Hello,

I have a Gaussian QNode collection `experiment()`

returning the mean and variance of a displaced squeezed state with an encoded phase. The parameters of the squeezing and displacement gates are in `probe_state_params`

Then the `probs()`

function takes the mean and variance returned by the QNode

`mu_x, sigma_x = experiment(probe_state_params, encoded_phase)`

and returns the gaussian probability distribution created with the mean and variance.

Now I need to find the derivative of the probability distribution w.r.t the encoded_phase. So I’m using parameter shift rule for that.

```
shift = np.pi / 2
plus = probs(probe_state_params, encoded_phase + shift)
minus = probs(probe_state_params, encoded_phase - shift)
dp = (0.5 * (plus - minus))
```

However, when I’m pretty sure the derivative I have computed is incorrect. Am I using the parameter shift rule correctly?

All the `probe_state_params`

and `encoded_phase`

have an inital value assigned.

Thank you in advance

- Kannan