Support for PrimitivesV2

[1ucian0]

The primitives in qiskit_aer/primitives implement qiskit_aer.primitives.sampler.Sampler and qiskit_aer.primitives.estimator.Estimator that are subclassing qiskit.primitives.base.base_sampler.BaseSamplerV1 and qiskit.primitives.base.base_estimator.BaseEstimatorV1. With the introduction of BaseSamplerV2 and BaseEstimatorV2, it would be great to have qiskit_aer.primitives.sampler.SamplerV2 and and qiskit_aer.primitives.estimator.EstimatorV2.

[ikkoham]

I implemented EstimatorV2Converter Qiskit/qiskit#11899. It may be useful for EstimatorV2.
Unfortunately, it is not possible to implement SamplerV2Converter because result data are completely different.
But, there are no advantages for SamplerV2 because simulator specific improvement does not exist. BackendSamplerV2 + AerSimulator is good choice.

[kevinsung]

In qiskit-ibm-runtime 0.22, there will be a "local testing mode". So if we add SamplerV2 here in Aer, it seems there will be two ways to do the same thing:

• Use SamplerV2 from Aer
• Use SamplerV2 from qiskit-ibm-runtime, with an Aer backend.

In general, should we recommend one over the other? I'm thinking from a documentation perspective.

[kevinsung]

Ah, one difference I noticed is that EstimatorV2 might support approximation=True to get a result without statistical sampling error.

[kielpins-qctrl]

@ikkoham

But, there are no advantages for SamplerV2 because simulator specific improvement does not exist.

I primarily use Aer as a way to test code for circuit design before deploying to QPUs. Since the recent changes in qiskit-ibm-runtime behaviour, I must use SamplerV2 on IBM QPUs in order to retrieve bitstrings. Analysis of the results requires a consistent interface, so without SamplerV2 and its associated Result format, Aer is not usable for me.

[garrison]

I primarily use Aer as a way to test code for circuit design before deploying to QPUs. Since the recent changes in qiskit-ibm-runtime behaviour, I must use SamplerV2 on IBM QPUs in order to retrieve bitstrings.

You might want to look at the guide to using SamplerV2 from qiskit-ibm-runtime in local mode, with AerSimulator as backend, after upgrading to qiskit-ibm-runtime 0.22.0 or later: https://docs.quantum.ibm.com/api/migration-guides/local-simulators#aersimulator

[kielpins-qctrl]

@garrison Thanks for flagging this. I was able to successfully run that migration guide. However, the circuit metadata is still absent from the result object, in the same way that I reported for fake backends. Due to this inconsistency with results from real QPUs, I'm no longer able to mock QPU runs with AerSimulator for testing.

[ikkoham]

EstimatorV2 here #2088