We consider spontaneous emission in a four-level atomic system driven by three fields. It is shown that by controlling the phase and the amplitude of the driving fields a wide variety of spectral behavior can be obtained, ranging from a very narrow single spectral line to up to six spectral of varying widths.
We investigate theoretically the features of the spontaneous emission spectrum of a four-level atomic system driven by a coherent probe field,a coupling laser field and a microwave field.The two upper levels are coupled by a microwave field with lower frequency.The time evolution of the populations is calculated.It is shown that the spectra behavior,such as spectral-line narrowing,spectral-line enhancement,spectral-line suppression,and total cancellation of fluorescence quenching,can be easily controlled by changing the phase and the amplitude of the microwave field.
The spontaneous emission property of a five-level atom with a loop structure driven by three optical fields and a microwave field is intensively studied. Several quantum interference effects can be observed in the spontaneous emission spectra, such as spectral-line narrowing, spectral-line enhancement, spectral-line suppression, partial cancellation and fluorescence quenching. The number of emission peaks, the positions of dark lines can be controlled by varying the intensities of driving fields or the phase of the microwave field coupling the two lower levels in the atomic system. Furthermore, since no rigorous conditions are required, the expected phenomena may easily be achieved experimentally in atomic systems.
Control of amplitude and phase of the driving field in an atom-field interaction leads towards the strong line narrowing and quenching in the spontaneous emission spectrum. We exploit this fact for the atom localization scheme and achieve a much better spatial resolution in the conditional position probability distribution of the atom. Most importantly the quenching in the spontaneous emission manifests itself in reducing the periodicity in the conditional position probability distribution and hence the uncertainty in a particular position measurement of the single atom by a factor of 2.