


function spin_half_matrices()
	s_SP = Array{Float64, 2}([0 0; 1 0])
	s_SM = Array{Float64, 2}([0 1; 0 0])
	s_Z = Array{Float64, 2}([-1 0; 0 1])
	s_x = s_SP+s_SM
	s_y = -im*(s_SP-s_SM)
	return Dict("x"=>s_x, "y"=>s_y, "z"=>s_Z, "+"=>s_SP, "-"=>s_SM)
end
