Spectral diffusion induced by sudden jump processes

Игорь Сергеевич Осадько

Игорь Сергеевич Осадько

A dynamic theory of two-photon correlators for a single impurity center developed recently by the author [I. S. Osad’ko, Zh. Éksp. Teor. Fiz. 113 , 1606 (1998) [JETP 86 , 875 (1998)] has been generalized to the case in which the center interacts with nonequilibrium two-level systems (TLSs) in polymers and glasses. Quantum tunneling transitions in TLS manifest themselves as random jumps of a spectral line of an impurity center. These jumps can be either spontaneous or light-induced. Interaction between the impurity center and many nonequilibrium TLSs, which exist in polymers, results in a time dependence of the optical dephasing rate 1/ T 2 of an impurity molecule, i.e., in spectral diffusion. This paper describes how the jumps of the spectral line manifest themselves in the two-photon correlator, which can be measured in experiments.

R. Boscaino, F. M. Gelardi, Rosario N. Mantegna

Aymeric Delteil, Stéphanie Buil, Jean‐Pierre Hermier

Solid-state quantum emitters often suffer from temporal variations of their transition energies, inherited from fluctuations in the host crystal environment. This spectral diffusion (SD) is detrimental to the emitter linewidth but is often challenging to characterize experimentally. The authors show here that, under resonant laser excitation, the statistics of the scattered photons offer multiple signatures of the SD process, making it possible to discriminate between discrete jumps and continuous diffusion, as well as to access relevant parameters of the SD mechanisms.

Italo Guarneri

František Šanda, Shaul Mukamel

Signatures of chemical exchange and spectral diffusion in 2D photon-echo line shapes of molecular aggregates are studied using model calculations for a dimer whose Hamiltonian parameters are stochastically modulated. Cross peaks induced by chemical exchange and by exciton transport have different dynamics and distinguish two models which have the same absorption spectrum (a two-state jump bath modulation model of a dimer and a four-state jump bath model of a single chromophore). Slow Gaussian-Markovian spectral diffusion of a symmetric dimer induces new peaks which are damped as the dipole moment is equilibrated. These effects require an explicit treatment of the bath and may not be described by lower-level theories such as the Redfield equations, which eliminate the bath.