Spontaneous emission from the bare ground state of an optically driven three-level atom: Perturbation theory and energy conservation
J. L. Cohen, P. R. Berman
We present a perturbative derivation of the fluorescence spectrum for a three-level atom driven by a classical radiation field. The energies of the three atomic levels are equal to \ensuremath{\Elzxh}${\mathrm{\ensuremath{\omega}}}_{\mathrm{i}}$ (i=1, 2, and 3) with ${\mathrm{\ensuremath{\omega}}}_{3}$\ensuremath{\gtrsim}${\mathrm{\ensuremath{\omega}}}_{2}$\ensuremath{\gtrsim}${\mathrm{\ensuremath{\omega}}}_{1}$ and ${\mathrm{\ensuremath{\omega}}}_{32}$\ensuremath{\gg}${\mathrm{\ensuremath{\omega}}}_{21}$ (${\mathrm{\ensuremath{\omega}}}_{\mathit{ij}}$=${\mathrm{\ensuremath{\omega}}}_{\mathit{i}}$-${\mathrm{\ensuremath{\omega}}}_{\mathit{j}}$). The radiation field, having a frequency \ensuremath{\Omega}\ensuremath{\gtrsim}${\mathrm{\ensuremath{\omega}}}_{31}$, can be considered to drive the 2-3 transition only. Spontaneous emission from the ground state, via a normally counter-rotating atom-vacuum interaction term in the Hamiltonian, conserves energy when a photon is subsequently absorbed from the laser field. The spectrum is explained in terms of a Raman process, and in terms of an interaction between the laser field and the coupled atom-vacuum field system. Connection is made with a dressed-atom description of the problem. \textcopyright{} 1996 The American Physical Society.
Physical Review A•Aug 1, 1996•3 citations