Atomistic transport in topological-insulator nanowires and nanoribbons for quantum-computing applications

Leuven - PhD
More than two weeks ago

Explore unchartered frontiers of Physics and new computing paradigms with a brand-new class of materials and devices featuring intriguing new quantum states of matters, while learning to use and define state-of-the-art quantum transport atomistic tools and methods.


Topological insulators (TI) (the topic of the 2016 Nobel prize of Physics) are a recent class of materials featuring intriguing new quantum states of matters. The appearance of topologically protected states at the surface of nanowires or at the edge of 2-D made of TI materials allows, for instance, for the observation of the long predicted Majorana fermions. Owing to their long coherence time, Majorana states in TI are considered as very promising candidate to build quantum bits (qbits), the basic blocks to build a quantum computer.


The proposed work relies on the exploration of transport properties of nanowire or devices made of TI materials (e.g. Bi2Se3) using atomistic simulation methods. The atomistic description should be done in a localized DFT basis (Ab Initio). The localized orbital DFT description can for instance be obtained using the Maximally localized Wannier Function that is compatible with our state-of-the-art NEGF atomistic solver. A tight-binding model fitted to DFT could also be envisioned, if needed, for numerical efficiency. As the computational burden of such atomistic simulations is particularly heavy, the simulation speed will be improved, by several orders of magnitude, using atomistic acceleration (mode-space NEGF) techniques that we have pioneered. Using the mode-space technique, we have recently demonstrated the atomistic transport simulation of a III-V nanowire with over a million atoms (more than 100× larger than what can be simulated with traditional techniques) and a diameter of 18.2 nm.


In this thesis, you will explore the properties of new TI materials in nanoribbon and nanowire form. You will build using DFT, the supercell elements needed for the device simulations. You will learn to use and expand the most advanced quantum transport atomistic tools and methods in order to simulate TI materials and Majorana fermion quasi-particle states. You will investigate the fundamental physics and performance of innovative TI devices with as possible target application, qbits for a topological quantum computer. You will learn and benefit from the support from modeling experts in the field. Possibility to interact with experimentalists working on Quantum computing is also available at imec.



Required background: Physical/Electrical/Electronic/Material Engineering or Physics


Type of work: ~50% NEGF device physics and simulations, ~30% quantum transport code development, ~20% DFT simulation of new material (2D, TI).

Supervisor: Michel Houssa, Aryan Afzalian

Daily advisor: Aryan Afzalian

The reference code for this position is 1812-45. Mention this reference code on your application form.


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