Probing Andreev and Majorana States with Voltage Pulses

We study the effect of time-resolved voltage pulses applied to normal-insulator-superconductor junctions. With the aid of cutting-edge numerical techniques, we see that applying an alternating train of voltage pulses allows us to manipulate the (Andreev) quasi-bound states that form between the insulator and superconductor. When the superconductor is rendered topologically nontrivial, the presence of a Majorana state gives a zero-bias peak (ZBP) in the conductivity of the junction\footnote{C. Beenakker, Annu. Rev. Condens. Matter Phys., Vol. 4: 113 -136}. We show that by applying different amplitudes/frequencies of voltage pulses we can eliminate or recreate the ZBP and hence probe its Majorana character\footnote{J. Weston et al., Phys. Rev. B \textbf{92}, 020513(R)}. The persistence of this effect in the presence of finite temperature and moderate disorder is promising for the validation of recent experimental results concerning detection of Majoranas in nanowire-superconductor junctions\footnote{V. Mourik et al., Science \textbf{336}, 1003}.