ResonatorSpectroscopy is incompatible with BackendV2

[tenzan-araki]

Informations

• Qiskit Experiments version: main
• Python version: 3.10.7
• Operating system: Mac OS

What is the current behavior?

ResonatorSpectroscopy fails to obtain center frequency of resonator for BackendV2, because BackendV2 does not have access to BackendData.meas_freqs. Specifically, BackendData(backend).meas_freqs is an empty list, and center_freq = BackendData(backend).meas_freqs[physical_qubits[0]] results in the error list index out of range.

Steps to reproduce the problem

The following code produces the error:

from qiskit_ibm_provider import IBMProvider
from qiskit_experiments.library import ResonatorSpectroscopy

provider = IBMProvider()
backend = provider.get_backend('ibm_hanoi')

qubit = 0
spec = ResonatorSpectroscopy((qubit,), backend)

The following code shows that this is caused by an incompatibility with BackendV2:

from qiskit import IBMQ
from qiskit_ibm_provider import IBMProvider
from qiskit_experiments.framework import BackendData

IBMQ.load_account()
provider1 = IBMQ.get_provider(hub='ibm-q-internal', group='deployed', project='default')
provider2 = IBMProvider(instance="ibm-q-internal/deployed/default")

backendV1 = provider1.get_backend('ibm_hanoi')
backendV2 = provider2.get_backend('ibm_hanoi')

print('BackendV1: ', BackendData(backendV1).meas_freqs)
print('BackendV2: ', BackendData(backendV2).meas_freqs)

What is the expected behavior?

The ResonatorSpectroscopy experiment should be made compatible with BackendV2.

[wshanks]

#900 which I had opened a while ago should fix this. I have just brought it back up to date so it can be reviewed and merged.

[wshanks]

You can get around the error by using absolute=False for now.