Quantum transport in 2D topological materials
Topological protection results in coherent quantum states, which can be preserved even in the presence of lattice vibrations, often even at higher temperatures. If the dimension of the material is confined to 2D, such topologically protected states appear in the form of dissipationless edge channels. One example is the 2D topological insulator, namely the quantum spin Hall (QSH) states. If these dissipationless states can be stabilized at higher temperatures, this will open the door to a new era of low-energy consumption electronics. Realizing and detecting these states is one of the main focuses of the QuMat project.
Our approach to realizing the QSH states within QuMat is by MBE growth, a technique that can deposit the material layer by layer with atomic precision. Therefore, high-quality single crystalline thin films will be produced, which potentially should host the desired QSH states at their edges.
In Pillar 3.3, we will focus on the quantum transport measurement in such systems. First, we will characterize the thin films at low temperatures, and show the existence of the ballistic edge channels by measuring the quantized conductance. Then, we will induce superconductivity in the edge channels by means of the proximity effect. This allows us to explore the possibility of constructing the topological superconductivity.
We are looking for a motivated PhD candidate to experimentally study the Josephson effect in topological thin film-based devices. The candidate should have a background in condensed matter physics. While a background in mesoscopic physics or superconductivity would be preferable. In this PhD project, the candidate will learn how to fabricate the (superconducting) nanodevices using electron beam lithography and measure the electronic transport properties of the devices in ultra-low temperature (millikelvin) range in both low and high-frequency regimes.
About Chuan Li
Li’s expertise is in the nanofabrication and transport measurement of mesoscopic devices. She currently focuses on topological nanodevices for quantum computing. She observed the first Higher-order topological states in Bismuth nanowire-based Josephson devices and the topological superconductivity in 3D Dirac semimetals. Li is a recipient of an NWO Veni grant and an NWO Vidi grant. She was awarded the ‘prof. de Winter’ prize of the University of Twente.
About Twente University
The Faculty of Science & Technology (Technische Natuurwetenschappen, TNW) engages some 700 staff members and 2000 students in education and research on the cutting edge of chemical technology, applied physics and biomedical technology. Our fields of application include sustainable energy, process technology and materials science, nanotechnology and technical medicine. As part of a people-first tech university that aims to shape society, individuals and connections, our faculty works together intensively with industrial partners and researchers in the Netherlands and abroad, and conducts extensive research for external commissioning parties and funders. Our research has a high profile both in the Netherlands and internationally and is strengthened by the many young researchers working on innovative projects with as doctoral candidates and post-docs. It has been accommodated in three multidisciplinary UT research institutes: Mesa+ Institute, TechMed Centre and Digital Society Institute.