Electrical identification of single dopant atoms

有没有可能设计一种具有基于单个原子的电子占有率、轨道态或自旋态的功能的固态电子设备？一个肯定的答案可能会使半导体设备最终实现小型化。考虑到这个问题，我们将识别硅纳米结构中的单个掺杂原子(有意添加的杂质)，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位置的掺杂剂上，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一占有率。就其本身而言，这只会告诉我们存在一个掺杂原子(或电荷陷阱)，但并不能说明它的身份。关键是将我们的电荷检测技术与光谱学手段相结合。电子自旋共振是一种合适的技术，能够识别每种杂质原子独特的自旋环境。为了帮助我们，我们将与沃尔特·肖特基研究所的电子自旋共振专家马丁·勃兰特教授合作。一旦我们确定了掺杂原子，我们将使用电子自旋共振不是作为一种光谱技术，而是控制它的电子自旋状态。一种类似的技术已经被用来处理束缚在量子点中的电子。量子点是一种通常被称为“人造原子”的装置。通过这种方式，我们将能够测量硅中单电子的量子力学自旋寿命。根据系综测量，与大多数其他材料相比，硅中的电子自旋具有较长的寿命。由于这种寿命，它们是成为量子比特的极佳候选者--量子比特是量子力学计算机的组成部分。

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.