报告时间：6月23日 周五 下午3:00
报告题目： Spectroscopy of Molecular Aggregates & Many-body Decoherence
报告摘要：Nature has mastered the art of molecular self-assembly, evolving from a very limited number of building blocks an impressive diversity of photosynthetic light-harvesting complexes, which are highly versatile and efficient. Understanding the sensitive interplay between the self-assembled superstructures and their functional properties is highly desirable for the synthesis of new materials, the design and operation of organic-based devices. In a first part, I will focus on dynamical properties of the photosyntetic aggregates, modeled as open quantum systems and  propose a theory explaining the origins of long-lived coherences observed in their 2D electronic spectra,  show the influence of excitation conditions on the open dynamics and [3-5] present how to mimic natural excitation in the lab, i.e. how incoherent sunlight relates to coherent laser pulses. This relies on a new formalism, based on thermally excited wave packets, that provides the missing link for a continuous connection between classical and quantum representations of a thermal gas .
In a second part, I will turn to equilibrium and spectral properties, and present a systematic method that establishes a relationship between molecular superstructures and their optical and transport properties . This model allows one to predict the physical properties of complex structures and, conversely, infer the structure from its measured properties. In addition, it provides a practical method to compute spectra and transfer rates in multichromophoric systems from experimentally accessible monomer data.
In a last part, I will introduce a scheme for the quantum simulation of many-body decoherence, which is based on the unitary evolution of a stochastic Hamiltonian . I will show how to simulate an effectively open dynamics governed by k-body Lindblad operator, following Markovian or non-Markovian dynamics, and provide the time scale governing the fidelity decay. Such scheme exhibits a strong signature of many-body decoherence, and can be readily implemented in current quantum platforms.
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