Mishmash, Ryan; Aasen, David; Higginbotham, Andrew PISTA ; Alicea, Jason
Recent experiments have produced mounting evidence of Majorana zero modes in nanowire-superconductor hybrids. Signatures of an expected topological phase transition accompanying the onset of these modes nevertheless remain elusive. We investigate a fundamental question concerning this issue: Do well-formed Majorana modes necessarily entail a sharp phase transition in these setups? Assuming reasonable parameters, we argue that finite-size effects can dramatically smooth this putative transition into a crossover, even in systems large enough to support well-localized Majorana modes. We propose overcoming such finite-size effects by examining the behavior of low-lying excited states through tunneling spectroscopy. In particular, the excited-state energies exhibit characteristic field and density dependence, and scaling with system size, that expose an approaching topological phase transition. We suggest several experiments for extracting the predicted behavior. As a useful byproduct, the protocols also allow one to measure the wire's spin-orbit coupling directly in its superconducting environment.
Physical Review B
Mishmash R, Aasen D, Higginbotham AP, Alicea J. Approaching a topological phase transition in Majorana nanowires. Physical Review B. 2016;93(24). doi:10.1103/PhysRevB.93.245404
Mishmash, R., Aasen, D., Higginbotham, A. P., & Alicea, J. (2016). Approaching a topological phase transition in Majorana nanowires. Physical Review B. American Physical Society. https://doi.org/10.1103/PhysRevB.93.245404
Mishmash, Ryan, David Aasen, Andrew P Higginbotham, and Jason Alicea. “Approaching a Topological Phase Transition in Majorana Nanowires.” Physical Review B. American Physical Society, 2016. https://doi.org/10.1103/PhysRevB.93.245404.
R. Mishmash, D. Aasen, A. P. Higginbotham, and J. Alicea, “Approaching a topological phase transition in Majorana nanowires,” Physical Review B, vol. 93, no. 24. American Physical Society, 2016.
Mishmash R, Aasen D, Higginbotham AP, Alicea J. 2016. Approaching a topological phase transition in Majorana nanowires. Physical Review B. 93(24), 245404.
Mishmash, Ryan, et al. “Approaching a Topological Phase Transition in Majorana Nanowires.” Physical Review B, vol. 93, no. 24, 245404, American Physical Society, 2016, doi:10.1103/PhysRevB.93.245404.