Majorana bound states in a disordered quantum dot chain

Abstract

We study Majorana bound states in a disordered chain of semiconductor quantum dots proximitycoupled to an s-wave superconductor. By calculating its topological quantum number, based on the scattering-matrix method and a tight-binding model, we can identify the topological property of such an inhomogeneous one-dimensional system. We study the robustness of Majorana bound states against disorder in both the spin-independent terms (including the chemical potential and the regular spin-conserving hopping) and the spin-dependent term, i.e., the spin-flip hopping due to the Rashba spin-orbit coupling. We find that the Majorana bound states are not completely immune to the spinindependent disorder, especially when the latter is strong. Meanwhile, the Majorana bound states are relatively robust against spin-dependent disorder, as long as the spin-flip hopping is of uniform sign (i.e., the varying spin-flip hopping term does not change its sign along the chain). Nevertheless, when the disorder induces sign-flip in spin-flip hopping, the topological-nontopological phase transition takes place in the low-chemical-potential region.

Wave scattering properties of multiple weakly coupled complex systems

“…It has proven possible to perform experiments for interacting systems and measure transmission as a function of coupling. Examples include measurements of conductance of quantum dots systems with coupled electron billiards [12][13][14], resistance of disordered nanowires modeled by a cascade of quantum dots [15][16][17][18], and simulating resonance strength of coupled quantum mechanical systems with superconducting MW billiards [19], etc. Likewise, the EM wave properties of inter-connected electrically large enclosures, like the power flow and the impedance or scattering parameters, are also widely studied in engineering [20,21] in situations ranging from computer enclosures to rooms or buildings [22][23][24][25].…”

Weyl points in systems of multiple semiconductor-superconductor quantum dots

“…[23][24][25] Another way to simulate the Kitaev chain is with chains of semiconductor-superconductor quantum dots. [26][27][28][29][30] For an infinite chain of quantum dots, the MZMs are sepa-rated in a continuous range of control parameters. However, for a chain of a finite number of dots, as in Fig.…”

Majorana bound state engineering via efficient real-space parameter optimization

“…In spite of the aforementioned advances, the current state of knowledge for the realization of MBS is restricted to a small region of parameter space, comprised mainly of translationally-invariant wires. Systems with nonuniform parameters, such as superconducting gaps, magnetic fields and electrostatic potential profiles, are not analytically tractable beyond a few limiting periodic cases [10][11][12][13][14][15][16][17], and the existing numerical studies [18][19][20][21][22] have not been exhaustive. Thus, it would be desirable to chart the vast space of tunable experimental parameters beyond the known subregions, not only to find out if inhomogeneities could be a resource for MBS experiments, but also to provide new insights for improving Majorana-based qubits [23][24][25].…”