Nontrivial excited-state coherence due to two uncorrelated partially coherent fields

Abstract

We analyze a model where a closed V system is excited by two uncorrelated partially coherent fields. We use a collisionally broadened CW laser, which is a good model for an experimentally realizable partially coherent field, and show that it is possible to generate excited state coherences even if the two fields are uncorrelated. This transient coherence can be increased if splitting between the excited states is reduced relative to the radiation coherence time, τ d . For small excited state splitting, one can use this scheme to generate a long lived coherent response in the system.

Reinvigorating Excited State Coherences in $V$ Level Systems with the use of Trap States

“…To quantify the strength of a coherent response, we use the measure C = |ρ 12 |/(ρ 11 + ρ 22 ) from our previous work [11,12]. This measure elucidates the mixed state nature of the excited state density matrix, which is a sub matrix composed of the excited state populations and the coherences between the excited states.…”

“…This could also represent processes in atomic or molecular physics, whereby excited states decay to lower energy states through relaxation processes or spontaneous emission. It is of interest to know if it is possible to devise a scheme that can rejuvenate the transient coherent response observed in short time regime [11][12][13][14]. In the context of biological lightmatter interaction, for example, if excitation on one site has been dissipated or funneled to another excitation site, is it possible to produce a second transient coherent response by excitation of the initial site?…”