Quantum/Classical Boundaries in Matter-Wave Solitons

摘要：物理学家发现，量子力学可以完美地描述由单个或少量电子、质子或原子组成的微观世界。这些小系统中的量子相关性，被称为“量子纠缠”，是推动实现量子计算的主要属性。然而，要使量子计算机表现出优于普通经典计算机的优势，纠缠粒子的数量必须很大，从而给它们的实现带来技术和基础上的障碍。美国国家科学基金会资助的研究生研究人员将在迄今为止最大的系统中使用自稳定的原子波包（称为孤子）进行实验，探索量子纠缠的极限。尽管对于包含多达10,000个原子的量子系统来说，孤子很大，但被限制在一维线上的孤子具有特殊的鲁棒性，这使它们成为探索量子物理在宏观世界中扩展到什么程度的理想选择。这些实验将帮助我们理解量子/经典边界，以及如何将其扩展到更大的系统。通过进行这些实验，研究生，其中一些来自代表性不足的群体，在最先进的实验室学习实验原子物理学的方法，获得专业知识，这些专业知识将在学术界，政府或工业中追随他们的职业生涯。摘要：孤子是出现在非线性系统中的无色散激励。它们存在于经典和量子波现象中，例如在水中、等离子体、光纤和物质波中传播的波，仅举几个例子。孤子是为数不多的由精确可积模型描述的非平凡系统之一。研究人员将继续对具有吸引力相互作用的玻色-爱因斯坦凝聚产生的明亮物质波孤子进行实验研究，具体来说，他们将探索可积性在确定量子/经典边界中的作用。最近的理论预测，可积性将保护宏观/介观物体免受退相干的影响，并可能导致观察到明显的量子效应，这些效应预计将最好地由平均场理论描述。通过利用可积性，量子涨落和量子纠缠的影响可以扩展到具有大量自由度的系统，并且这些系统在物理尺寸上很大。研究小组有两个具体目标：1)观察量子涨落对高阶孤子呼吸器结合的可积性破坏效应；2)研究基本孤子与由光片构成的排斥势垒相互作用的快慢碰撞机制，并利用这种几何结构实现物质波孤子干涉仪。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

General audience abstract: Physicists have found that quantum mechanics works perfectly to describe the micro-world of single or small numbers of electrons, protons, or atoms. Quantum correlations in these small systems, known as “quantum entanglement,” are the primary attribute driving the quest to realize quantum computation. For a quantum computer to exhibit an advantage over an ordinary classical computer, however, the number of entangled particles must be large, thus presenting obstacles, both technical and fundamental, to their implementation. NSF-funded graduate student researchers will perform experiments that explore the limits of quantum entanglement in the largest systems to date using self-stabilizing wavepackets of atoms, known as solitons. Although large for a quantum system, containing as many as 10,000 atoms, solitons confined to a one-dimensional line are bestowed with a special robustness that makes them ideal for exploring how far quantum physics may be extended into the macro-world. These experiments will help us understand the quantum/classical boundary, and how it may be extended to even larger systems. By performing these experiments, graduate students, several from underrepresented groups, learn the methods of experimental atomic physics in a state-of-the-art laboratory, gaining expertise that will follow them in their careers in academia, government, or industry. Technical audience abstract:Solitons are dispersion-less excitations that arise in nonlinear systems. They are found both in classical and quantum wave phenomena, such as waves propagating in water, plasmas, optical fibers, and in matter waves to name just a few examples. Solitons are one of the few non-trivial systems that are described by an exactly integrable model. The researchers will continue their experimental investigation of bright matter-wave solitons produced from Bose-Einstein condensates with attractive interactions, and specifically, they will explore the role of integrability in determining the quantum/classical boundary. Recent theory predicts that integrability will protect a macro/mesoscopic object from decoherence, and can lead to the observation of effects that are manifestly quantum in objects expected to be best described by mean-field theories. By harnessing integrability, the effects of quantum fluctuations and quantum entanglement may be extended to systems with a large number of degrees of freedom, and which are large in physical size. The research team has two specific goals: 1) to observe the integrability-breaking effect of quantum fluctuations on the binding of a higher-order soliton breather and 2) to study the fast and slow collision regimes of a fundamental soliton interacting with a repulsive barrier made from a light sheet, and to exploit this geometry to realize a matter-wave soliton interferometer.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.