# gamma

### gamma(mode, is_prime)

Create a majorana fermion.

For a given mode `i`, two majorana fermions can be created:
: - `gamma(i, False)` creates $\gamma = a_i^\dagger + a_i$
  - `gamma(i, True)` creates $\gamma' = i(a_i^\dagger - a_i)$

The argument order is `(mode, is_prime)` to reflect the natural interpretation of
majorana operators: first specify the mode, then the variant. Unlike fermionic operators –
where the distinction between creation and annihilation is fundamental – the two majorana
variants are more symmetric and conceptually less different.

This mirrors the normal-ordering convention for majoranas, where operators are sorted first by
mode and then by variant. For example, a normally ordered string like
`((1, True), (0, False), (0, True)` is more readable and intuitive than
`((True, 1), (False, 0), (True, 0)`.

* **Parameters:**
  * **mode** ([*int*](https://docs.python.org/3/builtins/functions.html#int)) – index of the fermionic mode.
  * **is_prime** ([*bool*](https://docs.python.org/3/builtins/functions.html#bool)) – whether to create $\gamma$ (False) or $\gamma'$ (True).
* **Returns:**
  A `MajoranaAction` object, which is essentially the flat index `2*mode+int(is_prime)`.
* **Return type:**
  [int](https://docs.python.org/3/builtins/functions.html#int)