Single Electron Manipulation in Silicon Nano-Wire for Quantum Technologies

Quantum Technology is considered to achieve innovation in secure communication, high performance computing, simulation, sensor, and metrology. However, the manufacturing challenges must be overcome to integrate quantum structures for real industrial applications, because of the extremely fragile character of quantum states subject to environmental disturbances like line-edge-roughness, thickness-non-uniformity, random dopant fluctuations, and interfacial defects. In this project, we will develop a manufacturing process technology of silicon nano-wire and manipulate single electron for quantum technologies.

The primary goal of this project is to understand the transport mechanism in silicon nano-wire at the single electron level. This will be important for the application to new definition of the current. A ‘quantum’ redefinition of the SI system of physical units is presently under discussion, based on the fundamental physical constants of nature. The quantum hall resistance and the AC Josephson voltage effects provide accurate conversion from frequency-to-voltage and voltage-to-current via fundamental constants. As the SI electrical base unit is actually the current unit [Ampere], a further device is required, namely a frequency to current converter driven by an accurate timing signal. The single-electron pump is considered to be the most promising candidate for such a current standard, since the current can be simply expressed as the elementary charge multiplied by the frequency.

This project involves three industrial partners, NPL (London), NTT (Japan) and RIKEN (Japan). The PhD student will also be supervised in the these world-leading industrial environments. We are planning to prepare the internship opportunities in Japan with full supports for travel fees and stipend. The funding is supported by the EU project, EMPIR, and Lloyds Register Foundation (LRF). The student will also attend the international workshop organized by the LRF ICON project.

The purpose of this project is to achieve the better performance of the Si based single-electron-pumps as a current standard. There are potential advantages of Si devices over GaAs on the nano-meter scale, for instance access to larger charging energy by the formation of a smaller quantum dot. This should enhance the robustness of the quantisation of trapped electrons against thermal agitation and other error mechanisms. Simultaneous operation of many parallel devices may also be possible through manufacturing technologies developed. Further study of Si systems fabricated by well-controlled manufacturing process in the University of Southampton and the state-of-the-art measurement techniques developed at NPL and NTT is highly desirable.

We will also investigate about the future application of silicon nano-wire for quantum information processing. Silicon is one of the most pristine materials for a solid-state device, and it is suitable for mass production. Excellent cryogenic measurement facilities are available at RIKEN and the Tokyo Institute of Technology, where the PhD student will investigate the device for fundamental understanding the trapping/de-trapping process of single electron, which is also important for establishing reliabilities in LSI circuitry. We will address increased reliability problems on the failure of transistors in a scaled transistor due to random telegraph noises caused by single electron.