2016/12/30 by Rajesh Dutta, Dutta, Rajesh, Kaushik Bagchi +3
Chemistry · Physics and Astronomy · #FOS: Physical sciences #Molecular spectroscopy and chirality #Quantum Physics (quant-ph) #Quantum optics and atomic interactions #Spectroscopy and Quantum Chemical Studies #Statistical Mechanics (cond-mat.stat-mech)
paper · pdf · doi:10.48550/arxiv.1612.09409
openalex publication_date 2016/12/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We address the effects of quantum coherences on the optical line shape of an\nexciton in the presence of dynamic disorder. We consider a one-dimensional\nexcitonic system that consists of two levels placed at regular intervals.\nDetailed analytical calculations of line shape have been carried out by using\nKubo's stochastic Liouville equation (K-QSLE). We make use of the observation\nthat in the site representation, the Hamiltonian of our system with constant\noff-diagonal coupling J is a tridiagonal Toeplitz matrix (TDTM) whose\neigenvalues and eigen functions are known analytically. This identification is\nparticularly useful for long chains where the eigen values of TDTM help to\nunderstand crossover between static and fast modulation limits. We summarize\nthe new results as follows. (i) In the slow modulation limit when the bath\ncorrelation time is large, the effects of spatial correlation are not\nnegligible. Here the line shape is broadened and the number of peak increases\nbeyond the ones obtained from TDTM (constant off-diagonal coupling element J\nand no fluctuation). (ii) However, in the fast modulation limit when the bath\ncorrelation time is small, the spatial correlation is less important (iii)\nImportantly, we find that the line shape can capture that quantum coherence\naffects in the two limits differently.\n