Coherent control of spontaneous emission in a four-level system

In this article we study the potential for coherently control spontaneous e mission in a four-level scheme. Our control parameter is the relative phase of two laser fields having the same angular frequency. We investigate in d etail the trapping conditions, the population dynamics and the behaviour of the (long time) spontaneous emission spectrum, which are now phase depende nt. Inhibition of spontaneous emission and extreme spectral narrowing are s hown as the relative phase is varied. Our results are interpreted using a d ressed state analysis of the dynamics.