Strong correlation physics in ultra cold atomic gases

超冷原子气体中的强相关物理

• 批准号: EP/D070082/1
• 负责人: Andrew Ho
• 金额: $ 57.39万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD070082%2F1
• 关键词: Strong; correlation; physics; ultra; cold

I plan to study theoretically some fundamental questions in physics, which involves new forms of matter. Very recent experiments have created a new material at record low temperatures, never seen before in the Universe. Unlike materials made by labs all over the world, most aspects of this material is under the direct control of the experimentalists, and can even be changed into something completely different after the material was created. In everyday materials and materials created in labs, the atoms, electrons and ions interact amongst themselves: this leads to the atoms having a preferred distance between each other, and this dictates what the structure and properties the material has. In this new material however, the atoms are trapped at extremely low temperatures into a regular pattern: this pattern is created by a set of lasers that experimentalists can control. For example, it is easy to make the atom stay at rest, rather than hop around on this regular pattern, just by changing the intensity of the laser. Or we can change the types and number of atoms trapped in this pattern; even the interactions between the atoms can be changed. Furthermore, there are no dirt nor defects in this artificial material, unlike in real solids. All this has to happen at extremely low temperatures, so that the atoms cannot move around too much. Then, atoms obey the laws of quantum mechanics: the basic laws of physics at small distances and low temperatures, which say that particles like atoms also behave like waves (as in light waves). Thus, much richer and stranger phenomena can occur in this new artificial material.With this ease and level of control, it becomes possible to study a whole range of fundamental quantum phenomena that are difficult--or impossible--to study in normal materials. Working in parallel with experimentalists, I plan to study what happens to the trapped cold atoms, when there are strong interactions between the atoms. For example, when atoms are forced to stay in a line, they cannot avoid each other (just as in a traffic jam!). When one atom moves a bit, this affects its neighbours, which in turn affects their neighbours, and so on. The end result is that all of the atoms participate together to form a global pattern of motion: the individuality of the atoms are lost altogether. Physicists have developed sophisticated mathematical methods to treat such behaviour in real solids. I plan to use such techniques (and perhaps invent some new ones) to see how new exotic forms of matter can develop, when we change various aspects of this new material . For example, if we put in more than one type of atoms, and there is attraction between the different types, but repulsion between the same type, then one atom of each type may clump together to form a new particle, and these new particles may in turn form a new global pattern. Furthermore, experimentalists can follow in time how changes occur, which is rather hard to do in normal materials. Thus, I plan to study how the new forms of matter may change from one form to another, when we slowly or suddenly change some aspects of the material . In my proposed work, I will calculate properties of these new forms of matter, to compare with experiments. This in turn may suggest new experiments to help us understand the basic principles underlying these new forms of matter. Furthermore, these new principles may benefit the study of strong interactions in more normal materials. Finally, it has been proposed that this sort of artificial material can be used for quantum computing. This takes advantage of the quantum wave-like nature of atoms to process information in parallel, to hugely increase computing power. My work will provide the basic understanding needed for this potentially revolutionary application.

我计划从理论上研究物理学中的一些基本问题，其中涉及新的物质形式。最近的实验在创纪录的低温下创造了一种新材料，这是宇宙中从未见过的。与世界各地实验室制造的材料不同，这种材料的大部分方面都在实验人员的直接控制之下，甚至可以在材料被创造出来后变成完全不同的东西。在日常材料和实验室创建的材料中，原子、电子和离子之间相互作用：这导致原子之间具有优选的距离，这决定了材料具有的结构和特性。然而，在这种新材料中，原子在极低的温度下被捕获成规则的图案：这种图案是由实验人员可以控制的一组激光产生的。例如，只需改变激光的强度，很容易使原子保持静止状态，而不是在这种规则的模式上跳跃。或者我们可以改变陷入这种模式的原子的类型和数量；甚至原子之间的相互作用也可以改变。此外，与真正的固体不同，这种人造材料没有污垢或缺陷。所有这一切都必须在极低的温度下发生，以便原子不能移动太多。然后，原子遵循量子力学定律：短距离和低温下的基本物理定律，它表明像原子这样的粒子也表现得像波（如光波）。因此，在这种新的人造材料中可以发生更丰富和更奇怪的现象。有了这种易于控制的控制水平，就有可能研究在普通材料中难以或不可能研究的一系列基本量子现象。我计划与实验学家同时工作，研究当原子之间存在强相互作用时，被捕获的冷原子会发生什么。例如，当原子被迫排成一行时，它们无法相互避开（就像交通堵塞一样！）。当一个原子移动一点时，就会影响其邻居，进而影响其邻居，依此类推。最终结果是所有原子一起参与形成整体运动模式：原子的个体性完全消失。物理学家已经开发出复杂的数学方法来处理真实固体中的这种行为。我计划使用这样的技术（也许还发明一些新的技术）来看看当我们改变这种新材料的各个方面时，新的奇异物质形式如何发展。例如，如果我们放入不止一种类型的原子，并且不同类型之间存在吸引力，而同一类型之间存在排斥力，那么每种类型的一个原子可能会聚集在一起形成一个新的粒子，而这些新粒子又可能会形成一个新的全局模式。此外，实验人员可以及时跟踪变化是如何发生的，这在普通材料中很难做到。因此，我计划研究当我们缓慢或突然改变材料的某些方面时，物质的新形式如何从一种形式转变为另一种形式。在我提出的工作中，我将计算这些新形式物质的属性，以与实验进行比较。这反过来可能会提出新的实验来帮助我们理解这些新物质形式背后的基本原理。此外，这些新原理可能有利于研究更普通材料中的强相互作用。最后，有人提出这种人造材料可以用于量子计算。这利用了原子类似量子波的性质来并行处理信息，从而极大地提高了计算能力。我的工作将为这个潜在的革命性应用程序提供所需的基本理解。

项目成果

Feshbach resonant scattering of three fermions in one-dimensional wells

一维井中三个费米子的 Feshbach 共振散射

• DOI: 10.1103/physreva.80.033611
• 发表时间: 2009
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Ðuric T

Effect of disorder on a Pomeranchuk instability

无序对 Pomeranchuk 不稳定性的影响

• DOI: 10.1209/0295-5075/84/27007
• 发表时间: 2008
• 期刊: EPL (Europhysics Letters)
• 作者: Ho A

Quantum Simulation of the Hubbard Model: The Attractive Route

哈伯德模型的量子模拟：有吸引力的路线

• DOI: 10.48550/arxiv.0812.4422
• 发表时间: 2008
• 作者: Ho A