperiment.run` to specify
+    a backend this will temporarily override any currently set backends
+    for that single execution.
+developer:
+  - |
+    Added a ``_set_backend`` method to
+    :class:`~qiskit_experiments.framework.BaseExperiment` that is called
+    when a backend is set via initalization or the ``backend`` setter. This
+    can be overridden in experiment subclasses if required. For example this
+    could be used to extract any needed configuration or properties from the
+    specified backend, or to update experiment options of configuration based
+    on the backend.

From 2c43f77d7a82bd476704feb83927d120a498cc8a Mon Sep 17 00:00:00 2001
From: Christopher Wood <cjwood@us.ibm.com>
Date: Tue, 26 Oct 2021 14:11:31 -0400
Subject: [PATCH 5/7] Address review comments

---
 .../framework/base_experiment.py              | 23 ++++++++-----------
 .../framework/experiment_data.py              |  2 +-
 .../library/characterization/t1.py            | 14 +++++++++++
 .../library/characterization/t2ramsey.py      | 14 +++++++++++
 4 files changed, 39 insertions(+), 14 deletions(-)

diff --git a/qiskit_experiments/framework/base_experiment.py b/qiskit_experiments/framework/base_experiment.py
index bbf5ec07ab..f60a170081 100644
--- a/qiskit_experiments/framework/base_experiment.py
+++ b/qiskit_experiments/framework/base_experiment.py
@@ -22,7 +22,6 @@
 from qiskit.providers import BaseJob
 from qiskit.providers.backend import Backend
 from qiskit.providers.basebackend import BaseBackend as LegacyBackend
-from qiskit.test.mock import FakeBackend
 from qiskit.exceptions import QiskitError
 from qiskit.qobj.utils import MeasLevel
 from qiskit_experiments.framework import Options
@@ -94,7 +93,7 @@ def experiment_type(self) -> str:
         return self._type
 
     @property
-    def physical_qubits(self) -> Tuple[int]:
+    def physical_qubits(self) -> Tuple[int, ...]:
         """Return the device qubits for the experiment."""
         return self._physical_qubits
 
@@ -121,19 +120,17 @@ def _set_backend(self, backend: Backend):
         """
         self._backend = backend
 
-        # Scheduling parameters
-        if not self._backend.configuration().simulator and not isinstance(backend, FakeBackend):
-            timing_constraints = getattr(self.transpile_options, "timing_constraints", {})
-            if "acquire_alignment" not in timing_constraints:
-                timing_constraints["aquire_aligment"] = 16
-            scheduling_method = getattr(self.transpile_options, "scheduling_method", "alap")
-            self.set_transpile_options(
-                timing_constraints=timing_constraints, scheduling_method=scheduling_method
-            )
-
     def copy(self) -> "BaseExperiment":
         """Return a copy of the experiment"""
-        return copy.copy(self)
+        # We want to avoid a deep copy be default for performance so we
+        # need to also copy the Options structures so that if they are
+        # updated on the copy they don't effect the original.
+        ret = copy.copy(self)
+        ret._experiment_options = copy.copy(self._experiment_options)
+        ret._run_options = copy.copy(self._run_options)
+        ret._transpile_options = copy.copy(self._transpile_options)
+        ret._analysis_options = copy.copy(self._analysis_options)
+        return ret
 
     def run(
         self,
diff --git a/qiskit_experiments/framework/experiment_data.py b/qiskit_experiments/framework/experiment_data.py
index f5a12769fb..225a932644 100644
--- a/qiskit_experiments/framework/experiment_data.py
+++ b/qiskit_experiments/framework/experiment_data.py
@@ -53,7 +53,7 @@ def __init__(self, experiment=None, backend=None, parent_id=None, job_ids=None):
     @property
     def experiment(self):
         """Return the experiment for this data.
-        
+
         Returns:
             BaseExperiment: the experiment object.
         """
diff --git a/qiskit_experiments/library/characterization/t1.py b/qiskit_experiments/library/characterization/t1.py
index 55361a9e4c..a0546acda9 100644
--- a/qiskit_experiments/library/characterization/t1.py
+++ b/qiskit_experiments/library/characterization/t1.py
@@ -18,6 +18,7 @@
 
 from qiskit.circuit import QuantumCircuit
 from qiskit.providers.backend import Backend
+from qiskit.test.mock import FakeBackend
 
 from qiskit_experiments.framework import BaseExperiment, Options
 from qiskit_experiments.library.characterization.t1_analysis import T1Analysis
@@ -91,6 +92,19 @@ def __init__(
         # Set experiment options
         self.set_experiment_options(delays=delays, unit=unit)
 
+    def _set_backend(self, backend: Backend):
+        super()._set_backend(backend)
+
+        # Scheduling parameters
+        if not self._backend.configuration().simulator and not isinstance(backend, FakeBackend):
+            timing_constraints = getattr(self.transpile_options, "timing_constraints", {})
+            if "acquire_alignment" not in timing_constraints:
+                timing_constraints["aquire_aligment"] = 16
+            scheduling_method = getattr(self.transpile_options, "scheduling_method", "alap")
+            self.set_transpile_options(
+                timing_constraints=timing_constraints, scheduling_method=scheduling_method
+            )
+
     def circuits(self) -> List[QuantumCircuit]:
         """
         Return a list of experiment circuits
diff --git a/qiskit_experiments/library/characterization/t2ramsey.py b/qiskit_experiments/library/characterization/t2ramsey.py
index 8dc2a3c31c..b46d61a931 100644
--- a/qiskit_experiments/library/characterization/t2ramsey.py
+++ b/qiskit_experiments/library/characterization/t2ramsey.py
@@ -21,6 +21,7 @@
 from qiskit.utils import apply_prefix
 from qiskit.circuit import QuantumCircuit
 from qiskit.providers.backend import Backend
+from qiskit.test.mock import FakeBackend
 
 from qiskit_experiments.framework import BaseExperiment, Options
 from .t2ramsey_analysis import T2RamseyAnalysis
@@ -105,6 +106,19 @@ def __init__(
         super().__init__([qubit], backend=backend)
         self.set_experiment_options(delays=delays, unit=unit, osc_freq=osc_freq)
 
+    def _set_backend(self, backend: Backend):
+        super()._set_backend(backend)
+
+        # Scheduling parameters
+        if not self._backend.configuration().simulator and not isinstance(backend, FakeBackend):
+            timing_constraints = getattr(self.transpile_options, "timing_constraints", {})
+            if "acquire_alignment" not in timing_constraints:
+                timing_constraints["aquire_aligment"] = 16
+            scheduling_method = getattr(self.transpile_options, "scheduling_method", "alap")
+            self.set_transpile_options(
+                timing_constraints=timing_constraints, scheduling_method=scheduling_method
+            )
+
     def circuits(self) -> List[QuantumCircuit]:
         """Return a list of experiment circuits.
 

From e65c4ef099f19d48e02c72cc85f718855ea74cdc Mon Sep 17 00:00:00 2001
From: Christopher Wood <cjwood@us.ibm.com>
Date: Tue, 26 Oct 2021 17:20:40 -0400
Subject: [PATCH 6/7] Make backend first kwarg

