dq.ground

ground() -> QArray

Returns the eigenvector with eigenvalue \(-1\) of the Pauli \(\sigma_z\) operator.

It is defined by \(\ket{g} = \begin{pmatrix}0\\1\end{pmatrix}\).

Note

This function is named ground because \(\ket{g}\) is the lower energy state of a two-level system with Hamiltonian \(H=\omega \sigma_z\).

Returns:

• (qarray of shape (2, 1)) –

  Ket \(\ket{g}\).

Examples:

>>> dq.ground()
QArray: shape=(2, 1), dims=(2,), dtype=complex64, layout=dense
[[0.+0.j]
 [1.+0.j]]