In the simulation of Pauli error or Depolarizing error (here is an example for BitFlip Channel in Pennylane), if the parameter p represents the probability of PauliX-error, its corresponding Kraus Operator is not \sqrt{p}X, but \sqrt{p+\varepsilon}X, like this:

```
K0 = np.sqrt(1 - p + np.eps) * np.eye(2)
K1 = np.sqrt(p + np.eps) * np.array([[0, 1], [1, 0]]
```

My questions are:

- Why use this \varepsilon for the simulation of the quantum error channel ? (I mean that \varepsilon may lead to an imperfect error channel.)
- And what is the specific setting for \varepsilon? (This question is equally important for me )

Love you guys