Pulse area dependence of multiple quantum coherence signals in dilute thermal gases

Ames, Benedikt; Buchleitner, Andreas; Carnio, Edoardo G.; Shatokhin, Vyacheslav

doi:10.1063/5.0053673

Cited by 4 publications

(7 citation statements)

References 39 publications

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“…The initial density operator (0) of the atom-field system factorises into the ground state of the atoms and the vacuum state of the field. The positive frequency part E (+) k (t) of the operator for the electric far-field can be expressed through the atomic lowering operator of the source atoms [41,42], 6…”

Section: Fluorescence Intensitymentioning

confidence: 99%

“…Thus, an arbitrary time-dependent atomic dipole correlator can be obtained from the quantum master equation [42,43] (written in the interaction picture with respect to the free-atom Hamiltonian H 0 ) 8 :…”

Section: Master Equationmentioning

confidence: 99%

“…L the laser-atom interaction Liouvillian; L γ = N α=1 L α γ , with L α γ the Lindblad superoperator describing the atomic relaxation due to the electromagnetic bath; and L int = N α =β=1 L αβ , with L αβ the Liouvillian describing the dipole-dipole interactions mediated by the (common) electromagnetic bath. The Liouvillians read [24,25,33,42]…”

Section: Master Equationmentioning

confidence: 99%

“…Strong pulses (e.g., ϑ ≈ π) induce a nonlinear response of the atoms [19,53] and can be used as a control and diagnostic tool in electronic spectroscopy [54,55]. Furthermore, we have shown that strong pulses substantially modify the MQC signals [42]. However, in our present contribution we seek to elucidate the impact of the dipolar interactions on these signals.…”

Section: Ultrashort Time Scale-atom-laser Interactionmentioning

confidence: 99%

“…Unlike the uniform spatial distribution of the atoms, the Doppler shifts Δ α are non-uniformly Maxwell-Boltzmann distributed. Therefore, the result of averaging over Δ α is different from that of averaging over random atomic positions; it would not eliminate the terms including velocity-dependent phases, but instead result in inhomogeneous line broadening [31] of MQC spectra [42]. In our present contribution, we ignore this effect and set the Doppler shifts in equation (30) to zero, while focussing on the general structure and physical origin of the resonances of 1QC and 2QC spectra.…”

Section: Configurational Averagementioning

confidence: 99%

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Theory of multiple quantum coherence signals in dilute thermal gases

et al. 2022

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Manifestations of dipole-dipole interactions in dilute thermal gases are difficult to sense because of strong inhomogeneous broadening. Recentexperiments reported signatures of such interactions in fluorescence detection-based measurements of multiple quantum coherence (MQC) signals, with many characteristic features hitherto unexplained. We develop an original open quantum systems theory of MQC in dilute thermal gases, which allows us to resolve this conundrum. Our theory accounts for the vector character of the atomic dipoles as well as for driving laser pulses of arbitrary strength, includes the far-field coupling between the dipoles, which prevails in dilute ensembles, and effectively incorporates atomic motion via a disorder average. We show that collective decay processes -- which were ignored in previous treatments employing the electrostatic form of dipolar interactions -- play a key role in the emergence of MQC signals.

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Section: Fluorescence Intensitymentioning

confidence: 99%

Section: Master Equationmentioning

confidence: 99%

Section: Master Equationmentioning

confidence: 99%

Section: Ultrashort Time Scale-atom-laser Interactionmentioning

confidence: 99%

Section: Configurational Averagementioning

confidence: 99%

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Theory of multiple quantum coherence signals in dilute thermal gases

et al. 2022

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Equation-of-Motion Methods for the Calculation of Femtosecond Time-Resolved 4-Wave-Mixing and N-Wave-Mixing Signals

2022

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Femtosecond nonlinear spectroscopy is the main tool for the time-resolved detection of photophysical and photochemical processes. Since most systems of chemical interest are rather complex, theoretical support is indispensable for the extraction of the intrinsic system dynamics from the detected spectroscopic responses. There exist two alternative theoretical formalisms for the calculation of spectroscopic signals, the nonlinear response-function (NRF) approach and the spectroscopic equation-of-motion (EOM) approach. In the NRF formalism, the system–field interaction is assumed to be sufficiently weak and is treated in lowest-order perturbation theory for each laser pulse interacting with the sample. The conceptual alternative to the NRF method is the extraction of the spectroscopic signals from the solutions of quantum mechanical, semiclassical, or quasiclassical EOMs which govern the time evolution of the material system interacting with the radiation field of the laser pulses. The NRF formalism and its applications to a broad range of material systems and spectroscopic signals have been comprehensively reviewed in the literature. This article provides a detailed review of the suite of EOM methods, including applications to 4-wave-mixing and N-wave-mixing signals detected with weak or strong fields. Under certain circumstances, the spectroscopic EOM methods may be more efficient than the NRF method for the computation of various nonlinear spectroscopic signals.

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