[WIP] Resonator spectroscopy

[eggerdj]

Summary

This PR introduce an experiment to do resonator spectroscopy.

Details and comments

Resonator spectroscopy is done by sweeping the frequency of a pulse applied to the readout resonator. Since no discriminator is available (we don't even know the frequency of the resonator when doing this experiment) IQ data must be used. Furthermore, the IQ data may rotate in the IQ plane depending on the frequency of the readout pulse. Therefore, the standard SVD node cannot process the data and the ToAbs node is introduced.

• Tests
• Encapsulate into a circuit
• Align with Curve Analysis class #46
• Align with Generalize spectroscopy #82

[yaelbh]

@eggerdj Do you intend to complete this PR ?

There has been some discussion around #387. @jyu00 prefers to merge #387 only after #90 is done. Do you agree? @nkanazawa1989 What do you think?

[eggerdj]

@yaelbh Yes, I intend to complete this PR. Currently it is still blocked since pulse gates do not play nicely with acquire instructions. As far as I understand Lauren has been actively working on the pulse gate and acquire issue.

[lcapelluto]

This is so nice -- just by skimming the PR and cloning qiskit_experiments I was able to create a ResonatorSpectroscopy class to grab circuits, (added 3 lines to create circuits rather than schedules) and used that to create test cases on the backend side! 😄

fyi these were my changes

            with pulse.build(backend=backend, name="spectroscopy") as meas_cal:
                ...

            circuit = QuantumCircuit(1, 1)
            circuit.measure(qubit, qubit)
            circuit.add_calibration('measure', [qubit], block_to_schedule(meas_cal))

            ...
            circuits.append(circuit)

(probably needs to be QuantumCircuit(qubit, qubit), or something to avoid out of bounds errors)

[eggerdj]

@lcapelluto yes the PR was originally written with schedules due to the pulse gate issue. The changes you suggest are the way to go.

[wshanks]

Should this be closed now that there is #583?

[eggerdj]

Replaced by #583