Electron Self-Organisation and Applications

电子自组织及其应用

• 批准号: EP/J013153/1
• 负责人: Michael Pepper
• 金额: $ 109.45万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FJ013153%2F1
• 关键词: Electron; Self; Organisation; Applications

In most situations electrons in semiconductors can be regarded as free with their energy determined by their total number and their effective mass with the mutual repulsion only slightly modifying this free electron picture. However at low values of carrier concentration the repulsion can dominate the manner in which the electrons diffuse in the solid, a voluminous amount of theory has shown that at sufficiently low temperatures the electrons can arrange themselves into a crystalline ensemble. This is termed a Wigner Crystal, or Wigner Lattice, after Wigner who first predicted such a phenomenon, it has proved rather difficult to observe as the observation of a regular structure is not simple and often the predictions of theory are not found due to the presence of disorder. In one dimension the electrons form a single line and the Wigner Crystal is the trivial case of the electrons seeking a regular periodicity. However, as the confinement weakens, or the electron repulsion increases, so it is possible for the line of electrons to distort as electrons attempt to maximise their separation. In the limit the row splits into two separate rows. The experimental system for such investigations is the electron gas in the GaAs-AlGaAs heterostructure grown by Molecular Beam Epitaxy and the samples are fabricated using high resolution electron beam lithography. In these samples it is possible to control the confinement potential by patterned gates to which voltages are applied, when the samples are sufficiently short electrons drift through ballistically which is without being scattered by random impurities or defects. In this regime the conductance of a one-dimensional wire takes a value 2e2/h where the factor of 2 arises from the spin degeneracy, e is the electron charge and h is Planck's constant. Consequently when a row of electrons splits into 2 rows a conductance of 4e2/h is observed as the ground state. By following the values of conductance as the confinement is changed so the movement of energy levels can be obtained as a function of confinement potential. This has been observed and we call the two rows formed as a result of the electron-electron repulsion the Incipient Wigner Lattice, IWL.Analysis of the results on the movement of energy levels has shown that prior to the formation of the two separate rows a hybridised state is formed in which two electrons are shared between the two rows such that they form a distorted single row. Quantum Mechanics dictates that two electrons shared in this way must have opposite spins and they can be entangled as a consequence of which they each "know" the quantum state the other is in. Entanglement is a remarkable phenomenon in which if the electrons are separated but still entangled then a change of state of one will produce a change in the state of the other. This remarkable property lies at the heart of many proposals for quantum information processing and quantum logic and may give rise to practical consequences not yet envisaged.In this research project we propose to study the IWL and optimise the creation of the hybrid state in which the electrons are entangled. Once this state is completely understood the properties of entangled electrons will be studied by injecting them from the IWL into other quantum structures which essentially form an early quantum integrated circuit. One of the characteristics of entangled electrons is that if two of them are in this state then a variation of the wavelength of them is effectively doubled compared to a single electron. Consequently if we perform an interference experiment there is an immediate difference between the behaviour of entangled and normal electrons, this is the effect which we will explore. The ultimate objective of the work is to develop a method of delivering a stream of entangled electrons and then demonstrate the entanglement in a series of integrated quantum devices with a view to their practical application

在大多数情况下，半导体中的电子可以被视为免费的能量，其能量由它们的总数和有效质量决定，而相互排斥仅略微改变了这种自由电子图片。然而，在低载体浓度值下，排斥可以主导电子在固体中扩散的方式，大量理论表明，在足够低的温度下，电子可以将自己安排成晶体集合。这被称为Wigner Crystal或Wigner晶格，其首先预测了这种现象的Wigner，事实证明，它很难观察到，因为对常规结构的观察并不简单，并且通常由于存在障碍而没有发现理论的预测。在一个维度上，电子形成单线，wigner晶体是寻求正常周期性的电子的微不足道的情况。然而，随着限制的削弱或电子排斥的增加，电子线可能会随着电子试图最大程度地分离而变形。在限制中，行分成两个单独的行。进行此类研究的实验系统是通过分子束外延生长的GAAS-ALGAA异质结构中的电子气体和样品使用高分辨率电子束光刻制造。在这些样品中，有可能通过施加电压的图案门，当样品充分短暂的电子在弹道上漂移而不会被随机杂质或缺陷分散时，可以控制施加电压的限制电位。在此方向上，一维线的电导率为2e2/h，其中2的因子来自自旋退化，E是电子电荷，H是Planck的常数。因此，当一排电子分裂为2行时，将4E2/h的电导视为基态。通过遵循导电值随着限制的变化，因此可以将能级的运动作为限制潜力获得。已经观察到了这一点，我们称这两排是由于电子 - 电子击退而形成的，初期的Wigner晶格IWL。对能量水平运动的结果进行的分析表明，在形成两个单独的行之前，杂交状态形成了两个电子，在两个rows之间共享了两个rows，它们是在形成单个distort andort disted and disted and disted and disted andort and disted and disted and disted ardort and disted ardort ardort row row的。量子力学指出，以这种方式共享的两个电子必须具有相反的旋转，并且由于他们每个人都“知道”对方所处的量子状态。这种非凡的特性是许多关于量子信息处理和量子逻辑的建议的核心，并可能引起尚未设想的实际后果。在这项研究项目中，我们建议研究IWL并优化电子纠缠的混合状态的创建。一旦完全理解了该状态，将通过将IWL从IWL注入其他量子结构，从而研究它们的纠缠电子的性能，这些量子结构基本上形成了早期量子整合电路。纠缠电子的特征之一是，如果其中两个处于这种状态，那么与单个电子相比，它们的波长的变化有效地翻了一番。因此，如果我们执行干扰实验，纠缠和正常电子的行为之间会有直接的差异，这就是我们将要探索的效果。这项工作的最终目标是开发一种传递纠缠电子流的方法，然后在一系列集成的量子设备中演示纠缠