---
 .../framework/composite/batch_experiment.py   | 12 ++++++-----
 .../composite/composite_experiment.py         | 20 +++++++++++++------
 .../composite/parallel_experiment.py          | 12 ++++++-----
 .../library/calibration/fine_amplitude.py     |  8 ++++----
 .../library/calibration/ramsey_xy.py          |  4 ++--
 .../library/calibration/rough_frequency.py    | 10 +++++-----
 .../characterization/cr_hamiltonian.py        |  4 ++--
 .../characterization/qubit_spectroscopy.py    |  4 ++--
 .../library/characterization/t1.py            |  4 ++--
 .../library/characterization/t2ramsey.py      | 11 ++++------
 .../library/quantum_volume/qv_experiment.py   |  4 ++--
 .../interleaved_rb_experiment.py              | 13 +++++++++---
 .../randomized_benchmarking/rb_experiment.py  |  4 ++--
 .../tomography/tomography_experiment.py       |  4 ++--
 .../experiments/test_rough_frequency.py       |  4 +++-
 15 files changed, 68 insertions(+), 50 deletions(-)

diff --git a/qiskit_experiments/framework/composite/batch_experiment.py b/qiskit_experiments/framework/composite/batch_experiment.py
index 43ab84d0d7..67ee527a09 100644
--- a/qiskit_experiments/framework/composite/batch_experiment.py
+++ b/qiskit_experiments/framework/composite/batch_experiment.py
@@ -13,21 +13,23 @@
 Batch Experiment class.
 """
 
+from typing import List, Optional
 from collections import OrderedDict
 
 from qiskit import QuantumCircuit
-
-from .composite_experiment import CompositeExperiment
+from qiskit.providers.backend import Backend
+from .composite_experiment import CompositeExperiment, BaseExperiment
 
 
 class BatchExperiment(CompositeExperiment):
     """Batch experiment class"""
 
-    def __init__(self, experiments):
+    def __init__(self, experiments: List[BaseExperiment], backend: Optional[Backend] = None):
         """Initialize a batch experiment.
 
         Args:
-            experiments (List[BaseExperiment]): a list of experiments.
+            experiments: a list of experiments.
+            backend: Optional, the backend to run the experiment on.
         """
 
         # Generate qubit map
@@ -39,7 +41,7 @@ def __init__(self, experiments):
                     self._qubit_map[physical_qubit] = logical_qubit
                     logical_qubit += 1
         qubits = tuple(self._qubit_map.keys())
-        super().__init__(experiments, qubits)
+        super().__init__(experiments, qubits, backend=backend)
 
     def circuits(self):
 
diff --git a/qiskit_experiments/framework/composite/composite_experiment.py b/qiskit_experiments/framework/composite/composite_experiment.py
index 983ee9ec45..484286aade 100644
--- a/qiskit_experiments/framework/composite/composite_experiment.py
+++ b/qiskit_experiments/framework/composite/composite_experiment.py
@@ -13,9 +13,11 @@
 Composite Experiment abstract base class.
 """
 
+from typing import List, Sequence, Optional
 from abc import abstractmethod
 import warnings
 
+from qiskit.providers.backend import Backend
 from qiskit_experiments.framework import BaseExperiment
 from .composite_experiment_data import CompositeExperimentData
 from .composite_analysis import CompositeAnalysis
@@ -27,18 +29,24 @@ class CompositeExperiment(BaseExperiment):
     __analysis_class__ = CompositeAnalysis
     __experiment_data__ = CompositeExperimentData
 
-    def __init__(self, experiments, qubits, experiment_type=None):
+    def __init__(
+        self,
+        experiments: List[BaseExperiment],
+        qubits: Sequence[int],
+        backend: Optional[Backend] = None,
+        experiment_type: Optional[str] = None,
+    ):
         """Initialize the composite experiment object.
 
         Args:
-            experiments (List[BaseExperiment]): a list of experiment objects.
-            qubits (int or Iterable[int]): the number of qubits or list of
-                                           physical qubits for the experiment.
-            experiment_type (str): Optional, composite experiment subclass name.
+            experiments: a list of experiment objects.
+            qubits: the number of qubits or list of physical qubits for the experiment.
+            backend: Optional, the backend to run the experiment on.
+            experiment_type: Optional, composite experiment subclass name.
         """
         self._experiments = experiments
         self._num_experiments = len(experiments)
-        super().__init__(qubits, experiment_type=experiment_type)
+        super().__init__(qubits, backend=backend, experiment_type=experiment_type)
 
