scqubits.Cos2PhiQubit.n_2_operator

Cos2PhiQubit.n_2_operator(energy_esys=False)

Returns operator representing the charge difference across junction 2 in native or eigenenergy basis.

Parameters:

energy_esys (Union[bool, Tuple[ndarray, ndarray]]) – If False (default), returns operator in the harmonic oscillator basis. If True, the energy eigenspectrum is computed, returns operator in the energy eigenbasis. If energy_esys = esys, where esys is a tuple containing two ndarrays (eigenvalues and energy eigenvectors), returns operator in the energy eigenbasis, and does not have to recalculate eigenspectrum.

Return type:

Union[ndarray, csc_matrix]

Returns:

Operator in chosen basis. If native basis chosen, operator returned as a csc_matrix. If the eigenenergy basis is chosen, unless energy_esys is specified, operator has dimensions of truncated_dim x truncated_dim, and is returned as an ndarray. Otherwise, if eigenenergy basis is chosen, operator has dimensions of m x m, for m given eigenvectors, and is returned as an ndarray.