Asymmetric Fermi Superfluids and Engineered Quantum Systems

不对称费米超流体：电子有两种类型--自旋上升和自旋下降。在超导体中，每个自旋向上的电子加入一个自旋向下的电子，形成所谓的库珀对。它们负责无耗散地传导电流。问题出现了--当自旋向上的电子多于自旋向下的电子时，会发生什么？什么是最好的方法来容纳额外的旋转？事实证明，这是一个极其困难的问题，而且在40多年后仍然是一个悬而未决的问题。最近，我们有了一个新的实验系统--冷原子气体(而不是电子)，它表现出与超导体相同的物理性质，而且实验比电子更容易执行和解释，所以我们有真正的机会来解决这个难题。我们还可以问，如果我们把不同质量的原子配对，而不是玩不同的自旋，会发生什么--这个问题很难用电子来问。我的研究将有助于解释在寻找预计将出现在这些系统中的新物质相的实验。此外，我希望在问题解决的最后能够提供一个统一的理论框架。工程量子系统：1)非平衡物理-冷原子非常慢，我们可以比它们反应所需的时间更快地改变它们在实验室中经历的条件！我们也可以在行动中拍摄它们。这让我们能够研究它们在对我们所做的事情(比如压缩它们，突然给它们更多能量等等)做出反应时进行自我调整时所经历的复杂运动。这是一个新的领域，因为其他系统(如金属中的电子)通常移动得太快，我们看不到它们在做什么。这也是探索所谓的多体量子力学的一种新方法--当有许多原子处于与时间相关的情况下时会发生什么。2)量子信息接口--量子计算的最新进展提出了混合量子计算的概念。有些系统(比如俘获离子)对量子比特来说是非常好的记忆。其他的(比如坚固的状态节点结构)作为CPU工作得很好。我们如何在它们之间传输量子比特，以及哪些系统耦合得最好？我建议研究各种原子-固态系统，以寻找最好的接口技术，这有望在不久的将来成为一个重要的研究领域。

Asymmetric Fermi Superfluids: electrons come in two types - called spinup and spin down . In superconductors each spin up electron joins a spindown electron to form what is called a Cooper pair. These are responsiblefor conducting electric current without dissipation. The question arises -what happens when there are more spin up than spin down electrons? What isthe best way to accomodate the extra spin up ones? It turns out that thisis an extremely difficult and still open problem after more than fortyyears. Recently we have a new experimental system - cold gases of atoms (instead ofelectrons) which exhibit the same physics as superconductors and theexperiments are much easier to perform and interpret than with electronsso we have a real opportunity to solve this puzzle. We can also ask whatwould happen if instead of playing with different spins we paired atomswith different masses - a question which cannot be easily asked withelectrons. My research will help to interpret experiments in the search for new phases of matter which are expected to appear in these systems. Further, I hope to be able to provide a unified theoretical framework at the end when the problem is solved.Engineered Quantum Systems: 1) nonequilibrium physics - cold atoms arevery slow and we can change the conditions they experience in the labfaster than the time it takes them to react! We can also photograph themin action. This allows us to study the complicated motions that theyundergo as they rearrange themselves in response tosomething that we did (like compressing them, suddenly giving them moreenergy, etc). This is a new field since other systems (such as electronsin metals) usually move too fast for us to see what they are doing. It is also a new way of exploring so-called many-body quantum mechanics - what happens when there are many atoms in a time-dependent situation. 2) interfaces for quantum information - recent progress in quantum computing has proposed the idea of hybrid quantum computing. Some systems (liketrapped ions) are very good memories for qubits. Others (like solid statenanostructures) work very well as CPUs. How do we transfer qubits betweenthem and which systems couple best? I propose to study a variety ofatom-solid state systems in search of the best interface technology inwhat promises to become a vital area of research in the near future.