Optimal Conditions for Observing Fractional Josephson Effect in Topological Josephson Junctions

Abstract

Topological Josephson junctions (JJs), which contain Majorana bound states, are expected to exhibit 4$\pi$-periodic current-phase relation, thereby resulting in doubled Shapiro steps under microwave irradiation. We performed numerical calculations of dynamical properties of topological JJs using a modified resistively and capacitively shunted junction model and extensively investigated the progressive evolution of Shapiro steps as a function of the junction parameters and microwave power and frequency. Our calculation results indicate that the suppression of odd-integer Shapiro steps, i.e., evidence of the fractional ac Josephson effect, is enhanced significantly by the increase in the junction capacitance and IcRn product as well as the decrease in the microwave frequency even for the same portion of the 4$\pi$-periodic supercurrent. Our study provides the optimal conditions for observing the fractional ac Josephson effect; furthermore, our new model can be used to precisely quantify the topological supercurrent from the experimental data of topological JJs.

20 pages, 5 figures

References in corpus (4)

• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Tunable Supercurrent Through Semiconductor Nanowires
• Adjustable quantum interference oscillations in Sb-doped Bi2Se3 topological insulator nanoribbons
• Geometric dependence of Nb-Bi${}_2$Te${}_3$-Nb topological Josephson junction transport parameters

Cited by in corpus (3)

• Characterization of Shapiro steps in the presence of a 4π-periodic Josephson current
• AC Josephson effect in a gate-tunable Cd${}_3$As${}_2$ nanowire superconducting weak link
• Multiple Andreev reflections in topological insulator nanoribbons