Distinctive character of electronic and vibrational coherences in disordered molecular aggregates

Coherent dynamics of coupled molecules are effectively characterized by the two-dimensional (2D) electronic coherent spectroscopy. Depending on the coupling between electronic and vibrational states, oscillating signals of purely electronic, purely vibrational or mixed origin can be observed. Even in the "mixed" molecular systems two types of coherent beats having either electronic or vibrational character can be distinguished by analyzing oscillation Fourier maps, constructed from time-resolved 2D spectra. The amplitude of the beatings with the electronic character is heavily affected by the energetic disorder and consequently electronic coherences are quickly dephased. Beatings with the vibrational character depend weakly on the disorder, assuring their long-time survival. We show that detailed modeling of 2D spectroscopy signals of molecular aggregates providesdirect information on the origin of the coherent beatings.Comment: 7 pages, 4 figures, 1 tabl

Qadence: a differentiable interface for digital-analog programs

Digital-analog quantum computing (DAQC) is an alternative paradigm for universal quantum computation combining digital single-qubit gates with global analog operations acting on a register of interacting qubits. Currently, no available open-source software is tailored to express, differentiate, and execute programs within the DAQC paradigm. In this work, we address this shortfall by presenting Qadence, a high-level programming interface for building complex digital-analog quantum programs developed at Pasqal. Thanks to its flexible interface, native differentiability, and focus on real-device execution, Qadence aims at advancing research on variational quantum algorithms built for native DAQC platforms such as Rydberg atom arrays

Nonclassical energy transfer in photosynthetic FMO complex

Excitation energy transfer in a photosynthetic FMO complex has been simulated using the stochastic Schrödinger equation. Fluctuating chromophore transition energies are simulated from the quantum correlation function which allows to properly include the finite temperature. The resulting excitation dynamics shows fast thermalization of chromophore occupations into proper thermal equilibrium. The relaxation process is characterized by entropy dynamics, which shows nonclassical behavior

Phase relationships of spectral oscillations in 2D molecular spectroscopy

Spectral oscillations in 2D molecular spectroscopy of the displaced oscillator system and their phase relationships are analyzed. The phase maps of the dispersive and absolute-valued signals give hints for experimental probing of peak oscillations

Vibrational vs. electronic coherences in 2D spectrum of molecular systems

Two-dimensional spectroscopy has recently revealed the oscillatory behavior of the excitation dynamics of molecular systems. However, in the majority of cases there is considerable debate over what is actually being observed: excitonic or vibrational wavepacket motion or evidence of quantum transport. In this letter we present a method for distinguishing between vibrational and excitonic wavepacket motion, based on the phase and amplitude relationships of oscillations of distinct peaks as revealed through a fundamental analysis of the two-dimensional spectra of two representative systems. (C) 2012 Elsevier B.V. All rights reserved

Phase relationships of spectral oscillations in 2D molecular spectroscopy

Spectral oscillations in 2D molecular spectroscopy of the displaced oscillator system and their phase relationships are analyzed. The phase maps of the dispersive and absolute-valued signals give hints for experimental probing of peak oscillations

Multistep Photoluminescence Decay Reveals Dissociation of Geminate Charge Pairs in Organolead Trihalide Perovskites

Charge carrier dynamics in organolead iodide perovskites is analyzed by employing time-resolved photoluminescence spectroscopy with several ps time resolution. The measurements performed by varying photoexcitation intensity over five orders of magnitude enable separation of photoluminescence components related to geminate and nongeminate charge carrier recombination and to address the dynamics of an isolated geminate electronhole pair. Geminate recombination dominates at low excitation fluence and determines the initial photoluminescence decay. This decay component is remarkably independent of the material structure and experimental conditions. It is demonstrated that dependences of the geminate and nongeminate radiative recombination components on excitation intensity, repetition rate, and temperature, are hardly compatible with carrier trapping and exciton dissociation models. On the basis of semiclassical and quantum mechanical numerical calculation results, it is argued that the fast photoluminescence decay originates from gradual spatial separation of photogenerated weakly bound geminate charge pairs