Tuning short- and long-range interactions in an ultracold chromium gas

调节超冷铬气体中的短程和长程相互作用

• 批准号: 5407210
• 负责人: Professor Dr. Tilman Pfau
• 金额: --
• 依托单位: 5. Physikalisches Institut
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2003
• 资助国家: 德国
• 起止时间: 2002-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5407210?language=en
• 关键词: Tuning; short; long; range; interactions

Ordered dipolar systems are well known, e.g. in the solid as ferromagnets and in the liquid phase as ferrofluids. Dipolar quantum gases are expected to exhibit a rich variety of new phenomena related to condensed matter physics and quantum optics. The goal of the proposed project is the creation and characterisation of degenerate bosonic and fermionic quantum gases using a dilute gas of chromium atoms. Due to the large magnetic moment of chromium, the dipole-dipole interaction plays an important role in this system. By cooling chromium down into the quantum degenerate regime, we will be able to observe the influence of the dipole-dipole interaction while so far only the effects of the s-wave contact interaction could be studied in e.g. rubidium or sodium Bose-Einstein condensates. Our system offers the possibility to change the dipole-dipole interaction by using time-varying magnetic fields and also the contact interaction by using Feshbach resonances. This allows us to independently control both interactions and to investigate their interplay on the properties of a quantum gas. We will investigate the dipolar order in the groundstate of bosonic and fermionic quantum degenerate gases. While the contact interaction is eqivalent to a Kerr nonlinearity in classical optics, which has lead to the observation of matter-wave solitons and vortices, there is no equivalent to the long-range interaction in classical optics. Thus, new phenomena are expected to emerge for a dipolar matter wave, which have no parallels in light optics. One example could be the generation of quantum correlations over a distance.

有序偶极系统是众所周知的，例如在固体中作为铁磁体，在液相中作为铁磁流体。偶极量子气体有望展现出与凝聚态物理和量子光学相关的丰富多样的新现象。该计划的目标是利用铬原子的稀释气体创造并表征简并玻色子和费米子量子气体。由于铬具有较大的磁矩，偶极-偶极相互作用在该体系中起着重要的作用。通过将铬冷却到量子简并态，我们将能够观察到偶极子-偶极子相互作用的影响，而到目前为止，只有s波接触相互作用的影响可以在例如铷或钠的玻色-爱因斯坦凝聚体中研究。我们的系统提供了利用时变磁场改变偶极-偶极相互作用的可能性，也提供了利用费什巴赫共振改变接触相互作用的可能性。这使我们能够独立地控制这两种相互作用，并研究它们对量子气体性质的相互作用。我们将研究玻色子和费米子量子简并气体基态中的偶极序。在经典光学中，接触相互作用相当于克尔非线性，这导致了对物质波孤子和涡旋的观测，但在经典光学中没有与远距离相互作用等效的相互作用。因此，对偶极物质波的新现象有望出现，这在光光学中没有相似之处。一个例子可能是远距离量子相关的产生。