_sparse_tools.py 文件源码

def jw_number_restrict_operator(operator, n_electrons, n_qubits=None):
    """Restrict a Jordan-Wigner encoded operator to a given particle number

    Args:
        sparse_operator(ndarray or sparse): Numpy operator acting on
            the space of n_qubits.
        n_electrons(int): Number of particles to restrict the operator to
        n_qubits(int): Number of qubits defining the total state

    Returns:
        new_operator(ndarray or sparse): Numpy operator restricted to
            acting on states with the same particle number.
    """
    if n_qubits is None:
        n_qubits = int(numpy.log2(operator.shape[0]))

    select_indices = jw_number_indices(n_electrons, n_qubits)
    return operator[numpy.ix_(select_indices, select_indices)]