qiskit_algorithms namespace is not supported.

[airwoodix]

Environment

• Qiskit Optimization version: 0.5.0
• Python version: 3.11
• Operating system: Linux

What is happening?

MinimumEigenOptimizer doesn't support algorithms from qiskit-algorithms.

The qiskit.algorithms namespace is deprecated since qiskit-terra v0.25.0. The qiskit_algorithms namespace from qiskit-algorithms should be a drop-in replacement (for the transition period).

How can we reproduce the issue?

For example:

from qiskit_algorithms.minimum_eigensolvers import QAOA
from qiskit_optimization.algorithms import MinimumEigenOptimizer

_ = MinimumEigenOptimizer(min_eigen_solver=QAOA(...))

fails with:

TypeError: MinimumEigenOptimizer supports qiskit.algorithms.minimum_eigensolvers.SamplingMinimumEigensolver, qiskit.algorithms.minimum_eigensolvers.NumPyMinimumEigensolver, and qiskit.algorithms.minimum_eigen_solvers.MinimumEigensolver. But <class 'qiskit_algorithms.minimum_eigensolvers.qaoa.QAOA'> is given.

raised at

qiskit-optimization/qiskit_optimization/algorithms/minimum_eigen_optimizer.py

Line 164 in 5e8bc0f

raise TypeError(

What should happen?

It should be possible to use legacy qiskit.algorithms and qiskit_algorithms namespaces interchangeably (until the latter diverges).

Any suggestions?

To ease up the transition and keep the type annotations correct, one could prefer qiskit_algorithms if it is present:

try:
    from qiskit_algorithms.minimum_eigensolvers import ...
except ImportError:
    from qiskit.algorithms.minimum_eigensolvers import ...
)

The TypeError message should already now be informative enough to figure out what is happening.

[t-imamichi]

It has been resolved by #537

[airwoodix]

Awesome, thanks!