Advanced materials

Quantum computing is becoming an important topic in which major players, such as IBM, Google, Intel or Microsoft are getting involved. The objective of the quantum computer is not simply to go faster than the traditional computer. It will be used to solve problems inaccessible to traditional computers. It will be to treat problems of exponential nature whose complexity increases exponentially with the quantity of data to be treated. The basic brick of quantum computers are the Qubits. To date, several avenues are being explored for the fabrication of these qubits, among the most cited: superconductors, trapped ions, CMOS, topological insulators, diamond cavities. The focus of this collaboration is based on the most promising avenue of superconductors. The growth of these advanced materials, such as superconductors, is carried out at very low temperature (cryogenic temperature) on topological insulator or on type III-V structures having been previously epitaxied at high temperature.

During the last 10 years, research on topological materials has attracted particular attention from the scientific community due to their outstanding properties. In such systems, the electronic surface states are Topologically protected from their environment, which makes them an ideal basis for the realization of Quantum devices. In their pioneering paper, Kane and Mele proposed the existence of Topological Insulators (TIs)1, which exhibit an insulating core and topologically protected metallic surface states. The first experiments demonstrating these properties are based on 2D layers of HgTe2 and 3D crystals of bismuth antimonide3.

Despite advances, their integration on industrial standards (Silicon, GaAs) remains challenging but represent a key enabler for future Spintronic and Quantum Computing devices. Here we study the thin layer growth of BiwSbxTeySez Topological Insulators on industrial wafers and their integration with cryogenic grown Superconductors.

1. Kane, C. L. & Mele, E. J. $Z_2$ Topological Order and the Quantum Spin Hall Effect. Phys Rev Lett 95, 146802 (2005).

2. Bernevig, B. A., Hughes, T. L. & Zhang, S.-C. Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells. Science 314, 1757 (2006).

3. Hsieh, D. et al. A topological Dirac insulator in a quantum spin Hall phase. Nature 452, 970–974 (2008).