Graphene-based atom chips: a high-performance platform for cold-atom quantum technologies

基于石墨烯的原子芯片：冷原子量子技术的高性能平台

• 批准号: 2602804
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2602804
• 关键词: Graphene; based; atom; chips; performance

The project will develop graphene atom chips that reduce (by orders of magnitude) the atom loss rate and spatial scale of the atom trapping potential, as required for portable chip-based quantum sensors. The chips will enable the creation and manipulation of atomic Bose-Einstein condensates with less stringent vacuum pressure requirements than present devices, thus assisting the scalable industry manufacture of chip-based quantum sensors and clocks.Atom chips use current-carrying microfabricated wires to create a magnetic field and thereby control nearby ultracold atoms. They exhibit robust room-temperature operation and are key components of cold-atom-based quantum sensor/clock technologies1. Existing chips use metallic conductors on bulk substrates. High spatio-temporal noise in the wires, and the large Casimir-Polder attraction of atoms to the substrate, makes the atom clouds fragment and deplete rapidly unless they are held within 5 from the chip. This limits miniaturisation of the chips, the potential landscapes that they produce, and prevents coherent quantum coupling of electrons in the atoms to those in the chips1.This project aims to transform atom-chip performance by exploiting conductors within two-dimensional electron gases in graphene and other 2D materials. Our recent work indicates that these structures will reduce the atom-surface separation and power consumption of the chip by 2 and 5 orders of magnitude respectively and increase the atom cloud's lifetime by 4 orders of magnitude - to minutes - compared with metallic conductors.So far, our work has focused on graphene/boron nitride structures, which are promising for transistors and high-frequency electronics2. Using similar structures for atom chips opens the possibility of dual applications in electronic and cold-atom quantum devices. We now need to develop graphene atom-chip demonstrators, based on established materials such as SiC, to demonstrate the power of two-dimensional materials as a platform for quantum sensors and clocks. Existing SiC-based graphene Hall bars3, developed for quantum resistance metrology, look ideal for proof-of-principle studies and subsequent optimisation. The project will develop atom chips based on graphene and other 2D material multilayers by:1. Calculating atom trap profiles and lifetimes for existing graphene Hall bars, taking into account spatial imperfections and atom loss due to Johnson noise, using Green function models to relate the noise characteristics to the electromagnetic reflection coefficients of the multilayers, tunnelling and 3-body processes.2. Undertaking detailed analysis of experiments on existing SiC-based Hall bars: both their electrical properties and performance as an atom chip trap.3. Simulating the dynamics of trapped atom clouds using Stochastic Projected Gross-Pitaevskii models.4. Designing better samples containing multiple 2D layers to enhance functionality.5. Undertaking theoretical studies of experiments to be performed on these improved samples by collaborators in Germany.

该项目将开发石墨烯原子芯片，根据便携式芯片量子传感器的要求，降低原子损失率和原子捕获势的空间尺度（减少几个数量级）。这些芯片将能够以比现有设备更宽松的真空压力要求来创建和操纵原子玻色-爱因斯坦凝聚体，从而有助于基于芯片的量子传感器和时钟的可扩展工业制造。原子芯片使用载流微加工线来创建磁场，从而控制附近的超冷原子。它们表现出强大的室温运行能力，是基于冷原子的量子传感器/时钟技术的关键组件1。现有芯片在块状基板上使用金属导体。导线中的高时空噪声以及原子对基板的大卡西米尔-波尔德吸引力，使原子云迅速破碎和耗尽，除非它们与芯片的距离保持在 5 以内。这限制了芯片的小型化及其产生的潜在景观，并阻止了原子中的电子与芯片中的电子的相干量子耦合1。该项目旨在通过利用石墨烯和其他二维材料中的二维电子气内的导体来改变原子芯片的性能。我们最近的工作表明，与金属导体相比，这些结构将分别减少芯片的原子表面分离和功耗 2 个和 5 个数量级，并将原子云的寿命增加 4 个数量级（达到分钟）。到目前为止，我们的工作主要集中在石墨烯/氮化硼结构上，这种结构在晶体管和高频电子器件中很有前景。在原子芯片上使用类似的结构开启了在电子和冷原子量子设备中双重应用的可能性。我们现在需要开发基于 SiC 等现有材料的石墨烯原子芯片演示器，以展示二维材料作为量子传感器和时钟平台的强大功能。现有的基于碳化硅的石墨烯霍尔棒3是为量子电阻计量而开发的，看起来非常适合原理验证研究和后续优化。该项目将通过以下方式开发基于石墨烯和其他二维材料多层的原子芯片：1。计算现有石墨烯霍尔棒的原子陷阱轮廓和寿命，考虑空间缺陷和约翰逊噪声引起的原子损失，使用格林函数模型将噪声特性与多层、隧道和三体过程的电磁反射系数联系起来。2．对现有SiC基霍尔棒的实验进行详细分析：它们的电学特性和作为原子芯片陷阱的性能。 3．使用随机投影Gross-Pitaevskii模型模拟捕获原子云的动力学。 4．设计包含多个 2D 层的更好样本以增强功能。5。由德国的合作者对这些改进的样品进行实验的理论研究。