Remove legacy providers interface

qiskit/algorithms/amplitude_amplifiers/grover.py

@@ -19,7 +19,7 @@
 import numpy as np
 
 from qiskit import ClassicalRegister, QuantumCircuit
-from qiskit.providers import Backend, BaseBackend
+from qiskit.providers import Backend
 from qiskit.quantum_info import partial_trace
 from qiskit.utils import QuantumInstance
 from .amplification_problem import AmplificationProblem
@@ -112,7 +112,7 @@ def __init__(
         iterations: Optional[Union[List[int], Iterator[int], int]] = None,
         growth_rate: Optional[float] = None,
         sample_from_iterations: bool = False,
-        quantum_instance: Optional[Union[QuantumInstance, Backend, BaseBackend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
         r"""
         Args:
@@ -172,14 +172,12 @@ def quantum_instance(self) -> Optional[QuantumInstance]:
         return self._quantum_instance
 
     @quantum_instance.setter
-    def quantum_instance(
-        self, quantum_instance: Union[QuantumInstance, BaseBackend, Backend]
-    ) -> None:
+    def quantum_instance(self, quantum_instance: Union[QuantumInstance, Backend]) -> None:
         """Set quantum instance.
         Args:
             quantum_instance: The quantum instance used to run this algorithm.
         """
-        if isinstance(quantum_instance, (BaseBackend, Backend)):
+        if isinstance(quantum_instance, Backend):
             quantum_instance = QuantumInstance(quantum_instance)
         self._quantum_instance = quantum_instance
 

qiskit/algorithms/amplitude_estimators/ae.py

@@ -19,7 +19,7 @@
 from scipy.optimize import bisect
 
 from qiskit import QuantumCircuit, ClassicalRegister
-from qiskit.providers import BaseBackend, Backend
+from qiskit.providers import Backend
 from qiskit.utils import QuantumInstance
 from .amplitude_estimator import AmplitudeEstimator, AmplitudeEstimatorResult
 from .ae_utils import pdf_a, derivative_log_pdf_a, bisect_max
@@ -58,7 +58,7 @@ def __init__(
         num_eval_qubits: int,
         phase_estimation_circuit: Optional[QuantumCircuit] = None,
         iqft: Optional[QuantumCircuit] = None,
-        quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
         r"""
         Args:
@@ -98,15 +98,13 @@ def quantum_instance(self) -> Optional[QuantumInstance]:
         return self._quantum_instance
 
     @quantum_instance.setter
-    def quantum_instance(
-        self, quantum_instance: Union[QuantumInstance, BaseBackend, Backend]
-    ) -> None:
+    def quantum_instance(self, quantum_instance: Union[QuantumInstance, Backend]) -> None:
         """Set quantum instance.
 
         Args:
             quantum_instance: The quantum instance used to run this algorithm.
         """
-        if isinstance(quantum_instance, (BaseBackend, Backend)):
+        if isinstance(quantum_instance, Backend):
             quantum_instance = QuantumInstance(quantum_instance)
         self._quantum_instance = quantum_instance
 

qiskit/algorithms/amplitude_estimators/fae.py

@@ -16,7 +16,7 @@
 import numpy as np
 
 from qiskit.circuit import QuantumCircuit, ClassicalRegister
-from qiskit.providers import BaseBackend, Backend
+from qiskit.providers import Backend
 from qiskit.utils import QuantumInstance
 from qiskit.algorithms.exceptions import AlgorithmError
 
@@ -50,7 +50,7 @@ def __init__(
         delta: float,
         maxiter: int,
         rescale: bool = True,
-        quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
         r"""
         Args:
@@ -83,15 +83,13 @@ def quantum_instance(self) -> Optional[QuantumInstance]:
         return self._quantum_instance
 
     @quantum_instance.setter
-    def quantum_instance(
-        self, quantum_instance: Union[QuantumInstance, BaseBackend, Backend]
-    ) -> None:
+    def quantum_instance(self, quantum_instance: Union[QuantumInstance, Backend]) -> None:
         """Set quantum instance.
 
