Photon-assisted tunneling through a topological superconductor with Majorana bound states

Abstract

Employing the Keldysh Nonequilibrium Green’s function method, we investigate time-dependent transport through a topological superconductor with Majorana bound states in the presence of a high frequency microwave field. It is found that Majorana bound states driven by photon-assisted tunneling can absorb(emit) photons and the resulting photon-assisted tunneling side band peaks can split the Majorana bound state that then appears at non-zero bias. This splitting breaks from the current opinion that Majorana bound states appear only at zero bias and thus provides a new experimental method for detecting Majorana bound states in the Non-zero-energy mode. We not only demonstrate that the photon-assisted tunneling side band peaks are due to Non-zero-energy Majorana bound states, but also that the height of the photon-assisted tunneling side band peaks is related to the intensity of the microwave field. It is further shown that the time-varying conductance induced by the Majorana bound states shows negative values for a certain period of time, which corresponds to a manifestation of the phase coherent time-varying behavior in mesoscopic systems.

Photon-Assisted Transport Through a Quantum Dot Side-Coupled to Majorana Bound States

“…where c † kα (c kα ) creates (annihilates) an electron of momentum k, energy ε kα in the lead α = L, R. For the QD, [21]. Here, we have assumed that the photon field with strength d and frequency ω p is applied only on the QD and the leads are free from its irradiation, and then only the dot's energy level is time-varying.…”

“…A vast of experimental works have been devoted to the detection of MBSs, relying on the signatures probably induced by the MBSs, including the 4π periodic Josephson current-phase in junctions between topological superconductors [13], half-integer conductance plateau at the coercive field in a hybrid structure composing of topological superconductors and topological quantum anomalous Hall insulator [6], tunneling spectroscopy using the Rashba nanowires coupled to the bulk s-wave superconductors [10], zero-bias of the differential conductance at the edges of the wires [14,15], the non-locality [16][17][18][19] and Kondo effect [20] influenced by MBSs. Since the above signatures can also be brought about by other mechanisms, some alternative schemes then have been continually put forward, such as the optical detection ones [21][22][23]. In [21], the authors found that the MBSs will absorb(emit) photons and result in photon-assisted tunneling side band peaks.…”

“…Since the above signatures can also be brought about by other mechanisms, some alternative schemes then have been continually put forward, such as the optical detection ones [21][22][23]. In [21], the authors found that the MBSs will absorb(emit) photons and result in photon-assisted tunneling side band peaks. This process can split the MBSs and then induces non-zero MBSs mode, providing another detection scheme for the existence of MBSs which is quite different the currently adopted ones concerning zero-energy MBSs mode.…”

“…Quite different from the above optical detection schemes for the MBSs, we propose to insert a QD, which is coupled to a topological nanowire hosting MBSs at its two ends, between two normal metal leads. One of the advantages of our system, as compared to the ones in [21,22], is that the transport processes occur between the leads and the QD. The electrons will not enter into the MBSs mode existed in the topological superconductor nanowire, and thus our system provides a signature of the MBSs without direct electron transport through it.…”

d + id and d wave topological superconductors and new mechanisms for bulk boundary correspondence

“…13 Some other recent researches concerning topological superconductor include. 14,15 But, so far, it has been largely overlooked for the 2D TR breaking C 2 = −1 (class C in the Altland-Zirnbauer(AZ) classification 16,17 ) topological superconductors and for the 3D TR invariant class CI topological superconductors with T 2 = 1 and C 2 = −1. A few previous researches, by constructing theoretical models for simplest cases, include.…”