Non-Abelian quantum order in spin-orbit-coupled semiconductors: Search for topological Majorana particles in solid-state systems

By J. Sau, S. Tewari, R. Lutchyn, T. Stanescu. 2010

295 citations recorded by the source corpus.

We show that an ordinary semiconducting thin film with spin-orbit coupling can, under ap- propriate circumstances, be in a quantum topologically ordered state supporting exotic Majorana excitations which follow non-Abelian statistics. The key to the quantum topological order is the coexistence of spin-orbit coupling with proximity-induced s-wave superconductivity and an externally-induced Zeeman coupling of the spins. For the Zeeman coupling below a critical value, the system is a non-topological (proximity-induced) s-wave superconductor. However, for a range of Zeeman coupling above the critical value, the lowest energy excited state inside a vortex is a zero-energy Majorana fermion state. The system, thus, has entered into a non-Abelian s-wave superconducting state via a topological quantum phase transition (TQPT) tuned by the Zeeman coupling. In the one-dimensional version of the same structure and for the Zeeman coupling above the critical value, there are localized Majorana zero-energy modes at the two ends of a semiconducting quantum nanowire. In this case, the Zeeman coupling can be induced more easily by an external magnetic field parallel to the wire, obviating the need for a magnetic insulator. We show that, despite the fact that the superconducting pair potential in the nanowire is explicitly s-wave, tunneling of electrons to the ends of the wire reveals a pronounced zero-bias peak. Such a peak is absent when the Zeeman coupling is below its critical value, i.e., the nanowire is in the non-topological s-wave superconducting state. We argue that the observation of this zero-bias tunneling peak in the semiconductor nanowire is possibly the simplest and clearest experiment proposed so far to unambiguously detect a Majorana fermion mode in a condensed matter system.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/58e1daec8b55d1c52edf7235a2ba6864dd5d7439

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Citations in the corpus

Observation of the fractional ac Josephson effect: the signature of Majorana particles (2012, background): “What are the experimental signatures of Majorana particles? Majorana particles come in pairs, and zero energy Andreev end-modes localized at the ends of a wire can be probed in tunneling experiments[11, 21, 22].”
Two-dimensional epitaxial superconductor-semiconductor heterostructures: A platform for topological superconducting networks (2015, background): “Narrow bandgap semiconductors such as InAs and InSb are natural choices for the Sm component due to large g factors and strong SOC, which are important for the stability of an emergent topological phase in S-Sm heterostructures, with the topological gap proportional to the SOC strength [23].”