T2 unittest seems to work incorrectly

[nkanazawa1989]

Informations

• Qiskit Experiments version:
• Python version:
• Operating system:

What is the current behavior?

T2 experiment accept osc_freq in units of "Hz". In the unittest, it accepts a constant frequency value over different time unit prefactors, however, it correctly estimates frequency value.

https://github.com/Qiskit/qiskit-experiments/blob/2d412864c9609bbd0888dbfc9c58eec26796fad8/test/test_t2ramsey.py#L163-L170

In this configuration, frequency is 0.1 Hz, according to the API documentation. Note that it is likely impossible to estimate this frequency with Ramsey delay scan in the window of 45 ns or 45 us (due to too short sampling window), and 45 sec (due to Nyquist frequency).

This may indicate T2Backend incorrectly scales frequency value in it.

Steps to reproduce the problem

What is the expected behavior?

Suggested solutions

[yaelbh]

May be related to #314

[merav-aharoni]

@nkanazawa1989 , I am not sure I understand what you are saying. The osc_freq is input in Hz and output in Hz. In the tutorial for example, it is initialized to 10^5 Hz. In the CI tests, it is initialized to 0.1, but then scaled according to the unit given, for example if unit = ms then the osc_freq is scaled by 10^3 (kiloHz).
Are you saying there is a mistake in the computation, or that the units are not clear from the documentation?

[nkanazawa1989]

then the osc_freq is scaled by 10^3 (kiloHz)

I think this is kind of unexpected behavior. There is no reason to scale frequency with time. If frequency is 0.1 Hz, this should be 0.1 Hz regardless of time unit.

[yaelbh]

@merav-aharoni @nkanazawa1989 What's the current status of this issue?

[nkanazawa1989]

Will be fixed in #427

[yaelbh]

@nkanazawa1989

Will be fixed in #427

Since #427 has been merged, can we close this issue?