     @abstractmethod
     def circuits(self):
diff --git a/qiskit_experiments/framework/composite/parallel_experiment.py b/qiskit_experiments/framework/composite/parallel_experiment.py
index b22a1e5382..4643b3f0e6 100644
--- a/qiskit_experiments/framework/composite/parallel_experiment.py
+++ b/qiskit_experiments/framework/composite/parallel_experiment.py
@@ -12,25 +12,27 @@
 """
 Parallel Experiment class.
 """
+from typing import List, Optional
 
 from qiskit import QuantumCircuit, ClassicalRegister
-
-from .composite_experiment import CompositeExperiment
+from qiskit.providers.backend import Backend
+from .composite_experiment import CompositeExperiment, BaseExperiment
 
 
 class ParallelExperiment(CompositeExperiment):
     """Parallel Experiment class"""
 
-    def __init__(self, experiments):
+    def __init__(self, experiments: List[BaseExperiment], backend: Optional[Backend] = None):
         """Initialize the analysis object.
 
         Args:
-            experiments (List[BaseExperiment]): a list of experiments.
+            experiments: a list of experiments.
+            backend: Optional, the backend to run the experiment on.
         """
         qubits = []
         for exp in experiments:
             qubits += exp.physical_qubits
-        super().__init__(experiments, qubits)
+        super().__init__(experiments, qubits, backend=backend)
 
     def circuits(self):
 
diff --git a/qiskit_experiments/library/calibration/fine_amplitude.py b/qiskit_experiments/library/calibration/fine_amplitude.py
index d2f641a0ec..63538736df 100644
--- a/qiskit_experiments/library/calibration/fine_amplitude.py
+++ b/qiskit_experiments/library/calibration/fine_amplitude.py
@@ -42,9 +42,9 @@ def __init__(
         qubit: int,
         calibrations: BackendCalibrations,
         schedule_name: str,
+        backend: Optional[Backend] = None,
         cal_parameter_name: Optional[str] = "amp",
         auto_update: bool = True,
-        backend: Optional[Backend] = None,
     ):
         """see class :class:`FineAmplitude` for details.
 
@@ -52,20 +52,20 @@ def __init__(
             qubit: The qubit for which to run the fine amplitude calibration.
             calibrations: The calibrations instance with the schedules.
             schedule_name: The name of the schedule to calibrate.
+            backend: Optional, the backend to run the experiment on.
             cal_parameter_name: The name of the parameter in the schedule to update.
             auto_update: Whether or not to automatically update the calibrations. By
                 default this variable is set to True.
-            backend: Optional, the backend to run the experiment on.
-
+            on.
         """
         super().__init__(
             calibrations,
             qubit,
             Gate(name=schedule_name, num_qubits=1, params=[]),
             schedule_name=schedule_name,
+            backend=backend,
             cal_parameter_name=cal_parameter_name,
             auto_update=auto_update,
-            backend=backend,
         )
 
         self.transpile_options.inst_map = calibrations.default_inst_map
diff --git a/qiskit_experiments/library/calibration/ramsey_xy.py b/qiskit_experiments/library/calibration/ramsey_xy.py
index 7f9edb3376..3411a0f5a8 100644
--- a/qiskit_experiments/library/calibration/ramsey_xy.py
+++ b/qiskit_experiments/library/calibration/ramsey_xy.py
@@ -106,20 +106,20 @@ def _default_experiment_options(cls):
     def __init__(
         self,
         qubit: int,
+        backend: Optional[Backend] = None,
         delays: Optional[List] = None,
         unit: str = "s",
         osc_freq: float = 2e6,
-        backend: Optional[Backend] = None,
     ):
         """Create new experiment.
 
