HOBr/DOBr态到态光解动力学的量子波包研究

本文基于高水平的多参考组态相互作用计算,报导了HOBr的最低三个单重态的三维势能面. 并且对该分子的光解离过程用实波包传播的方法进行了量子动力学研究,不仅计算结果得到了吸收光谱,而且还产生了光解产物的内态和角度分布. 结果与在紫外区域测得的HOBr的总吸收截面定量吻合,并很好的重现了实验上在266 nm处观察到的振动冷和转动热的光解OH/OD产物. 此外,预测了OH/OD的反冲各向异性参数接近平行跃迁的极限值,表明在266 nm处从基态(1¹A'')到2¹A''态的面内跃迁是一个快速的解离过程. 这与实验上从测量转动取向得出的结论一致. 然而,想要实现与实验上的定量一致,还需要考虑自旋和电子角动量的影响.     

乙醛光解动力学的离子速度成像

利用时间切片离子速度成像技术在275～321 nm能量范围内重新研究了乙醛自由基通道CH₃+HCO的光解动力学. 通过共振增强多光子电离的方法探测甲基碎片. 对甲基的伞形振动基态和激发态(v₂=0和1)进行了影像探测. 乙醛通过T₁电子态系间窜越到S₁电子态的解离产物具有很高的动能释放和很低的内能激发,碎片的振动能和转动能随激发能量的增加而增加. 乙醛T₁电子态的势垒高度经测量高于基电子态3.881±0.006 eV.     

不同初始振动态下D2O在B带的态-态光解动力学

利用高精度的非绝热从头算势能面,采用量子实波包方法研究了D₂O在3个不同初始振动态(0,1,0)、(1,0,0)和(0,0,1)下光激发到~B态解离过程的态-态量子动力学．结果表明,由于初始振动波函数的形状不同,从不同振动态产生的吸收光谱、产物分布和产物分支比具有不同的动力学特性．弯曲振动态(010)的吸收谱呈现出两波瓣的形状且中间具有较浅的极小值,其基态产物OD( ~X)在高能量区域会出现轻微的振动态反转现象．所有初始振动态得到的激发态产物OD(_?)的振-转态分布都随能量的变化出现强烈的震荡,这是由于受到了激发态势能面上长寿命共振态的影响．反对称伸缩振动态(0,0,1)在高能量区域具有较大的产物分支比OD(_?)/OD( ~X),表明绝热通道在某些情形下是主要的解离通道．     

利用离子-中性光解碎片符合成像研究离子光解动力学

本文对最近研制的低温离子阱-离子速度成像谱仪进行升级,实现了探测离子光解反应的离子产物和中性产物速度影像的符合探测. 实验上利用自制的低温圆柱形离子阱对制备的离子样品进行富集和冷却. 从离子阱中引出的离子束准直后进入一组电势切换电极和离子速度聚焦成像系统开展激光光解实验. 利用一组新设计的离子引出、加速和聚焦电场,离子束可以被加速至4500 eV以上,使中性解离产物获得足够的平动能而被位置灵敏的影像探测器直接探测. 本文利用Ar₂⁺离子的355 nm光解反应对升级后的装置进行测试. 结果表明,光解产生的中性Ar原子和Ar⁺离子产物的速度影像分辨率分别为Δv/v≈4.6%和1.5%.     

