Quantum mechanical simulation of superconducting qubits

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Quantum computers (QC) have an enormous impact on many areas of our life and for this reason they are one of the most heavily researched topics not only in academia but also in the industry. Companies such as Honeywell, IBM and Google are using different technologies to create qubits.One of the most promising technology is superconducting qubits made from Josephson Junctions (JJ). JJ are made for a superconducting material, e.g. Al and tunnel junctions made from a thin layer of non-superconducting materials, e.g. AlOx (in an ideal case x=1.5). While there is constant improvement of the circuit designs, error corrections, reproducibility and reliability of the qubits, there is still significant knowledge gap in relevant material science. For example, the growth process of AlOx on top of Al is not well understood which is crucial to be able to fabricate uniform, without defects and surface roughness JJ. Any imperfections of the JJ, such as charges trapped in the oxide, dangling bonds and different stoichiometry in AlOx (x can be a number between 1.3 and 1.8) will produce different tunnelling current and hence different qubit behaviour. The variability of the qubit's behaviour makes the design of the circuit much harder and increases the errors in the measurements and decreases the coherent times.The main aim of this project is to develop a unique computational framework which will be able to simulate realistic size superconducting qubits. Here we will investigate Al/AlOx/Al interfaces (Josephson Junctions) as qubits. The simulation framework will combine various quantum mechanical methods which will allow us to simulate not only materials growth of Al/AlOx/Al interfaces but also the variability of the tunnelling current due to trap charges and defects. Such computational framework is the most cost effective and time saving approach in order to significantly improve the reliability, reproducibility and decrease variability in superconducting qubits.This work is based on close collaboration with the group of Prof Martin Weides, the leading expert in the field. The vision is to simulate various architectures and types of devices in order to evaluate and to predict the critical design parameters for the fabrication process.The ideal candidate will have good computational skills and a background in engineering, physics or chemistry. Knowledge of computational methods, such as Density Functional Theory (DFT) and numerical methods, is highly advantageous but not mandatory. Programming skills are not required but will be beneficial. Also, the candidate must be self-motivated, interested in conducting interdisciplinary computational and theoretical research and to have good interpersonal skills.The student will be part of the Device Modelling Group in the University of Glasgow, which is perhaps the largest specialised semiconductor device group in academia worldwide. The group is the world leader in 3D simulations of advanced CMOS devices that include different sources of statistical variability. The group is listed among the five leading Electronic Materials and Devices Centres according to EPSRC funding in the ICT Programme Landscape (2008) documents.