         Args:
             qubit: The qubit on which to run the Ramsey XY experiment.
+            backend: Optional, the backend to run the experiment on.
             delays: The delays to scan.
             unit: The unit of the delays.
             osc_freq: the oscillation frequency induced by the user through a virtual
                 Rz rotation. This quantity is given in Hz.
-            backend: Optional, the backend to run the experiment on.
         """
         super().__init__([qubit], backend=backend)
 
diff --git a/qiskit_experiments/library/calibration/rough_frequency.py b/qiskit_experiments/library/calibration/rough_frequency.py
index 4cb720ac10..bc5dc1a77c 100644
--- a/qiskit_experiments/library/calibration/rough_frequency.py
+++ b/qiskit_experiments/library/calibration/rough_frequency.py
@@ -32,10 +32,10 @@ def __init__(
         qubit: int,
         calibrations: BackendCalibrations,
         frequencies: Iterable[float],
+        backend: Optional[Backend] = None,
         unit: str = "Hz",
         auto_update: bool = True,
         absolute: bool = True,
-        backend: Optional[Backend] = None,
     ):
         """See :class:`QubitSpectroscopy` for detailed documentation.
 
@@ -44,13 +44,13 @@ def __init__(
             calibrations: If calibrations is given then running the experiment may update the values
                 of the frequencies stored in calibrations.
             frequencies: The frequencies to scan in the experiment.
+            backend: Optional, the backend to run the experiment on.
             unit: The unit in which the user specifies the frequencies. Can be one of 'Hz', 'kHz',
                 'MHz', 'GHz'. Internally, all frequencies will be converted to 'Hz'.
             auto_update: If set to True, which is the default, then the experiment will
                 automatically update the frequency in the calibrations.
             absolute: Boolean to specify if the frequencies are absolute or relative to the
                 qubit frequency in the backend.
-            backend: Optional, the backend to run the experiment on.
 
         Raises:
             QiskitError: if there are less than three frequency shifts or if the unit is not known.
@@ -60,11 +60,11 @@ def __init__(
             calibrations,
             qubit,
             frequencies,
-            unit,
-            absolute,
+            backend=backend,
+            unit=unit,
+            absolute=absolute,
             updater=Frequency,
             auto_update=auto_update,
-            backend=backend,
         )
 
 
diff --git a/qiskit_experiments/library/characterization/cr_hamiltonian.py b/qiskit_experiments/library/characterization/cr_hamiltonian.py
index ad62bb1e45..ccb640e67d 100644
--- a/qiskit_experiments/library/characterization/cr_hamiltonian.py
+++ b/qiskit_experiments/library/characterization/cr_hamiltonian.py
@@ -130,8 +130,8 @@ def __init__(
         self,
         qubits: Tuple[int, int],
         flat_top_widths: Iterable[float],
-        unit: str = "dt",
         backend: Optional[Backend] = None,
+        unit: str = "dt",
         **kwargs,
     ):
         """Create a new experiment.
@@ -142,8 +142,8 @@ def __init__(
             flat_top_widths: The total duration of the square part of cross resonance pulse(s)
                 to scan. The total pulse duration including Gaussian rising and falling edges
                 is implicitly computed with experiment parameters ``sigma`` and ``risefall``.
-            unit: The time unit of durations.
             backend: Optional, the backend to run the experiment on.
+            unit: The time unit of durations.
             kwargs: Pulse parameters. See :meth:`experiment_options` for details.
 