         Args:
             quantum_instance: The quantum instance used to run this algorithm.
         """
-        if isinstance(quantum_instance, (BaseBackend, Backend)):
+        if isinstance(quantum_instance, Backend):
             quantum_instance = QuantumInstance(quantum_instance)
         self._quantum_instance = quantum_instance
 

qiskit/algorithms/amplitude_estimators/iae.py

@@ -17,7 +17,7 @@
 from scipy.stats import beta
 
 from qiskit import ClassicalRegister, QuantumCircuit
-from qiskit.providers import BaseBackend, Backend
+from qiskit.providers import Backend
 from qiskit.utils import QuantumInstance
 
 from .amplitude_estimator import AmplitudeEstimator, AmplitudeEstimatorResult
@@ -52,7 +52,7 @@ def __init__(
         alpha: float,
         confint_method: str = "beta",
         min_ratio: float = 2,
-        quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
         r"""
         The output of the algorithm is an estimate for the amplitude `a`, that with at least
@@ -107,15 +107,13 @@ def quantum_instance(self) -> Optional[QuantumInstance]:
         return self._quantum_instance
 
     @quantum_instance.setter
-    def quantum_instance(
-        self, quantum_instance: Union[QuantumInstance, BaseBackend, Backend]
-    ) -> None:
+    def quantum_instance(self, quantum_instance: Union[QuantumInstance, Backend]) -> None:
         """Set quantum instance.
 
         Args:
             quantum_instance: The quantum instance used to run this algorithm.
         """
-        if isinstance(quantum_instance, (BaseBackend, Backend)):
+        if isinstance(quantum_instance, Backend):
             quantum_instance = QuantumInstance(quantum_instance)
         self._quantum_instance = quantum_instance
 

qiskit/algorithms/amplitude_estimators/mlae.py

@@ -17,7 +17,6 @@
 from scipy.optimize import brute
 from scipy.stats import norm, chi2
 
-from qiskit.providers import BaseBackend
 from qiskit.providers import Backend
 from qiskit import ClassicalRegister, QuantumRegister, QuantumCircuit
 from qiskit.utils import QuantumInstance
@@ -52,7 +51,7 @@ def __init__(
         self,
         evaluation_schedule: Union[List[int], int],
         minimizer: Optional[MINIMIZER] = None,
-        quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
         r"""
         Args:
@@ -109,15 +108,13 @@ def quantum_instance(self) -> Optional[QuantumInstance]:
         return self._quantum_instance
 
     @quantum_instance.setter
-    def quantum_instance(
-        self, quantum_instance: Union[QuantumInstance, BaseBackend, Backend]
-    ) -> None:
+    def quantum_instance(self, quantum_instance: Union[QuantumInstance, Backend]) -> None:
         """Set quantum instance.
 
         Args:
             quantum_instance: The quantum instance used to run this algorithm.
         """
-        if isinstance(quantum_instance, (BaseBackend, Backend)):
+        if isinstance(quantum_instance, Backend):
             quantum_instance = QuantumInstance(quantum_instance)
         self._quantum_instance = quantum_instance
 

qiskit/algorithms/aux_ops_evaluator.py

@@ -23,15 +23,15 @@
     OperatorBase,
     ExpectationBase,
 )
-from qiskit.providers import BaseBackend, Backend
+from qiskit.providers import Backend
 from qiskit.quantum_info import Statevector
 from qiskit.utils import QuantumInstance
 
 from .list_or_dict import ListOrDict
 
 
 def eval_observables(
-    quantum_instance: Union[QuantumInstance, BaseBackend, Backend],
+    quantum_instance: Union[QuantumInstance, Backend],
     quantum_state: Union[
         Statevector,
         QuantumCircuit,
@@ -161,7 +161,7 @@ def _compute_std_devs(
     observables_expect_sampled: OperatorBase,
     observables: ListOrDict[OperatorBase],
     expectation: ExpectationBase,
-    quantum_instance: Union[QuantumInstance, BaseBackend, Backend],
+    quantum_instance: Union[QuantumInstance, Backend],
 ) -> List[complex]:
     """
     Calculates a list of standard deviations from expectation values of observables provided.

