Strong Enhancement of the Lifetime of a Resonance State by Using a Combination of Two Laser Pulses

Abstract

The lifetime of a resonance state overlapping with a second resonance is shown to be strongly enhanced (by a factor of 3) by combining two pump pulses to simultaneously excite the two resonances. Such an enhancement is produced by interference effects occurring between the two coherently excited overlapping resonances. A high degree of control on the intensity of interference, and thus on the resonance lifetime enhancement, is found to be achieved by varying the delay time between the pulses and their relative intensities.

Selective coherent control of the lifetime of a resonance state with laser pulses

“…As previously discussed, 31,33 for Br 2 (B, v = 27)−Ne the two pulse electric field creates a superposition of essentially two v and v − 1 overlapping resonances (t) = a gr (t)ψ gr (t) + a n (t)ψ n (t).…”

“…It has been found 33 that the delay time between pulses is a parameter that affects dramatically the degree of control achieved on the resonance lifetime, and that can be optimized for each target resonance. It is stressed, however, that in the present work no attempt has been made to optimize the delay time between pulses chosen.…”

“…By varying the ratio of intensities and the delay time between the two pulses, a strong enhancement of the resonance lifetime, by a factor of up to three, was achieved. 33 The regime of two overlapping resonances of Br 2 (B, v = 27)−Ne is the simplest overlapping regime we can have, being very suitable to understand how the proposed control scheme works. 31 The counterpart, however, is that this sparse overlapping regime limits to a large extent the possibilities of control of the scheme.…”

“…It is stressed that the v ground resonance survival probability and the Br 2 (B, v < v ) appearance probabilities are observable quantities. 38,40 However, the more flexible control scheme using two pulses 33 (or even more) is expected to exploit better the new possibilities for control that appear with the denser overlapping regime. One of these possibilities is to select different v − 1 overlapping resonances to be excited with the second pump laser pulse, which will probably lead to a different pattern of interference with the v ground resonance, and to a correspondingly different degree of control.…”

Communication: Control of the fragment state distributions produced upon decay of an isolated resonance state

“…Thus, exerting control over these two properties of the resonance decay would provide a high degree of control on the process mediated by the resonance of interest. Schemes to control the lifetime of a single resonance state have been developed for the cases of both overlapping 18,19 and isolated resonances. 20 Control strategies have also been proposed to modify the product fragment state distributions produced by the decay of a superposition of resonances.…”