Nano-optical detection of novel phases in ultracold Fermi gases

超冷费米气体中新相的纳米光学检测

• 批准号: EP/H043446/1
• 负责人: Stefan Eriksson
• 金额: $ 13.62万
• 依托单位: Swansea University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FH043446%2F1
• 关键词: Nano; optical; detection; novel; phases

Frontier areas of physics operate at extreme conditions. Researchers routinely laser cool and trap neutral atoms at temperatures around a few billionths of a degree above absolute zero. The collective behaviour of atoms in this ultracold regime is surprising and very different from common everyday experiences. The atoms may e.g. flow with low shear viscosity in a superfluid phase. Researchers can nowadays tune the interactions in the ultracold quantum gas to become so strong that the detailed nature of the interaction potential is less important. In this unitary regime physicists are discovering that cold atoms have features in common with other strongly interacting systems such as condensed matter and even baryonic matter despite several tens of orders of magnitude difference in density. Specific areas of interest to both atomic and condensed matter physics are already identified with phenomena relating to superconductivity perhaps the best known example. There are increasingly clear hints of a connection to baryonic matter. For example, at temperatures of around 2 trillion Kelvin previously only reached moments after the Big Bang researchers find that the constituent quarks and gluons of baryonic matter make a transition to a plasma which also flows with low shear viscosity. At densities found in neutron stars quantum field theories predict that superfluid and superconducting phases of nuclear or even quark matter may exist. The connection between ultracold atoms at the unitary limit and other strongly interacting systems is intriguing and the rapid experimental cycle of cold atoms experiments could help elucidate phenomena in diverse areas of physics. In particular the nature of phase transitions in strongly interacting systems in general is still not well understood, and the tuneability of the atomic interactions makes this area an ideal candidate for further study. An intense effort is now underway to exploit the connection between cold atoms and condensed matter and there is growing interest to explore the connection to nuclear matter. Unfortunately, the standard detection techniques currently used in ultracold atoms experiments do not reveal details of exotic new quantum phases of interest. In this project we aim to construct an entirely new atom detector which will resolve this problem by detecting correlations in the cold gas at the single atom level. Achieving our goal requires us to work at another extreme; optics at the nanometre scale. We will make optical fibres with diameters less than the optical wavelength (a few hundred nanometres). Astonishingly, most of the light that is guided by such fibres propagates outside the fibre itself! This feature allows us to detect the presence of a single atom simply by observing whether the nanofibre photon has been absorbed by the nearby atom. The small mode size will ultimately result in an unprecedented optical resolution. In parallel we will create a trapped ultracold degenerate Fermi gas with resonant atomic collisions so that the gas becomes strongly interacting at unitarity. We plan to incorporate an array of nanofibre detectors in the experiment so that we can test how individual atoms released from the trap are correlated. We will be able to see pairwise correlated atoms relating to superconductivity in solids, but also signatures of quantum phases relating to nuclear matter and its constituents. At the end of the project we will be equipped with new tools to tackle questions of interest to both quantum field theorists and cold atom experimentalists. We will also try to further clarify the connection to quark matter.The future applicability of the nanofibre detector extends to quantum information science where controlled atom-photon interactions are important. The nanofibre can also become a sensitive detector of complex molecules and larger nanostructures. In the long term the detector may find applications in biosensing and nanotechnology.

物理学的前沿领域在极端条件下运作。研究人员通常在绝对零度以上数十亿分之一度的温度下用激光冷却和捕获中性原子。原子在这种超冷状态下的集体行为令人惊讶，与普通的日常经验非常不同。原子可以例如在超流相中以低剪切粘度流动。研究人员现在可以调整超冷量子气体中的相互作用，使其变得如此强大，以至于相互作用势的详细性质不那么重要。在这个幺正体系中，物理学家发现冷原子与其他强相互作用系统（如凝聚态物质甚至重子物质）具有共同的特征，尽管它们的密度相差几十个数量级。原子物理和凝聚态物理都感兴趣的特定领域已经与超导现象有关，也许是最著名的例子。有越来越多的迹象表明它与重子物质有关。例如，在大约2万亿开尔文的温度下，研究人员发现，在大爆炸之后的瞬间，重子物质的组成夸克和胶子转变为等离子体，这种等离子体也以低剪切粘度流动。在中子星的密度下，量子场论预言核物质甚至夸克物质的超流和超导相可能存在。酉极限下的超冷原子与其他强相互作用系统之间的联系是有趣的，冷原子实验的快速实验周期可以帮助阐明物理学不同领域的现象。特别是在强相互作用系统中的相变的性质一般还没有得到很好的理解，原子相互作用的调谐使这一领域成为进一步研究的理想候选者。人们正在努力探索冷原子和凝聚态物质之间的联系，并且对探索与核物质的联系越来越感兴趣。不幸的是，目前在超冷原子实验中使用的标准检测技术并不能揭示感兴趣的奇异新量子相的细节。在这个项目中，我们的目标是构建一个全新的原子探测器，它将通过在单原子水平上探测冷气体中的相关性来解决这个问题。实现我们的目标需要我们在另一个极端工作;纳米尺度的光学。我们将制造直径小于光波长（几百纳米）的光纤。令人惊讶的是，大多数由这种纤维引导的光在纤维本身之外传播！这一特性使我们能够通过观察纳米纤维光子是否被附近的原子吸收来检测单个原子的存在。小的模式尺寸将最终导致前所未有的光学分辨率。同时，我们将创建一个被困的超冷简并费米气体与共振原子碰撞，使气体成为强烈的相互作用在幺正性。我们计划在实验中加入一系列纳米纤维探测器，这样我们就可以测试从陷阱中释放出来的单个原子是如何相互关联的。我们将能够看到与固体超导性有关的成对相关原子，以及与核物质及其成分有关的量子相的特征。在项目结束时，我们将配备新的工具来解决量子场论学家和冷原子实验学家感兴趣的问题。我们也将尝试进一步澄清与夸克物质的联系。纳米纤维探测器的未来适用性扩展到量子信息科学，其中受控的原子-光子相互作用是重要的。纳米纤维还可以成为复杂分子和更大纳米结构的灵敏检测器。从长远来看，这种探测器可能会在生物传感和纳米技术中得到应用。

项目成果

Ultracold Atoms in a Hybrid Magnetic and Optical Trap for Atom-Light Interactions with a Tapered Optical Nanofibre

混合磁光陷阱中的超冷原子与锥形光学纳米纤维的原子光相互作用

• 发表时间: 2017
• 作者: Jenkins R A

Towards a BEC-ONF Quantum Interface

迈向 BEC-ONF 量子接口

• 发表时间: 2017
• 作者: Alampounti C A

Optical Nanofibres

光学纳米纤维

• 发表时间: 2013
• 作者: Evans, C.

Towards the Production of a Quantum Gas Near a Tapered Optical Nanofibre

致力于在锥形光学纳米纤维附近生产量子气体

• 发表时间: 2015
• 作者: JENKINS, R.

Magnetically trapped atoms in the vicinity of an optical nanofibre

光学纳米纤维附近的磁俘获原子

• DOI: 10.1007/s00340-020-7418-2
• 发表时间: 2020
• 期刊: Applied Physics B
• 作者: Alampounti A