Quantum dynamics in closed and open many-particle systems

封闭和开放多粒子系统中的量子动力学

• 批准号: 2397290
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2397290
• 关键词: Quantum; dynamics; closed; open; many

This project falls within the Physical Sciences Theme and the Physics grand challenge area "Emergence and Physics Far From Equilibrium". The first line of work is concerned with analysing novel non-equilibrium steady states that are realizable in cold atom experiments. It is well known that the attractive Lieb-Liniger model (bosons with attractive delta-function interaction) is thermodynamically unstable in equilibrium, but due to the existence of conservation laws can support stable non-equilibrium steady states after quantum quenches. In cold atom systems that are approximately described by the Lieb-Liniger model these correspond to metastable states. In particular, quenching the interaction strength from very strong repulsion to very strong attraction realizes the so-called super-Tonks-Girardeau gas [E. Haller et al, Science 325, 1224 (2009)]. Quenching to less strongly attractive interactions is expected to generate more exotic highly correlated steady states with an intricate hierarchical structure of many-boson bound states [L. Piroli et al, Phys. Rev. Lett. 116 (7), 070408 (2016)]. The aim of this part of the project is to characterize the physical properties of this class of states by using the recently developed framework of Generalized Hydrodynamics to determine linear response functions and by considering the dynamics under expansion. The next step will be to develop a full theory for an interaction quench from the ground state of the infinitely repulsive to the attractive Lieb-Linger model by means of the quench action approach. The second line of work is concerned with the description of open quantum systems by Lindblad equations. The aim is to describe the short-time dynamics of Lindblad equations for many-particle systems using bosonization methods. In the first instance the bath coupling will be taken to be dephasing noise, while the Hamiltonian part allows a description in terms of a free boson (plus perturbations). The first goal is to establish the time window over which linear Luttinger liquid theory provides a good description of the Hamiltonian part. This will be done by considering exactly solvable models and by comparing to numerical matrix product state computations. The second goal is to go beyond the linear Luttinger liquid description and consider the role played by different kinds of perturbations by using equation of motion techniques. The ultimate goal is to develop a readily useable extension of Luttinger liquid theory to open quantum systems.

该项目属于物理科学主题和物理大挑战领域“出现和物理远非平衡”。第一线工作与分析在冷原子实验中可实现的新型非平衡稳态有关。众所周知，有吸引力的Lieb-Liniger模型（具有吸引人的Delta功能相互作用的玻色子）在平衡方面在热力学上是不稳定的，但是由于存在保护法可以在量子淬火后支持稳定的非平衡稳态。在lieb-Liniger模型近似描述的冷原子系统中，这些系统对应于亚稳态。特别是，从非常强烈的排斥力到非常强烈的吸引力淬灭相互作用的强度实现了所谓的超级吨位 - 吉拉多气[E. E. Haller等人，Science 325，1224（2009）]。预计将淬灭到较不吸引人的相互作用将产生更外来的高度相关稳态，并具有多个玻色子结合状态的复杂分层结构[L. Piroli等人，物理。莱特牧师。 116（7），070408（2016）]。该项目的这一部分的目的是通过使用最近开发的广义流体动力学框架来确定线性响应函数并考虑扩展下的动力学来表征这类状态的物理性质。下一步将是通过淬灭行动方法从无限排斥的基础状态开发出一种完整的理论，以从无限排斥的基础状态到有吸引力的Lieb-Linger模型。第二行的工作与Lindblad方程式对开放量子系统的描述有关。目的是用持续化方法描述许多粒子系统的Lindblad方程的短时动力学。首先，浴联耦合将被视为发出噪音，而哈密顿部分则允许用自由玻色子（加上扰动）进行描述。第一个目标是确定线性Luttinger液体理论对哈密顿部分的良好描述的时间窗口。这将通过考虑准确的可解决模型并与数值矩阵乘积状态计算进行比较来完成。第二个目标是超越线性Luttinger液体描述，并通过使用运动技术方程来考虑各种扰动所起的作用。最终目标是将Luttinger液体理论的易于使用的扩展开发到打开量子系统。