Leakage of Majorana mode into correlated quantum dot nearby its singlet-doublet crossover

Abstract

We study quasiparticle spectrum of the correlated quantum dot deposited on superconducting substrate which is side-coupled to the Rashba nanochain, hosting Majorana end modes. Ground state of an isolated quantum dot proximitized to superconducting reservoirs is represented either by the singly occupied site or BCS-type superposition of the empty and doubly occupied configurations. Quantum phase transition between these distinct ground states is spectroscopically manifested by the in-gap Andreev states which cross each other at the Fermi level. This qualitatively affects leakage of the Majorana mode from the side-attached nanowire. We inspect the spin-selective relationship between the trivial Andreev states and the leaking Majorana mode, considering (i) perfectly polarized case, when tunneling of one spin component is completely prohibited, and (ii) another one when both spins are hybridized with the nanowire but with different couplings. *

Topological isoconductance signatures in Majorana nanowires

“…It is worth mentioning that Eq. ( 7 ) has the shape similar to those derived by Zienkiewicz et al 61 , Górski and Kucab 77 (without the S reservoir) and Ramos–Andrade et al 93 (for a QD between N leads and side coupled to two TSC nanowires). However, in none of these references finite , necessary for the estimation of the degree of Majorana nonlocality, was introduced.…”

“…One can clearly notice the presence of the pronounced four peak structure around corresponding to the well resolved Andreev levels, appearing due to the QD-TSC coupling and splitted by the external magnetic field. Moreover, there is a visible zero-bias structure present because of the leakage of an isolated MBSs into the QD 18 , 58 , 61 , 65 , whose amplitude changes with , and reaches the maximal value of for .…”

“…In the current work, by analyzing the Andreev current through a quantum dot (QD) placed between metallic (N) and superconducting (S) reservoirs and coupled to a TSC hosting MBSs (Majorana nanowire), see Fig. 1 a 58 – 61 , we theoretically propose an additional protocol to differentiate between the corresponding foregoing cases of: Highly nonlocal and nonoverlapping MBSs: corresponds to the case of long nanowires, , wherein L is the TSC section length and is the Majorana coherence length 28 . In such a situation, the wave functions of the MBSs are well localized at the TSC nanowire ends, leading to both a zero overlap between them and a zero coupling of QD state with the faraway (right) MBS.…”

Majorana Bound State leakage to impurity in Su-Schrieffer-Heeger-Rashba scenario

“…Theoretical study of this behavior showed, that the interplay between trivial ABS and topological MBS strongly depends by spin polarization of the ABS [27,55,60,61], due to positive spin polarization of the MBS [28]. In such case, the avoided crossing or resonance of the ABS energy levels can be observed [62][63][64]. Moreover, this behavior can be helpful in distinguishing MBS from ABS [65,66].…”

Majorana mode leaking into a spin-charge entangled double quantum dot

“…Another important aspect making such hybrid systems interesting is related to the impact and signatures of the presence of Majorana modes in the transport properties of attached low-dimensional structures [13,[23][24][25][26][27][28][29][30][31][32][33][34]. In this regard, the leakage of Majorana zero-energy modes into attached quantum dots has been a subject of extensive investigations [35][36][37][38]. It was shown that the coupling to topological superconductor hosting Majorana quasiparticles (Majorana wire) results in fractional values of the conductance [35,39].…”