RUI - The Physics of Coupled Atomic-Molecular Condensate Systems

RUI - 耦合原子分子凝聚系统的物理

• 批准号: 0555646
• 负责人: Hong Ling
• 金额: $ 7.5万
• 依托单位: Rowan University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-15 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0555646&HistoricalAwards=false
• 关键词: RUI; Physics; Coupled; Atomic; Molecular

The primary objective of this proposal is to explore the physics of multi-component condensatescontaining both atomic and molecular species, one of the most rapidly evolving areas of physics research. Of particular interest is the two-color Raman photo-association model (or its Feshbach equivalence), also known as the nonlinear system, where a pair of stable atoms is either photo-associated (or magnetoassociated) into an unstable excited molecule, which is subsequently driven into a stable (ground) molecular state by a laser field. The nonlinear system supports a coherent population trapping (CPT) or dark state, which is a superposition of atomic and stable molecular states. Such a CPT state facilitates the stimulated Raman adiabatic passage (STIRAP), which utilizes a counterintuitive pulse sequence to coherently convert atoms into stable molecules while avoiding the decoherence associated with the particle loss in the excited state.The technique of STIRAP will be generalized from recent work [H. Y. Ling, H. Pu, and B.Seaman, Phys. Rev. Lett. 93, 250403 (2004)] to the nonlinear systems, where both particle collisions and trap potentials cannot be ignored. The adiabatic condition, which sets the limit to the powers and the widths of the laser pulses for an efficient STIRAP, will be studied in connection with the collective excitation modes of the CPT state. Also studied is the question of how to prepare the system, through quantum state engineering involving laser light, into the nonlinear CPT state in the presence of trap potentials, and the question of how to design more robust STIRAPs capable of efficiently converting atoms into molecules under quite relaxed CPT conditions. The possibility of creating, in the nonlinear system, a coherent superposition of an atomic condensate and a molecular vortex will also be studied - such a superposition represents a new and relatively unexplored quantum state of matter, unique of the coupled atomic-molecular condensate systems. In contrast to two bosonic atoms, which can only form a molecule tightly bound in real space, two fermionic atoms have the additional opportunity of forming a Bardeen-Cooper-Schrieffer (BCS) pair bound in momentum space. This leads to the final area of the proposal to explore the coupled fermionic atomic-molecular condensate systems for studies related to the formation of BCS atom pairs and to the BEC-BCS crossover - the transition from condensates of mainly bound BECmolecules to that of BCS pairs.

本提案的主要目的是探索包含原子和分子物种的多组分冷凝物的物理学，这是物理学研究中发展最快的领域之一。特别令人感兴趣的是双色拉曼光缔合模型（或其Feshbach等效），也称为非线性系统，其中一对稳定的原子要么是光缔合（或磁缔合）成一个不稳定的受激分子，随后被激光场驱动成一个稳定的（基态）分子。非线性系统支持相干种群捕获（CPT）或暗态，这是原子和稳定分子状态的叠加。这种CPT状态有利于受激拉曼绝热通道（STIRAP），该通道利用反直觉的脉冲序列将原子相干地转化为稳定的分子，同时避免了激发态中粒子损失带来的退相干。STIRAP技术将从最近的工作中得到推广[H]。林玉玲，朴慧，b.s seaman，物理学家。在非线性系统中，粒子碰撞和阱势都不能被忽略。绝热条件决定了激光脉冲的功率和宽度，并将与CPT态的集体激发模式联系起来研究。还研究了如何通过涉及激光的量子态工程在存在陷阱电位的情况下将系统制备为非线性CPT状态的问题，以及如何设计更健壮的stirap能够在相当宽松的CPT条件下有效地将原子转化为分子的问题。在非线性系统中创建原子凝聚和分子漩涡的相干叠加的可能性也将被研究-这种叠加代表了一种新的和相对未被探索的物质量子态，这是耦合原子-分子凝聚系统的独特之处。两个玻色子原子在现实空间中只能形成紧密结合的分子，而两个费米子原子在动量空间中有额外的机会形成Bardeen-Cooper-Schrieffer （BCS）对。这就引出了本文的最后一个领域，即探索耦合费米子原子-分子凝聚体系，以研究与BCS原子对的形成和BEC-BCS交叉有关的问题——从主要结合的bec分子凝聚物到BCS对凝聚物的转变。