Calculate the standard deviation $\sigma = \sqrt{\langle\hat{O}^2 \rangle - \langle\hat{O} \rangle ^2}$ of an operator $\hat{O}$.


Inputs
- $\hat{O}$: Operator - the operator to calculate the standard deviation of
- $\psi$: state - the state the system is in when we want the standard deviation.
Outputs
- Scalar: real number - the calculated standard deviation.
Content
For convenience, the node displays its result directly.