Control excitation and coherent transfer in a dimer

Environmental design principles for efficient excitation energy transfer in dimer and trimer pigment-protein molecular aggregates and the relation to non-Markovianity

In this study, we explore optimal environments for efficient EET between end sites in a number of dimer and trimer model pigment-protein molecular aggregates when the EET dynamics is modeled by the HEOM-method. For these optimal environmental parameters, we further quantify the non-Markovianity by the BLP-measure to elucidate its possible connection to efficient EET. We also quantify coherence in the pigment systems by means of the measure l1-norm of coherence to analyze its interplay with environmental effects when EET efficiency is maximal. Our aim is to investigate possible environmental de…

Attenuation of excitation decay rate due to collective effect

We study a series of $N$ oscillators each coupled to its nearest neighbours, and linearly to a phonon field through the oscillator's number operator. We show that the Hamiltonian of a pair of adjacent oscillators, or a dimer, within the series of oscillators can be transformed to a form in which they are collectively coupled to the phonon field as a composite unit. In the weak coupling and rotating-wave approximation, the system behaves effectively like the trilinear boson model in the one excitation subspace of the dimer subsystem. The reduced dynamics of the one excitation subspace of the di…

Correlation effects and collective excitations in bosonic bilayers: role of quantum statistics, superfluidity and dimerization transition

A two-component two-dimensional (2D) dipolar bosonic system in the bilayer geometry is considered. By performing quantum Monte Carlo simulations in a wide range of layer spacings we analyze in detail the pair correlation functions, the static response function, the kinetic and interaction energies. By reducing the layer spacing we observe a transition from weakly to strongly bound dimer states. The transition is accompanied by the onset of short-range correlations, suppression of the superfluid response, and rotonization of the excitation spectrum. A dispersion law and a dynamic structure fact…

Non-hermitian exciton dynamics in a photosynthetic unit system

The non-hermitian quantum dynamics of excitonic energy transfer in photosynthetic systems is investigated using a dissipative two-level dimer model. The approach is based on the Green's function formalism which permits consideration of decoherence and intersite transfer processes on comparable terms. The results indicate a combination of coherent and incoherent behavior at higher temperatures with the possibility of exceptional points occurring at the coherent-incoherent crossover regime at critical temperatures. When each dimer site is coupled equally to the environmental sources of dissipati…

在超冷原子热气体形成二聚体的过程中观测到相干振荡

Observation of coherent oscillations in association of dimers from a thermal gas of ultracold atoms

本文报告了在超冷原子热气体形成弱束缚二聚体的转化效率中观测到相干振荡，发现通过强调制脉冲诱导的非绝热跃迁可恢复因热能导致的相干性丧失，并得到了理论与数值计算的支持。

使用量子硬件实现高保真二聚体激发

High-fidelity dimer excitations using quantum hardware

针对量子自旋二聚体动力学模拟，提出使用短深度电路的资源高效快进（REFF）方法，在量子硬件上实现高保真长时间尺度模拟并计算动力学结构因子，为预测和基准测试非弹性中子散射实验提供了新途径。

Calculations of Nonlinear Wave-Packet Interferometry Signals in the Pump-Probe Limit as Tests for Vibrational Control over Electronic Excitation Transfer

The preceding paper describes a strategy for externally influencing the course of short-time electronic excitation transfer (EET) in molecular dimers and observing the process by nonlinear wave-packet interferometry (nl-WPI). Within a sample of isotropically oriented dimers having a specified internal geometry, a vibrational mode internal to the acceptor chromophore can be preferentially driven by electronically nonresonant impulsive stimulated Raman (or resonant infrared) excitation with a short polarized control pulse. A subsequent electronically resonant polarized pump then preferentially e…

Environment-assisted quantum transport and trapping in dimers

We study the dynamics and trapping of excitations for a dimer with an energy off-set $Δ$ coupled to an external environment. Using a Lindblad quantum master equation approach, we calculate the survival probability $Π(t)$ of the excitation and define different lifetimes $τ_s$ of the excitation, corresponding to the duration of the decay of $Π(t)$ in between two predefined values. We show that it is not possible to always enhance the overall decay to the trap. However, it is possible, even for not too small environmental couplings and for values of $Δ$ of the order ${\cal O}(1)$, to decrease cer…

Dimerization-assisted energy transport in light-harvesting complexes

We study the role of the dimer structure of light-harvesting complex II (LH2) in excitation transfer from the LH2 (without a reaction center (RC)) to the LH1 (surrounding the RC), or from the LH2 to another LH2. The excited and un-excited states of a bacteriochlorophyll (BChl) are modeled by a quasi-spin. In the framework of quantum open system theory, we represent the excitation transfer as the total leakage of the LH2 system and then calculate the transfer efficiency and average transfer time. For different initial states with various quantum superposition properties, we study how the dimeri…

Engineering coherent interactions in molecular nanomagnet dimers

Proposals for systems embodying condensed matter spin qubits cover a very wide range of length scales, from atomic defects in semiconductors all the way to micron-sized lithographically-defined structures. Intermediate scale molecular components exhibit advantages of both limits: like atomic defects, large numbers of identical components can be fabricated; as for lithographically defined structures, each component can be tailored to optimize properties such as quantum coherence. Here, we demonstrate what is perhaps the most potent advantage of molecular spin qubits, the scalability of quantum …

莫特区域费米子异核二聚体的杰恩斯-卡明斯动力学

Jaynes--Cummings dynamics of fermionic heteronuclear dimers in the Mott regime

该研究构建并精确求解深晶格莫特区域费米子异核二聚体的相干转换模型，将其映射为杰恩斯-卡明斯哈密顿量，推导了相关动力学的精确解析表达式，为对应物理提供了物质波实现与可解框架。

Optical Excitations of Chlorophyll $a$ and $b$ Monomers and Dimers

A necessary first step in the development of technologies such as artificial photosynthesis is understanding the photoexcitation process within the basic building blocks of naturally-occurring light harvesting complexes (LHCs). The most important of these building blocks in biological LHCs such as LHC II from green plants are the chlorophyll $a$ (Chl $a$) and chlorophyll $b$ (Chl $b$) chromophores dispersed throughout the protein matrix. However, efforts to describe such systems are still hampered by the lack of computationally efficient and accurate methods that are able to describe optical a…