两个二能级原子与辐射场的量子动力学性质

用完全量子化方法研究两个二能级原子与腔场相互作用过程中，原子能级占居几率与辐射场的量子动力学性质，讨论了原子间耦合及激光发场对上述性质的影响，揭示了原子耦合与原子－场相互作用之间的联系。     

阴离子表面活性剂存在下氯化血红素光解动力学研究

利用罗丹明B(RhB)-H₂O₂化学发光体系及流动注射技术,研究了十二烷基磺酸钠(SDS)存在下,氯化血红素在紫外光下的光解反应动力学规律,并与不加入SDS时氯化血红素光解行为进行了对比。 结果表明：SDS存在与否,氯化血红素的光解行为均符合一级动力学反应方程。 但是加入SDS后所形成的胶束相,减缓了氯化血红素的光解速度,提高了其光稳定性。     

量子系统的动力学对称性研究与代数动力学

文章介绍了量子系统的动力学对称性理论和代数动力学在人造了系统和量子光学系统中的应用。     

基于原子系综集体激发的量子存贮

近几年来,人们从理论和实验两个方面探讨了利用自由原子系综作为量子记忆体的可能性. 基于固定于格点上Λ型“原子”系综的准自旋波激发的研究, 提出了实现光子信息量子存贮的新方案. 这个方案的目标是为了克服自由原子系综量子存贮方案中存在的量子态漏损诱导退相干的致命问题. 研究过程中发现了系综型量子记忆体中隐藏动力学的对称性和其绝热暗态演化的选择定则. 为了确切地表述这个工作的意义,还扼要地介绍这个方案建立的前期关于原子系综对称集体激发的系列工作. In this article we reviews a new protocol of quantum memory based on the quasi pin wave excitation of the Λ systems fixed the sites of lattice. This protocol tries to avoid the disadvantage of the quantum memory scheme based on free atom ensemble, the quantum decoherence induced by the quantum leakage of collective state. Especially,we discover a universal dynamic symmetry hidden in various ensemble based quantum storage scheme. To understand the significance of this work exactly, we also give a brief introduction to our systematical studies on collective symmetric excitons in quantum ensemble,which is the necessary to propose the present scheme for quantum memory.     

水相中金纳米颗粒催化的醛基选择性氧化

本文开发了一种新型的用生物质淀粉保护的金纳米颗粒作为催化剂,选择性氧化醛基得到羧酸的方法. 在4-羟甲基苯甲醛的催化氧化中,金纳米颗粒对醛基表现出了压倒性的选择性,而醇羟基则保持不变. 该非均相催化体系由可溶解的催化剂和不溶解的底物构成. 金催化剂的制备、储存、和使用都在水相中. 反应条件优化之后,双氧水被证明是最佳的氧化剂,可以得到100%转化率. 此外,在不同官能团取代的醛衍生物中,金纳米颗粒也表现出了很好的普适性. 反应结束之后,有机组分被有机溶剂萃取,而金颗粒被保留在水中通过分液分离以回收使用.     

Dynamical learning of non-Markovian quantum dynamics

We study the non-Markovian dynamics of an open quantum system with machine learning.The observable physical quantities and their evolutions are generated by using the neural network.After the pre-training is completed,we fix the weights in the subsequent processes thus do not need the further gradient feedback.We find that the dynamical properties of physical quantities obtained by the dynamical learning are better than those obtained by the learning of Hamiltonian and time evolution operator.The dynamical learning can be applied to other quantum many-body systems,non-equilibrium statistics and random processes.     

Recurrent versus diffusive dynamics for a kicked quantum system

We study the dynamics of a two-level quantum system subject to a time-dependent kicking perturbation modulated along the Thue-Morse sequence. For a nontrivial set of the parameters, the quantum autocorrelation function is explicitly calculated, and splits into a purely recurrent and a purely diffusive part. Furthermore, the diffusive part is directly related to the (singular continuous) correlation measure of the Thue-Morse sequence.     

Entanglement dynamics of two-qubit systems in different quantum noises

The entanglement dynamics of two-qubit systems in different quantum noises are investigated by means of the operator-sum representation method.We find that,except for the amplitude damping and phase damping quantum noise,the sudden death of entanglement is always observed in different two-qubit systems with generalized amplitude damping and depolarizing quantum noise.     

