Remove remaining code usage deprecated in Qiskit 0.46

[wshanks]

This change adjusts for several remaining changes in Qiskit 1.0:

• qiskit.providers.basicaer was removed in Qiskit 1.0 (see Rename BasicAer to BasicProvider and refactor interface to follow BackendV2 Qiskit/qiskit#11422). Here its use is replaced with qiskit-aer.

• qiskit.providers.fake_provider.FakeJob was removed in Qiskit 1.0 (see Remove provider-specific fake backends,FakeProvider class and related tools in 1.0 Qiskit/qiskit#11376). Here the FakeJob already in qiskit_experiments.test is used instead. This update was missed in f22bb7b which switched the other fake_provider usage.

• Replace qiskit.provider.FakeProvider with a custom subclass of ProviderV1. FakeProvider was moved out of Qiskit 1.0 to qiskit-ibm-runtime.

• calibration/test_rabi.py was modified to make the data for a test of bad data worse as the test started fitting the data as good with the original parameters and qiskit-aer in place of basicaer.

• In the readout mitigation manual, a use of plot_histogram was exchanged for one of plot_distribution.

• Guard FakeBackendV2 import that was removed in Qiskit 1.0. Try to import FakeBackendV2 from qiskit-ibm-runtime as well.

Also, this change unpins qiskit which had to be pinned in f22bb7b until these fixes could be merged since 0.46.0 was released with deprecation warnings for some of the usage changed here.

[wshanks]

@coruscating This fixes the tests against Qiskit main which I noticed had started failing again.

[wshanks]

It seemed like this test chose somewhat arbitrary input data to be "bad" but changing simulators made it start fitting as good again. I made the data worse so that it should more reliably fit as bad.

[coruscating]

This works with Qiskit 0.46, but FakeBackendV2 has also been removed in 1.0 (the code is still there but the import path is gone). I think this import was probably meant to be updated in #1369:

https://github.com/Qiskit-Extensions/qiskit-experiments/blob/f22bb7b67893a1b75f7d0f1fecdb0bd63284e244/qiskit_experiments/framework/backend_data.py#L20

[coruscating]

This is good for now. I noticed our FakeJob is implemented differently from the removed FakeJob and also from current Jobs. For example, the qiskit-ibm-runtime Job doesn't have time_per_step() implemented currently. If we're using our own FakeJob going forward, we should make sure it matches the external specs.

[wshanks]

That sounds good. If possible, I would like to see us push more for external specs. The Qiskit base classes are minimal and we rely on a lot of private attributes of the provider classes in a way that seems very brittle.

[wshanks]

Maybe we should remove that now to try to get the cron tests working again.

I added a change for it. I think the cron tests will still fail because we need qiskit-ibm-runtime which still depends on qiskit-ibm-provider in its latest release and qiskit-ibm-provider is not compatible with qiskit 1.0. If we don't want to wait for qiskit-ibm-runtime, we might need to fork it, patch out the qiskit-ibm-provider part (sloppily since we just need the fake backends), and install from the fork until qiskit-ibm-runtime can properly remove the qiskit-ibm-provider parts.

I think we should deprecate BackendData.is_simulator. It is not used in the repo and I am not sure it is that useful to users. The online simulators are deprecated and besides that the user should be able to tell from context if a backend is a simulator (they won't be iterating over a list from a provider with a mix of simulators and hardware backends).

[coruscating]

LGTM!