% Superposition of number states (Sec. II.B)
%   |psi> = (1/sqrt(3))|2> + (1/sqrt(2))|5> - (1/sqrt(6))|6>
% Any superposition of number states is a linear combination of identity
% columns; d must exceed the largest number state present.

clear;          % Clear memory
clc;            % Clear the command window/screen
d = 7;          % dimension of the field
I = eye(d);     % Identity matrix of dimension d
Ket2 = I(:,3);  % two-photon state |2>
Ket5 = I(:,6);  % five-photon state |5>
Ket6 = I(:,7);  % six-photon state |6>
Psi = 1/sqrt(3)*Ket2 + 1/sqrt(2)*Ket5 - 1/sqrt(6)*Ket6   % superposition state
N_psi = norm(Psi)                                        % norm of the state Psi