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性，而原子核周围电子的运动提供了精细的机械细节。为了理解这些运动，我们需要解决与时间相关的薛定谔方程——一个超过3个粒子的非平凡问题，需要大量的计算工作。使用阿秒或飞秒辐射脉冲的最先进的实验使我们能够跟踪这些粒子的运动，但没有计算机模拟的结果很难理解。由于提供了新的光源，如自由电子激光器（FELs），这一研究领域目前正在经历一个巨大的扩展，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。这些结果让我们深入了解了分子的基本反应性，这是必须考虑量子力学行为的地方。反物质粒子的相互作用也是一个非常有趣的话题，主要是由于正电子在医学成像中的使用，但也作为基础科学实验领域，如ALPHA项目。在这里，反物质粒子与正常物质碰撞，并研究了不同的衰变通道。CCPQ正在与实验学家合作开发一种代码，以帮助理解这些听起来很奇怪但很有用的粒子的行为。从少体到多体引入了一些最迷人的物理现象，如超流体、超导性和铁电性。然而，直接模拟它们也会导致系统大小的计算开销呈指数级增长。虽然通常是凝聚态系统的专利，但这种强相关物理，即粒子的集体行为，现在可以用被困在光学晶格中的冷原子来控制。这打开了先前无法进入的多体系统相干动力学的实验研究，例如检查如果粒子的相互作用和动能在量子相变中被淬灭会发生什么。这一独特视角的进步现在又回到了凝聚态问题，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相关的相干电子运动。强相关多体动力学是CCPQ发展的最后一环，TNT项目介绍了压缩多体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性或铁电性等特性的真实材料。CCPQ通过提供交流思想的论坛、为研究人员提供帮助传播代码的网络机会以及支持为代码用户举办培训讲习班，支持这些世界领先的社区代码的开发。它还以达斯伯里实验室计算机专家的形式提供直接支持，帮助优化用于大型高性能计算机（HPC）的代码。

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).