Abstract
Possible signatures of “Majorana end states” are discussed by combining information extracted from subgap Cooper pair transport and transport of heat by excited quasiparticles above the gap across a thermally biased Josephson junction setup formed out of a one-dimensional (1D) topological superconductor hosting Majorana end states. We show that the presence of Majorana end states results in two sets of testable relations: (i) the ratios between the various multiterminal thermal conductances is independent of the Josephson phase bias, and (ii) the phase independence of the ratios of “ratios of the phase derivative of multiterminal thermal conductance and the corresponding Josephson current”, in a three-terminal setup. We contrast out findings with a Josephson junction setup composed of a 1D topological superconductor hosting “Andreev type end states” and show that they violate the above-mentioned relations. We also discuss how the presence of nonequilibrium noise in thermal current influences our predictions.
Abstract
It is known that Josephson junction (JJ) hosting scattering centers with energy-dependent scattering amplitudes, which breaks the ω→−ω symmetry (where ω is the excitation energy of electron about the Fermi level) exhibits finite thermoelectric response. In contrast, here we show that even in a ballistic JJ this symmetry is broken and it leads to a nonzero thermal-bias induced charge current above the gap, when the junction length is of the order of coherence length of the superconductor and the corresponding response confirms to the universal sinusoidal dependence on ϕ12, where ϕ12 is the superconducting phase bias. In presence of multiple scatterers in the junction region, we have numerically shown that the sign of the even-in-ϕ12 part of the this response fluctuates violently from one disorder configuration to another hence averaging to vanishingly small values while the odd part tends towards the universal sinusoidal dependence on ϕ12 as we approach the large disorder limit under disorder averaging.
Abstract
A hybrid setup consisting of a superconductivity-proximitized quantum spin Hall insulator and a quantum anomalous Hall (QAH) insulator is proposed for chiral injection of electrons into the Majorana bound state (MBS). An unexplored region of the phase space involving the Zeeman-field-induced boost of the helical edge state is then proposed for the detection of the MBS. Two-dimensional transport simulations of our proposed setup are compared with the corresponding setup in the absence of the QAH region, when moderate potential and magnetic disorder are included. The remarkable contrast between the two results demonstrates the possibility for an unprecedented immunity from disorder-induced masking of the MBS detection in our proposed setup.