Consider two EM waves detuned from an atomic transition F g = 1 → → F e = 2 with equal amplitudes: E 1 → → = E 0 e i k z − − x ^ ^ − − i y ^ ^ 2 and E 2 → → = E 0 e − − i k z x ^ ^ − − i y ^ ^ 2 . The superposition of these two waves is: