% Pauli operators and Hamiltonian for a two-level atom (Sec. III.C)
%   H = (hbar*omega_0/2) sigma_z
% sigma_+ raises (|g> -> |e>) and sigma_- lowers (|e> -> |g>).

clear;          % Clear memory
clc;            % Clear the command window/screen
hbar = 1;
Omega_0 = 1;            % atomic transition frequency
Sz = [1 0; 0 -1]        % sigma_z operator
Splus = [0 1; 0 0]      % raising operator sigma_+
Sminus = [0 0; 1 0]     % lowering operator sigma_-
H = hbar*Omega_0/2*Sz   % Hamiltonian for a two-level atom