Thermal quantum time-correlation functions from classical-like dynamics

Thermal quantum time-correlation functions are of fundamental importance in quantum dynamics, allowing experimentally measurable properties such as reaction rates, diffusion constants and vibrational spectra to be computed from first principles. Since the exact quantum solution scales exponentially with system size, there has been considerable effort in formulating reliable linear-scaling methods involving exact quantum statistics and approximate quantum dynamics modelled with classical-like trajectories. Here, we review recent progress in the field with the development of methods including centroid molecular dynamics , ring polymer molecular dynamics (RPMD) and thermostatted RPMD (TRPMD). We show how these methods have recently been obtained from ‘Matsubara dynamics’, a form of semiclassical dynamics which conserves the quantum Boltzmann distribution. We also apply the Matsubara formalism to reaction rate theory, rederiving t → 0₊ quantum transition-state theory (QTST) and showing that Matsubara-TST, like RPMD-TST, is equivalent to QTST. We end by surveying areas for future progress.     

量子计算与量子模拟

量子计算和量子模拟在过去的几年里发展迅速,今后涉及多量子比特的量子计算和量子模拟将是一个发展的重点.本文回顾了该领域的主要进展,包括量子多体模拟、量子计算、量子计算模拟器、量子计算云平台、量子软件等内容,其中量子多体模拟又涵盖量子多体动力学、时间晶体及多体局域化、量子统计和量子化学等的模拟.这些研究方向的回顾是基于对现阶段量子计算和量子模拟研究特点的考虑,即量子比特数处于中等规模而量子操控精度还不具有大规模逻辑门实现的能力,研究处于基础科研和实用化的过渡阶段,因此综述的内容主要还是希望管窥今后的发展.     

Full counting statistics of renormalized dynamics in open quantum transport system

The internal dynamics of a double quantum dot system is renormalized due to coupling respectively with transport electrodes and a dissipative heat bath. Their essential differences are identified unambiguously in the context of full counting statistics. The electrode coupling caused level detuning renormalization gives rise to a fast-to-slow transport mechanism, which is not resolved at all in the average current, but revealed uniquely by pronounced super-Poissonian shot noise and skewness. The heat bath coupling introduces an interdot coupling renormalization, which results in asymmetric Fano factor and an intriguing change of line shape in the skewness.     

Interaction between classical and quantum systems and the measurement of quantum observables

Quantum mechanics presumes classical measuring instruments with which they interact. The problem of measurement interaction between classical and quantum systems is posed and solved. The restriction to compatible measurements comes about naturally as the condition for the integrity of the classical system. A technical device is the perspective on classical mechanics as quantum mechanics with essentially hidden dynamical variables. Work supported in part by U.S. Atomic Energy Commission, ERDA.     

Causality, symmetries and quantum mechanics

It is argued that there is no evidence for causality as a metaphysical relation in quantum phenomena. The assumptions that there are no causal laws, but only probabilities for physical processes constrained by symmetries, leads naturally to quantum mechanics. In particular, an argument is made for why there are probability amplitudes that are complex numbers. This argument generalizes the Feynman path integral formulation of quantum mechanics to include all possible terms in the action that are allowed by the symmetries, but only the lowest order terms are observable at the presently accessible energy scales, which is consistent with observation. The notion of relational reality is introduced in order to give physical meaning to probabilities. This appears to give rise to a new interpretation of quantum mechanics.     

CdTe/CdS核壳结构量子点超快载流子动力学

在水相合成CdTe以及CdTe/CdS核壳结构量子点基础上, 利用基于抽运-探测技术的瞬态差分透射技术研究了CdTe量子点以及不同CdS壳层厚度的CdTe/CdS量子点的最低激子能态的超快激发与弛豫动力学. 研究表明:相比于CdTe,CdTe/CdS量子点的电子空穴由于空间分离,其所需的激发时间要长于电子空穴空间重叠态所需要的激发时间.随着壳层厚度的增加, 量子点表面的钝化有效地减少了表面态相关弛豫机理,并延长相对应的弛豫时间.