CCPQ: Quantum Dynamics in Atomic, Molecular and Optical Physics

量子粒子的动力学是描述物质世界的基础。原子核之间的碰撞提供了基本的化学反应，而电子在原子核周围的运动提供了精细的机械细节。为了理解这些运动，我们需要求解与时间相关的薛定谔方程--对于超过3个粒子来说，这不是一个微不足道的问题，需要巨大的计算工作量。最先进的实验使用阿秒或飞秒的辐射脉冲使我们能够跟踪这些粒子的运动，但如果没有计算机模拟，结果很难理解。由于提供了新的光源，如自由电子激光(FEL)，这一研究领域目前正在经历巨大的扩展，需要开发软件来跟上新的能力。CCPQ有两个社区代码(R-矩阵套件、MCTDH波包动力学)来处理这些过程。这些结果深入到了分子的基本反应性，其中必须考虑量子力学行为。反物质粒子的相互作用也是一个非常感兴趣的话题，主要是因为正电子在医学成像中的使用，但也作为基础科学领域的实验，如阿尔法计划。在这里，反物质粒子与正常物质碰撞，并研究不同的衰变通道。CCPQ正在与实验者合作开发一种代码，以帮助理解这些听起来奇怪但有用的粒子的行为。从几个物体到多个物体介绍了物理学中一些最令人着迷的现象，如超流、超导和铁电。然而，直接模拟它们也会带来随系统大小呈指数级增长的计算开销。虽然通常是像强关联物理学这样的凝聚态系统的保留地，但现在可以通过受控的方式访问粒子的集体行为，冷原子被困在光学晶格中。这打开了以前无法在多体系统中获得的相干动力学的实验审视，比如研究如果粒子的相互作用和动能在量子相变中熄灭会发生什么。这一独特视角的进展现在又回到了凝聚态问题上，其中太赫兹辐射在飞秒时间尺度上的相互作用也揭示了固态系统中关联的相干电子运动。这个强关联多体动力学的主题是CCPQ开发的最后一串--体现在TNT项目中，该项目引入了压缩多体状态以克服指数障碍的新方法。它不仅将支持冷原子量子模拟的新兴量子技术，而且最终还可能有助于设计和控制具有巨大技术潜力的光脉冲可以切换超导或铁电等性质的真实材料。CCPQ通过提供一个交流思想的论坛，通过为研究人员提供帮助传播代码的网络机会，并通过支持代码用户的培训研讨会，支持这些世界领先的社区代码的开发。它还以达累斯伯里实验室的计算机专家的形式提供直接支持，他们帮助优化代码，以便在大型高性能计算机(HPC)上使用。

The dynamics of quantum particles is the basis to describing the material world. Collisions between nuclei provides basic chemical reactivity, while the movements of electrons around nuclei provides the fine mechanistic details. To understand these motions we need to solve the time-dependent Schroedinger equation - a non-trivial problem for more than 3 particles that requires a huge computational effort.State-of-the art experiments using attosecond or femtosecond pulses of radiation allow us to follow the motion of these particles, but without computer simulations the results are difficult to understand. This field of research is presently undergoing a huge expansion, due to the provision of new light sources such as free electron lasers (FELs), and software needs to be developed to keep up to the new capabilities. CCPQ has two community codes (R-matrix suite, MCTDH wavepacket dynamics) to treat these processes. The results give a deep inside into the fundamental reactivity of molecules, where quantum mechanical behaviour must be considered.The interactions of anti-matter particles are also a topic of much interest, primarily due to the use of positrons in medical imaging, but also as a field of fundamental science in experiments such as the ALPHA project. Here, anti-matter particles are collided with normal matter and the different decay channels investigated. CCPQ is developing a code in collaboration with experimentalists to help understand the behaviour of these exotic sounding, but useful, particles. Going from few bodies to many-bodies introduces some of the most fascinating phenomena in physics, such as superfluidity, superconductivity and ferroelectricity. However, to directly simulate them also introduces an exponentially scaling overhead in computation effort with the system size. While usually the preserve of condensed matter systems such strongly-correlated physics, where particles behaviour collectively, are now accessible in controlled ways with cold-atoms trapped in optical lattices. This has opened up previously inaccessible coherent dynamics in many-body systems to experimental scrutiny, such as examining what happens if the interaction and kinetic energies of particles are quenched across a quantum phase transition. The advances of this unique perspective are now reciprocating back to condensed matter problems where interaction of THz radiation on femtosecond timescales is also revealing correlated coherent electrons motion in solid-state systems. This topic of strongly-correlated many-body dynamics is the final strand of CCPQ development - embodied by the TNT project which introduces new ways of compressing many-body states to overcome the exponential barrier. It will support not only the emerging quantum technology of cold-atom quantum simulation, but also may eventually aid in designing and controlling real materials where optical pulses can switch properties such as superconductivity or ferroelectricity with great technological potential.CCPQ supports the development of these world leading community codes by providing a forum for the exchange of ideas, by providing networking opportunities for researchers to help disseminate the codes, and by supporting training workshops for users of the codes. It also provides direct support in the form of computer experts at the Daresbury laboratory who help optimise the codes for use on large high performance computers (HPC).