Electrical identification of single dopant atoms

有没有可能设计一种固态电子器件，其功能基于单个原子的电子占据、轨道状态或自旋状态？一个肯定的答案可能使半导体器件的最终封装成为可能。考虑到这个问题，我们将识别硅纳米结构中的单个掺杂剂原子（故意添加的杂质），然后确定它们的量子力学自旋态的寿命。我们检测掺杂剂原子的主要实验技术是使用单电子晶体管的超灵敏电荷检测。这将使我们能够确定电子是否驻留在随机定位的掺杂剂上，或者掺杂剂是否处于其电离状态。使用无线电频率技术，我们将能够在百万分之一秒内测量这种占用。就其本身而言，这只会告诉我们存在掺杂剂原子（或电荷陷阱），但不知道它的身份。关键是将我们的电荷检测技术与光谱学手段联合收割机结合起来。电子自旋共振是一种合适的技术，能够识别每种杂质原子的独特自旋环境。为了帮助我们，我们将与电子自旋共振专家合作，沃尔特·肖特基研究所的马丁·勃兰特教授。一旦我们确定了掺杂原子，我们将使用电子自旋共振技术，而不是作为光谱技术，而是控制其电子自旋状态。类似的技术已经被用于量子点中的电子-通常被称为“人造原子”的设备。通过这种方式，我们将能够测量硅中单个电子的量子力学自旋寿命。硅中的电子自旋是已知的，从整体测量，与大多数其他材料相比，是长寿命的。由于这种寿命，它们是量子比特的绝佳候选者-量子力学计算机的构建模块。

Is it possible to design a solid-state electronic device with functionality based on the electronic occupancy, orbital-state or spin-state of a single atom? A positive answer could enable the ultimate miniaturisation of semiconductor devices. With this question in mind we will identify individual dopant atoms (intentionally added impurities) in silicon nanostructures and then determine the lifetime of their quantum mechanical spin states.Our main experimental technique to detect dopant atoms is ultra-sensitive charge detection using the single electron transistor. This will enable us to determine whether an electron resides on a randomly positioned dopant, or if the dopant is in its ionised state. Using radio-frequency techniques we will be able to measure this occupancy in a millionth of a second. On its own, this would only tell us that a dopant atom (or charge trap) is present but nothing of its identity. The key is to combine our charge detection technique with a means of spectroscopy. Electron spin resonance is a suitable technique, capable of identifying the unique spin environment of each species of impurity atom. To aid us we will collaborate with an expert in electron spin resonance, Prof. Martin Brandt at Walter Schottky Institute.Once we have identified a dopant atom we will use electron spin resonance not as a spectroscopy technique but to control its electron spin state. A similar technique has already been used in the case of electrons bound in quantum dots - devices often known as 'artificial atoms'. In this way we will be able to measure the quantum mechanical spin lifetimes of a single electron in silicon. Electron spins in silicon are known, from ensemble measurements, to be long-lived when compared to most other materials. Due to this longevity they are excellent candidates to be qubits - the building blocks of a quantum mechanical computer.