Unknown behavior

[rochisha.a...@gmail.com]

While testing qutip-jax, I noticed, while running the below line in qutip-v5 I get fidelity = 2, which is strange as fidelity is between 0 and 1. Is some new definition of fidelity is being used for this case? Or is this not supported?

Thanks,
Rochisha

qutip.metrics.fidelity(qutip.qeye(2), qutip.qeye(2))

[Simon Cross]

`qutip.qeye(...)` is not a valid density matrix -- it is not normalized and has a trace of 2 instead of 1. Use `.unit()` to normalize it, e.g.:

```

>>> x = qutip.qeye(2).unit()
>>> qutip.metrics.fidelity(x, x)
1.0

```