Pulse propagation, population transfer and light storage in five-level media

TL;DR

This paper explores adiabatic interactions in five-level atomic systems with four laser pulses, demonstrating that such systems can replicate three-level media effects like population transfer and light storage, with the added benefit of storing multiple pulses sequentially.

Contribution

It derives analytical eigenvalues for five-level systems and shows they can emulate three-level media effects, enabling sequential light storage.

Findings

Analytical expressions for eigenvalues of five-level systems.

Conditions under which five-level media mimic three-level effects.

Ability to store multiple pulses sequentially in the same medium.

Abstract

We consider adiabatic interaction of five-level atomic systems and their media with four short laser pulses under the condition of all two-photon detunings being zero. We derive analytical expressions for eigenvalues of the system's Hamiltonian and determine conditions of adiabaticity for both the atom and the medium. We analyse, in detail, the system's behaviour when the eigenvalue with non-vanishing energy is realized. As distinct from the usual dark state of a five-level system (corresponding to zero eigenvalue), which is a superposition of three states, in our case the superposition of four states does work. This seemingly unfavourable case is nevertheless demonstrated to imitate completely a three-level system not only for a single atom but also in the medium, since the propagation equations are also split into those for three- and two-level media separately. We show that, under certain conditions, all the coherent effects observed in three-level media, such as population transfer, light slowing, light storage, and so on, may efficiently be realized in five-level media. This has an important advantage that the light storage can be performed twice in the same medium, i.e., the second pulse can be stored without retrieving the first one, and then the two pulses can be retrieved in any desired sequence.