Quantum devices: engineering electronic coherence in nanostructures

我们的团队构建和测量纳米级电子器件，其几何形状旨在从传输（电阻）测量中产生新的物理学。 我们的实验是在低温下进行的-通常小于1开尔文-其中电子特性由相干量子力学效应主导。在这个极限下，从实验室设备发送到被测设备的信号提供了对量子力学自由度的原位控制。我们提出了一个三管齐下的方法，我们的研究在未来5年。第一个是建立在我们过去5年最成功的一组实验基础上的;第二个是继续我们小组向凝聚态物理学中最热门的新领域之一的扩展;第三个是利用我们小组的独特地位进入一个新的方向，具有巨大的潜在回报： 1. 我们最近发现了一种称为弹道自旋共振的新现象，其中自旋-轨道相互作用耦合到几何共振，从而在半导体（GaAs）器件中产生快速自旋旋转。到目前为止，这些自旋旋转只能通过快速有效的自旋弛豫速率来检测，但在这里，我们建议利用这种现象来实现快速和可调的自旋旋转。 2.尽管在被称为石墨烯的碳单原子层中普遍预测长自旋相干时间，但从实验的角度来看，对实际样品中电子和空穴自旋的行为知之甚少。我们的团队在这一领域取得了进展，展示了石墨烯中第一个基于干涉的自旋电流测量。 我们将大大扩展这一研究领域，应用我们现有的GaAs自旋测量专业知识来研究石墨烯中的自旋相干性。 3. 世界各地的研究小组只是在去年才认识到表面原子对石墨烯电子性质的影响。 在这里，我们建议通过将特定的原子沉积到石墨烯中和石墨烯上，以有意的方式显着改变石墨烯的特性。

Our group builds and measures nanoscale electronic devices whose geometries are designed to yield new physics from a transport (resistance) measurement. Our experiments are performed at low temperature--typically less than 1 Kelvin--where electronic properties are dominated by coherent quantum mechanical effects. In this limit, signals sent from laboratory equipment to the device under test provide in situ control over quantum mechanical degrees of freedom. We propose a three-pronged approach to our research in the coming 5 years. The first builds off of our most successful set of experiments from the past 5 years; the second continues our group's expansion into one of the hottest new fields in condensed matter physics; the third takes advantage of our group's unique position to move into a new direction with great potential payoff: 1. We recently discovered a new phenomenon called ballistic spin resonance, in which spin-orbit interaction couples to geometric resonances to give fast spin rotations in a semiconductor (GaAs) device. Until now these spin rotations were detected only by a fast effective spin relaxation rate, but here we propose to exploit this this phenomenon for fast and tunable spin rotations as well. 2. Despite widespread predictions for long spin coherence times in single atomic layers of carbon known as graphene, very little is known from an experimental point of view about the behaviour of electron and hole spins in a practical sample. Our group made inroads into this area, demonstrating the first interference-based spin current measurement in graphene. We will greatly expand this area of research, applying our existing expertise in GaAs spin measurements to study spin coherence in graphene. 3. Groups around the world are only within the last year recognizing the influence that surface atoms can have on graphene's electronic properties. Here we propose to dramatically change graphene's properties in an intentional way by depositing particular atoms into and onto the graphene.