dq.momentum

momentum(dim: int, *, layout: Layout | None = None) -> QArray

Returns the momentum operator \(p = i (a^\dag - a) / 2\).

Parameters:

• dim –

  Dimension of the Hilbert space.

• layout –

  Matrix layout (dq.dense, dq.dia or None).

Returns:

• (qarray of shape (dim, dim)) –

  Momentum operator.

Examples:

>>> dq.momentum(3)
QArray: shape=(3, 3), dims=(3,), dtype=complex64, layout=dia, ndiags=2
[[  ⋅       0.-0.5j     ⋅      ]
 [0.+0.5j     ⋅       0.-0.707j]
 [  ⋅       0.+0.707j   ⋅      ]]