qiskit/algorithms/factorizers/shor.py

@@ -25,7 +25,6 @@
 from qiskit.circuit import Gate, Instruction, ParameterVector
 from qiskit.circuit.library import QFT
 from qiskit.providers import Backend
-from qiskit.providers import BaseBackend
 from qiskit.quantum_info import partial_trace
 from qiskit.utils import summarize_circuits
 from qiskit.utils.arithmetic import is_power
@@ -51,9 +50,7 @@ class Shor:
     See also https://arxiv.org/abs/quant-ph/0205095
     """
 
-    def __init__(
-        self, quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None
-    ) -> None:
+    def __init__(self, quantum_instance: Optional[Union[QuantumInstance, Backend]] = None) -> None:
         """
         Args:
             quantum_instance: Quantum Instance or Backend
@@ -69,11 +66,9 @@ def quantum_instance(self) -> Optional[QuantumInstance]:
         return self._quantum_instance
 
     @quantum_instance.setter
-    def quantum_instance(
-        self, quantum_instance: Union[QuantumInstance, BaseBackend, Backend]
-    ) -> None:
+    def quantum_instance(self, quantum_instance: Union[QuantumInstance, Backend]) -> None:
         """Sets quantum instance."""
-        if isinstance(quantum_instance, (BaseBackend, Backend)):
+        if isinstance(quantum_instance, Backend):
             quantum_instance = QuantumInstance(quantum_instance)
         self._quantum_instance = quantum_instance
 

qiskit/algorithms/linear_solvers/hhl.py

@@ -29,7 +29,7 @@
     ListOp,
     ExpectationFactory,
 )
-from qiskit.providers import Backend, BaseBackend
+from qiskit.providers import Backend
 from qiskit.quantum_info.operators.base_operator import BaseOperator
 from qiskit.utils import QuantumInstance
 
@@ -100,7 +100,7 @@ def __init__(
         self,
         epsilon: float = 1e-2,
         expectation: Optional[ExpectationBase] = None,
-        quantum_instance: Optional[Union[Backend, BaseBackend, QuantumInstance]] = None,
+        quantum_instance: Optional[Union[Backend, QuantumInstance]] = None,
     ) -> None:
         r"""
         Args:
@@ -142,9 +142,7 @@ def quantum_instance(self) -> Optional[QuantumInstance]:
         return None if self._sampler is None else self._sampler.quantum_instance
 
     @quantum_instance.setter
-    def quantum_instance(
-        self, quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]]
-    ) -> None:
+    def quantum_instance(self, quantum_instance: Optional[Union[QuantumInstance, Backend]]) -> None:
         """Set quantum instance.
 
         Args:

qiskit/algorithms/minimum_eigen_solvers/qaoa.py

@@ -20,7 +20,6 @@
 from qiskit.opflow import OperatorBase, ExpectationBase
 from qiskit.opflow.gradients import GradientBase
 from qiskit.providers import Backend
-from qiskit.providers import BaseBackend
 from qiskit.utils.quantum_instance import QuantumInstance
 from qiskit.utils.validation import validate_min
 from qiskit.circuit.library.n_local.qaoa_ansatz import QAOAAnsatz
@@ -65,7 +64,7 @@ def __init__(
         include_custom: bool = False,
         max_evals_grouped: int = 1,
         callback: Optional[Callable[[int, np.ndarray, float, float], None]] = None,
-        quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
         """
         Args:

qiskit/algorithms/minimum_eigen_solvers/vqe.py

@@ -24,7 +24,6 @@
 
 from qiskit.circuit import QuantumCircuit, Parameter
 from qiskit.circuit.library import RealAmplitudes
-from qiskit.providers import BaseBackend
 from qiskit.providers import Backend
 from qiskit.opflow import (
     OperatorBase,
@@ -145,7 +144,7 @@ def __init__(
         include_custom: bool = False,
         max_evals_grouped: int = 1,
         callback: Optional[Callable[[int, np.ndarray, float, float], None]] = None,
-        quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
         """
 
