Quantum System Theory Research Team
Principal Investigator
PI Name | Daniel Loss | ||||||||||||||||||
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Degree | Ph.D. | ||||||||||||||||||
Title | Team Leader | ||||||||||||||||||
Brief Resume |
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Outline
Our team works on the quantum theory of condensed matter with a focus on spin and topological phenomena in semiconducting and magnetic nanostructures. In particular, we investigate novel mechanisms and seek new platforms hosting topological or spin phases in solid-state systems, including helical spin texture, topological insulators and topological superconductors, which have potential hosting topological quantum states, such as Majorana fermions and parafermions. Moreover, we also investigate (quasi-)one-dimensional Tomonaga-Luttinger liquid, nuclear spins in semiconductors, many-body effects in low-dimensional systems, (fractional) quantum Hall effect, strongly correlated electron systems, spin-orbit interaction, and quantum transport phenomena.
Research Fields
Theoretical Physics, Quantum Theory of Condensed Matter
Keywords
Strongly correlated electron system
Nanodevice
Spin-orbit interaction
Topological quantum matter
Majorana fermions and parafermions
Results
Majorana Kramers pairs in higher-order topological insulators
Higher order topological insulators are systems which realize the most recent flavor of topological matter. While being insulating in the bulk and on the surface, they host propagating states at the edges (hinges), where two facets meet. We designed a tune-free scheme to realize Kramers pairs of Majorana bound states in higher-order topological insulators with proximity-induced superconductivity.
Our scheme is an experimentally accessible setup, which proposes to use a bismuth wire half-covered by a superconductor. Namely, we find that when two hinges with the same helicity of the wire are in contact to an s-wave superconductor, moderate electron-electron interactions favor the inter-hinge pairing over the intra-hinge pairing, leading to formation of Majorana Kramers pairs. As a result, the proposed scheme does not require a magnetic field or local voltage gates, which is a highly desired property in the quest for topological states.

Left panel: Higher order topological insulator realized using a superconductor (yellow) and a wire (green). Right panel: The phase diagram of the model shown in the Left panel.
Chen-Hsuan Hsu, Peter Stano, Jelena Klinovaja, and Daniel Loss, “Majorana Kramers Pairs in Higher-Order Topological Insulators,” Phys. Rev. Lett. 121, 196801 (2018) © APS
Members
Publications
- C.-H. Hsu, F. Ronetti, P. Stano, J. Klinovaja, and D. Loss
Universal conductance dips and fractional excitations in a two-subband quantum wire
- C.-H. Hsu, P. Stano, Y. Sato, S. Matsuo, S. Tarucha, and D. Loss
Charge transport of a spin-orbit-coupled Luttinger liquid
- P. P. Aseev, P. Marra, P. Stano, J. Klinovaja, and D. Loss
Degeneracy lifting of Majorana bound states due to electron-phonon interactions
- C.-H. Hsu, P. Stano, J. Klinovaja, and D. Loss
Majorana Kramers Pairs in Higher-Order Topological Insulators
- J. Klinovaja, P. Stano, and D. Loss
Topological Floquet Phases in Driven Coupled Rashba Nanowires
2-1 Hirosawa, Wako, Saitama 351-0198 Japan
E-mail:
loss.daniel[at]riken.jp