Quantum interference control of a four-level diamond-configuration quantum system

Abstract

We investigate coherent control of the two-photon transition pathways of a four-level atomic system in a diamond configuration. When an ultrashort laser pulse interacts with this system in the ground state 5S 1/2 of rubidium, the two-photon transition probability amplitude of 5D 3/2 is obtained by a summation of all possible resonant and nonresonant two-photon transition probability amplitudes via 5P 1/2 and 5P 3/2. Second-order perturbation theory predicts that the maximal constructive interference of the transition probability amplitudes occurs when the phases of eight different spectrum blocks satisfy four different phase relations. Experiments carried out with spectrally phase-coded laser pulses show good agreement with the theoretical prediction.

Quantum control and pathway manipulation in rubidium

“…Assuming that all amplitudes (A k ) have approximately the same magnitude, then the following results can be derived by keeping only the largest (U 13 13 and U 24 24 ) and second largest terms (U 13 11 , U 13 31 , U 24 13 and U 24 23 )…”

“…Due to the fact that ω 4 − ω 3 ≫ ω 3 − ω 1 , the second largest terms of U 2 (t) (U 24 13 and U 24 23 ) have much smaller magnitude than those of U 1 (t) (U 13 11 and U 13 31 ), which leads to…”

“…These field parameters were chosen to approach the experimental conditions in Ref. [24]. In our simulations, E 0 is taken to be 0.0006 (a.u.…”

“…Stowe et al adopted a similar strategy (i.e., changing the phase of a spectral window) to achieve coherent control of atomic Rb, where the contributions of both Rb pathways (5S 1/2 →5P 3/2 →5D 3/2 and 5S 1/2 →5P 1/2 →5D 3/2 ) are considered due to much wider bandwidth of the pulse [23]. Recently, Lee et al have proposed another similar scheme to simultaneously control the two pathways by manipulating the phase of eight spectral blocks for maximizing the constructive interference between the two pathways [24]. However, only the total TPA signal corresponding to the final population transferred to the Rb state 5D 3/2 was investigated in the above works, and the prospect of manipulating the pathway amplitudes themselves was not discussed.…”

Amplified spontaneous emission at 523 μm in two-photon excited rubidium vapor

“…This is largely because of the difficulty of detecting the mid-IR radiation, which is strongly absorbed in conventional Rb cells. We note that similar energy level configurations in Rb atoms have been used extensively for studying ladder-type electromagnetically induced transparency [15,16], nonlinear properties of four-wave mixing and new field generation [17,18], atomic coherence effects [19,20] and transfer of orbital angular momentum [3,21], as well as for imaging of ultracold atoms [22].…”