Test failure: test_noise

[cqc-alec]

Recently test_noise (in backend_test.py) has started to fail, with the following error:

FAILED backend_test.py::test_noise - assert np.float64(0.0) > np.float64(0.46)

(I can't see any code changes that could have caused this, so it may be something to do with the noise model being reported by the backend?)

[cqc-alec]

If I use a different backend (torino) instead of brisbane, the test passes, so I suspect we are receiving a corrupted error model ...

[cqc-alec]

Or the error model may not be corrupted, we may just be selecting qubits with very high qubit readout error rates. Ideally we would not do that ...

[cqc-alec]

Yes, it seems we are selecting dud qubits for the placement.

[cqc-alec]

This test is passing again, because the qubits on brisbane are back. I'm going to close this as I think the issue was with the backend, but we should perhaps think about how such issues could be detected.