@@ -254,9 +253,7 @@ def quantum_instance(self) -> Optional[QuantumInstance]:
         return self._quantum_instance
 
     @quantum_instance.setter
-    def quantum_instance(
-        self, quantum_instance: Union[QuantumInstance, BaseBackend, Backend]
-    ) -> None:
+    def quantum_instance(self, quantum_instance: Union[QuantumInstance, Backend]) -> None:
         """Sets quantum_instance"""
         if not isinstance(quantum_instance, QuantumInstance):
             quantum_instance = QuantumInstance(quantum_instance)

qiskit/algorithms/phase_estimators/hamiltonian_phase_estimation.py

@@ -25,7 +25,7 @@
     PauliSumOp,
     StateFn,
 )
-from qiskit.providers import BaseBackend
+from qiskit.providers import Backend
 from .phase_estimation import PhaseEstimation
 from .hamiltonian_phase_estimation_result import HamiltonianPhaseEstimationResult
 from .phase_estimation_scale import PhaseEstimationScale
@@ -88,7 +88,7 @@ class HamiltonianPhaseEstimation:
     def __init__(
         self,
         num_evaluation_qubits: int,
-        quantum_instance: Optional[Union[QuantumInstance, BaseBackend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
         """
         Args:

qiskit/algorithms/phase_estimators/ipe.py

@@ -19,7 +19,7 @@
 import qiskit
 from qiskit.circuit import QuantumCircuit, QuantumRegister
 from qiskit.circuit.classicalregister import ClassicalRegister
-from qiskit.providers import BaseBackend, Backend
+from qiskit.providers import Backend
 from qiskit.utils import QuantumInstance
 from .phase_estimator import PhaseEstimator
 from .phase_estimator import PhaseEstimatorResult
@@ -38,7 +38,7 @@ class IterativePhaseEstimation(PhaseEstimator):
     def __init__(
         self,
         num_iterations: int,
-        quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
 
         """Args:
@@ -48,7 +48,7 @@ def __init__(
         Raises:
           ValueError: if num_iterations is not greater than zero.
         """
-        if isinstance(quantum_instance, (Backend, BaseBackend)):
+        if isinstance(quantum_instance, Backend):
             quantum_instance = QuantumInstance(quantum_instance)
         self._quantum_instance = quantum_instance
         if num_iterations <= 0:

qiskit/algorithms/phase_estimators/phase_estimation.py

@@ -21,7 +21,7 @@
 import qiskit
 from qiskit import circuit
 from qiskit.circuit.classicalregister import ClassicalRegister
-from qiskit.providers import BaseBackend, Backend
+from qiskit.providers import Backend
 from qiskit.utils import QuantumInstance
 from qiskit.result import Result
 from .phase_estimation_result import PhaseEstimationResult, _sort_phases
@@ -81,7 +81,7 @@ class PhaseEstimation(PhaseEstimator):
     def __init__(
         self,
         num_evaluation_qubits: int,
-        quantum_instance: Optional[Union[QuantumInstance, BaseBackend, Backend]] = None,
+        quantum_instance: Optional[Union[QuantumInstance, Backend]] = None,
     ) -> None:
         """
         Args:
@@ -94,7 +94,7 @@ def __init__(
         if num_evaluation_qubits is not None:
             self._num_evaluation_qubits = num_evaluation_qubits
 
-        if isinstance(quantum_instance, (Backend, BaseBackend)):
+        if isinstance(quantum_instance, Backend):
             quantum_instance = QuantumInstance(quantum_instance)
         self._quantum_instance = quantum_instance