Qiskit 2.0 Compatibility

[kt474]

Summary

Since support for pulse gates is being sunset, the Channel related imports and code have been removed:

• fake_backend.py: AcquireChannel, DriveChannel, MeasureChannel, ControlChannel
• backend_configuration.py: AcquireChannel, Channel, ControlChannel, DriveChannel,MeasureChannel
• ibm_backend.py: AcquireChannel, ControlChannel, DriveChannel,MeasureChannel
• pulse_defaults.py: InstructionScheduleMap and PulseQobjDef.
• PulseBackendConfiguration has been removed, all backend configurations will be returned as QasmBackendConfiguration.
• c_if and condition_bit removed in Remove condition/c_if, duration, and unit from instructions qiskit#13506
• has_calibration_for and calibrations removed in Remove calibrations APIs and related functionality  qiskit#13861

Non pulse related:

• qiskit.circuit.bit removed in Move Bit and Register to live in Rust space qiskit#13860
• The deprecated EfficientSU2 has been replaced with efficient_su2

Without Channel, PulseDefaults are no longer needed for the backend target.

I'll handle the DD related pulse deprecations in a separate PR. Also we should clean up a lot of the backend defaults code since it will no longer be necessary.

Details and comments

Fixes #

[wshanks]

Perhaps all the defs_*.json files for the fake backends should also be deleted in this PR?

[wshanks]

I think I tested with a build of Qiskit 2.0 before Qiskit/qiskit#13860 was merged so I missed the qiskit.circuit.bit issue. I think the other things you highlighted (besides the docstring) are addressed in #2162 @eliarbel

[eliarbel]

I think the other things you highlighted (besides the docstring) are addressed in #2162 @eliarbel

You're right @wshanks . I only noticed #2162 after I reviewed this PR though :-)

[kt474]

Addressed all comments and merged #2161 into this branch.

Passes all unit tests against Qiskit 2.0rc1 except the qiskit-aer import issues in the Neat tests which will be fixed in Qiskit/qiskit-aer#2327 (so we'll need a release on the aer side too).

[eliarbel]

Thanks @kt474 for addressing the previous comments and putting this all together in a single PR, it helps!
I've left some more requests for changes and questions in line.

[wshanks]

The removal of PulseBackendConfiguration looks good except for one small thing.

[eliarbel]

This LGTM now given the clarification from Jessie about IBMBackend API and the removal of PulseBackendConfiguration.
There are still a few removed tests in test_schedulers.py which could be kept but I don't think worth blocking this PR on at this stage.

[ElePT]

Addressed all comments and merged #2161 into this branch.

Passes all unit tests against Qiskit 2.0rc1 except the qiskit-aer import issues in the Neat tests which will be fixed in Qiskit/qiskit-aer#2327 (so we'll need a release on the aer side too).

Qiskit/qiskit-aer#2327 is included in the latest release of Aer that just came out: qiskit-aer 0.17.0.

[kt474]

Qiskit/qiskit-aer#2327 is included in the latest release of Aer that just came out: qiskit-aer 0.17.0.

All unit tests passing on both Qiskit 1.4.1 and 2.0rc1 with the latest aer release. Going to merge now, other bugs found will be handled in separate PRs.