         Raises:
diff --git a/qiskit_experiments/library/characterization/qubit_spectroscopy.py b/qiskit_experiments/library/characterization/qubit_spectroscopy.py
index f0dbeffbbc..09314d0131 100644
--- a/qiskit_experiments/library/characterization/qubit_spectroscopy.py
+++ b/qiskit_experiments/library/characterization/qubit_spectroscopy.py
@@ -95,9 +95,9 @@ def __init__(
         self,
         qubit: int,
         frequencies: Iterable[float],
+        backend: Optional[Backend] = None,
         unit: str = "Hz",
         absolute: bool = True,
-        backend: Optional[Backend] = None,
     ):
         """
         A spectroscopy experiment run by setting the frequency of the qubit drive.
@@ -111,11 +111,11 @@ def __init__(
         Args:
             qubit: The qubit on which to run spectroscopy.
             frequencies: The frequencies to scan in the experiment.
+            backend: Optional, the backend to run the experiment on.
             unit: The unit in which the user specifies the frequencies. Can be one of 'Hz', 'kHz',
                 'MHz', 'GHz'. Internally, all frequencies will be converted to 'Hz'.
             absolute: Boolean to specify if the frequencies are absolute or relative to the
                 qubit frequency in the backend.
-            backend: Optional, the backend to run the experiment on.
 
         Raises:
             QiskitError: if there are less than three frequency shifts or if the unit is not known.
diff --git a/qiskit_experiments/library/characterization/t1.py b/qiskit_experiments/library/characterization/t1.py
index a0546acda9..1a01cc722e 100644
--- a/qiskit_experiments/library/characterization/t1.py
+++ b/qiskit_experiments/library/characterization/t1.py
@@ -67,8 +67,8 @@ def __init__(
         self,
         qubit: int,
         delays: Union[List[float], np.array],
-        unit: Optional[str] = "s",
         backend: Optional[Backend] = None,
+        unit: Optional[str] = "s",
     ):
         """
         Initialize the T1 experiment class
@@ -76,9 +76,9 @@ def __init__(
         Args:
             qubit: the qubit whose T1 is to be estimated
             delays: delay times of the experiments
+            backend: Optional, the backend to run the experiment on.
             unit: Optional, unit of the delay times. Supported units:
                   's', 'ms', 'us', 'ns', 'ps', 'dt'.
-            backend: Optional, the backend to run the experiment on.
 
         Raises:
             ValueError: if the number of delays is smaller than 3
diff --git a/qiskit_experiments/library/characterization/t2ramsey.py b/qiskit_experiments/library/characterization/t2ramsey.py
index b46d61a931..dbef1e8186 100644
--- a/qiskit_experiments/library/characterization/t2ramsey.py
+++ b/qiskit_experiments/library/characterization/t2ramsey.py
@@ -82,25 +82,22 @@ def __init__(
         self,
         qubit: int,
         delays: Union[List[float], np.array],
+        backend: Optional[Backend] = None,
         unit: str = "s",
         osc_freq: float = 0.0,
-        backend: Optional[Backend] = None,
     ):
         """
-        **T2Ramsey class**
-
         Initialize the T2Ramsey class.
 
         Args:
             qubit: the qubit under test.
             delays: delay times of the experiments.
+            backend: Optional, the backend to run the experiment on.
             unit: Optional, time unit of `delays`.
                 Supported units: 's', 'ms', 'us', 'ns', 'ps', 'dt'. The unit is
                 used for both T2Ramsey and for the frequency.
-            osc_freq: the oscillation frequency induced by the user. \
-            The frequency is given in Hz.
-            backend: Optional, the backend to run the experiment on.
-
+            osc_freq: the oscillation frequency induced by the user.
+                      The frequency is given in Hz.
         """
 
