Observation and quantification of the quantum dynamics of a strong-field excited multi-level system

Abstract

The quantum dynamics of a V-type three-level system, whose two resonances are first excited by a weak probe pulse and subsequently modified by another strong one, is studied. The quantum dynamics of the multi-level system is closely related to the absorption spectrum of the transmitted probe pulse and its modification manifests itself as a modulation of the absorption line shape. Applying the dipole-control model, the modulation induced by the second strong pulse to the system’s dynamics is quantified by eight intensity-dependent parameters, describing the self and inter-state contributions. The present study opens the route to control the quantum dynamics of multi-level systems and to quantify the quantum-control process.

Transient-absorption phases with strong probe and pump pulses

“…For the noncollinear geometry depicted in Fig. 2, fast oscillations of the measured transient-absorption spectrum as a function of time delay τ cannot be distinguished and are averaged out [26,27]. Here, this is taken into account by convolving S 1 (ω, τ ) with a normalized Gaussian function G(τ, ∆τ ) of width ∆τ = 5 × 2π/ω L , which leads to…”

“…The attention is thus focused on the characterization of the action of the pump pulse as a function of its parameters such as, e.g., intensity and laser frequency, and the main line-shape modifications are exclusively attributed to its nonlinear interaction with the system. Recent investigations of transient-absorption spectra in Rb atoms were based on this assumption [26,27].…”

“…Related line-shape-manipulation experiments in gaseous rubidium have recently shown how this line-shape-control concept can be applied to more complex multilevel systems [35,36] and used to understand their quantum dynamics. Femtosecond optical pump and probe pulses were used to excite the V-type three-level system formed by the  s S p P 5 5 (780.03 nm) transitions, for a pump-probe and probe-pump setup and for different time delays.…”

Ultrafast dynamic evolution of multilevel systems in medium-strength laser fields

“…Recently, it was demonstrated that the phase of a sample's polarization induced by a resonant laser field in an atomic system can be modified by a strong nonresonant laser field owing to the AC Stark effect [17][18][19][20]. This model is known as the dipole phase control theory and has been extended to multilevel and complex molecular systems by using medium-strength pump and weak probe pulses with the same frequency [21][22][23]. Actually, both the phase and amplitude of a sample's response in the time domain will be significantly modified by the AC stark effect and Rabi oscillation, respectively, regardless of whether the probe pulse precedes or follows the pump pulse.…”

Light-induced states in the transient-absorption spectrum of a periodically pumped strong-field-excited system

“…If the duration of the probe pulse is comparable with that of the pump pulse, the absorption spectra do not provide the resolution necessary to access the real-time dynamics taking place during the pump pulse. This is for example the case when optical transitions have to be studied or controlled with optical femtosecond pump and probe pulses of equal duration [21][22][23][24]. The Rabi oscillations responsible for the appearance of LISs take place only within the pump pulse, and a probe pulse of equal duration does not have the required resolution to distinguish them.…”