Edge states of topological materials: introduction and applications to Andreev spin qubits

Topological materials [1,2] are currently on the spotlight of quantum science and technology, in view of their exotic physical properties that can be harnessed in a broad spectrum of applications, from nanotechnology to quantum information [3].
In the first part of this Colloquium, I will give a brief introduction to these materials and discuss how peculiar states emerge at their boundaries.
Then, I will focus on their interplay of topological materials with superconductivity and describe a recent proposal of applications [4]: the edge states of a magnetically doped two-dimensional topological insulator contacted with superconductors can be exploited to realize Andreev spin qubits that might outperform current realizations based on nanowires. I will show how these Andreev spin qubit can be optically manipulated, and how quantum logic gates can be designed. Finally, I will address possible experimental realizations.

[1] C. Kane & J. Moore, Topological insulators, Phys. World 24, 32 (2011);
[2] X.L. Qi and S.-C. Zhang, Topological insulators and superconductors, Rev. Mod. Phys. 83, 1057 (2011);
[3] M.J. Gilbert, Topological electronics, Comm. Phys. 4, 70 (2021);
[4]. E. Latini, F. Rossi, F. Dolcini, Andreev spin qubits based on the helical edge states of magnetically doped two-dimensional topological insulators, ArXiv: 2601.22226.

Seminar realized in the framework of the funded projets:
-NEThEQS - Non-equilibrium coherent thermal effects in quantum systems, MUR-PRIN 2022, Grant No. 2022B9P8LN-(PE3)
-TOPMASQ - Topological material platform for the implementation of Andreev spin qubit, 2024 Cascade call project