         super().__init__([qubit], backend=backend)
diff --git a/qiskit_experiments/library/quantum_volume/qv_experiment.py b/qiskit_experiments/library/quantum_volume/qv_experiment.py
index f8920afc8c..e2c0ce076e 100644
--- a/qiskit_experiments/library/quantum_volume/qv_experiment.py
+++ b/qiskit_experiments/library/quantum_volume/qv_experiment.py
@@ -73,9 +73,9 @@ class QuantumVolume(BaseExperiment):
     def __init__(
         self,
         qubits: Union[int, Iterable[int]],
+        backend: Optional[Backend] = None,
         trials: Optional[int] = 100,
         seed: Optional[Union[int, Generator]] = None,
-        backend: Optional[Backend] = None,
         simulation_backend: Optional[Backend] = None,
     ):
         """Initialize a quantum volume experiment.
@@ -83,10 +83,10 @@ def __init__(
         Args:
             qubits: The number of qubits or list of
                     physical qubits for the experiment.
+            backend: Optional, the backend to run the experiment on.
             trials: The number of trials to run the quantum volume circuit.
             seed: Seed or generator object for random number
                   generation. If None default_rng will be used.
-            backend: Optional, the backend to run the experiment on.
             simulation_backend: The simulator backend to use to generate
                 the expected results. the simulator must have a 'save_probabilities'
                 method. If None :class:`AerSimulator` simulator will be used
diff --git a/qiskit_experiments/library/randomized_benchmarking/interleaved_rb_experiment.py b/qiskit_experiments/library/randomized_benchmarking/interleaved_rb_experiment.py
index e24cca0fd7..b6c9ce92a5 100644
--- a/qiskit_experiments/library/randomized_benchmarking/interleaved_rb_experiment.py
+++ b/qiskit_experiments/library/randomized_benchmarking/interleaved_rb_experiment.py
@@ -52,10 +52,10 @@ def __init__(
         interleaved_element: Union[QuantumCircuit, Instruction, Clifford],
         qubits: Union[int, Iterable[int]],
         lengths: Iterable[int],
+        backend: Optional[Backend] = None,
         num_samples: int = 3,
         seed: Optional[Union[int, Generator]] = None,
         full_sampling: bool = False,
-        backend: Optional[Backend] = None,
     ):
         """Initialize an interleaved randomized benchmarking experiment.
 
@@ -65,6 +65,7 @@ def __init__(
             qubits: The number of qubits or list of
                     physical qubits for the experiment.
             lengths: A list of RB sequences lengths.
+            backend: The backend to run the experiment on.
             num_samples: Number of samples to generate for each
                          sequence length
             seed: Seed or generator object for random number
@@ -73,10 +74,16 @@ def __init__(
                            all lengths. If False for sample of lengths longer
                            sequences are constructed by appending additional
                            Clifford samples to shorter sequences.
-            backend: The backend to run the experiment on.
         """
         self._set_interleaved_element(interleaved_element)
-        super().__init__(qubits, lengths, num_samples, seed, full_sampling, backend=backend)
+        super().__init__(
+            qubits,
+            lengths,
+            backend=backend,
+            num_samples=num_samples,
+            seed=seed,
+            full_sampling=full_sampling,
+        )
 
     def _sample_circuits(self, lengths, seed=None):
         circuits = []
diff --git a/qiskit_experiments/library/randomized_benchmarking/rb_experiment.py b/qiskit_experiments/library/randomized_benchmarking/rb_experiment.py
index ad004a09b2..231b7eee06 100644
--- a/qiskit_experiments/library/randomized_benchmarking/rb_experiment.py
+++ b/qiskit_experiments/library/randomized_benchmarking/rb_experiment.py
@@ -63,10 +63,10 @@ def __init__(
         self,
         qubits: Union[int, Iterable[int]],
         lengths: Iterable[int],
+        backend: Optional[Backend] = None,
         num_samples: int = 3,
         seed: Optional[Union[int, Generator]] = None,
         full_sampling: Optional[bool] = False,
-        backend: Optional[Backend] = None,
     ):
         """Initialize a standard randomized benchmarking experiment.
 
@@ -74,6 +74,7 @@ def __init__(
             qubits: The number of qubits or list of
                     physical qubits for the experiment.
             lengths: A list of RB sequences lengths.
+            backend: The backend to run the experiment on.
             num_samples: Number of samples to generate for each sequence length.
             seed: Seed or generator object for random number
                   generation. If None default_rng will be used.
@@ -82,7 +83,6 @@ def __init__(
                            sequences are constructed by appending additional
                            Clifford samples to shorter sequences.
                            The default is False.
-            backend: The backend to run the experiment on.
         """
         # Initialize base experiment
         super().__init__(qubits, backend=backend)
diff --git a/qiskit_experiments/library/tomography/tomography_experiment.py b/qiskit_experiments/library/tomography/tomography_experiment.py
index 68e6f15afd..3685c3e2b1 100644
--- a/qiskit_experiments/library/tomography/tomography_experiment.py
+++ b/qiskit_experiments/library/tomography/tomography_experiment.py
@@ -54,19 +54,20 @@ def _default_experiment_options(cls) -> Options:
     def __init__(
         self,
         circuit: Union[QuantumCircuit, Instruction, BaseOperator],
+        backend: Optional[Backend] = None,
         measurement_basis: Optional[BaseTomographyMeasurementBasis] = None,
         measurement_qubits: Optional[Iterable[int]] = None,
         preparation_basis: Optional[BaseTomographyPreparationBasis] = None,
         preparation_qubits: Optional[Iterable[int]] = None,
         basis_indices: Optional[Iterable[Tuple[List[int], List[int]]]] = None,
         qubits: Optional[Iterable[int]] = None,
-        backend: Optional[Backend] = None,
     ):
         """Initialize a tomography experiment.
 
         Args:
             circuit: the quantum process circuit. If not a quantum circuit
                 it must be a class that can be appended to a quantum circuit.
+            backend: The backend to run the experiment on.
             measurement_basis: Tomography basis for measurements.
             measurement_qubits: Optional, the qubits to be measured. These should refer
                 to the logical qubits in the state circuit.
@@ -76,7 +77,6 @@ def __init__(
             basis_indices: Optional, the basis elements to be measured. If None
                 All basis elements will be measured.
             qubits: Optional, the physical qubits for the initial state circuit.
-            backend: The backend to run the experiment on.
 
         Raises:
             QiskitError: if input params are invalid.
diff --git a/test/calibration/experiments/test_rough_frequency.py b/test/calibration/experiments/test_rough_frequency.py
index 69a013bb81..1dc2d220ed 100644
--- a/test/calibration/experiments/test_rough_frequency.py
+++ b/test/calibration/experiments/test_rough_frequency.py
@@ -37,7 +37,9 @@ def test_init(self):
         auto_update = False
         absolute = False
 
-        freq = RoughFrequencyCal(qubit, cals, frequencies, unit, auto_update, absolute)
+        freq = RoughFrequencyCal(
+            qubit, cals, frequencies, unit=unit, auto_update=auto_update, absolute=absolute
+        )
 
         self.assertEqual(freq.physical_qubits, (qubit,))
         self.assertEqual(freq._frequencies, [1000, 2000, 3000])

From fe770bf13ff27f0823f448d1e92f9ff9aa94e156 Mon Sep 17 00:00:00 2001
From: Naoki Kanazawa <nkanazawa1989@gmail.com>
Date: Wed, 27 Oct 2021 12:19:53 +0900
Subject: [PATCH 7/7] Update
 qiskit_experiments/library/characterization/fine_amplitude.py

---
 qiskit_experiments/library/characterization/fine_amplitude.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qiskit_experiments/library/characterization/fine_amplitude.py b/qiskit_experiments/library/characterization/fine_amplitude.py
index fadc9862df..3c4c4c5fa2 100644
--- a/qiskit_experiments/library/characterization/fine_amplitude.py
+++ b/qiskit_experiments/library/characterization/fine_amplitude.py
@@ -134,7 +134,7 @@ def __init__(self, qubit: int, gate: Gate, backend: Optional[Backend] = None):
             backend: Optional, the backend to run the experiment on.
         """
         super().__init__([qubit], backend=backend)
-        self.experiment_options.gate = gate
+        self.set_experiment_options(gate=gate)
 
     def _pre_circuit(self) -> QuantumCircuit:
         """Return a preparation circuit.