Theory of resonance fluorescence in

In cartesian coordinates it may be shown (Problem 15.5) that the polarization vector of the incident radiation is given by 

For the evaluation of the atomic matrix elements, however, it is more convenient to expand 8 in terms of the spherical unit vectors = + - (l i2) form given by 

The electric dipole moment operator, D, may be expanded in the same manner and it can tlien be shown that 

We must now evaluate the matrix elements of the electric dipole operator. We choose as an example a system in 

The de-excitation matrix for light emitted in the direction (6, (() ) and linearly polarized parallel to the electric vector e is defined by 

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Introduction and experimental technique. The classical theory of resonance fluorescence, in which the atoms are treated as dipole oscillators processing at the Larmor frequency, leads one to predict that interesting effects will also occur if the atoms are excited by light whose intensity is periodically modulated. As the external magnetic field is varied in these experiments a point is reached at which the Larmor frequency, equals the angu-... 

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