Andreev and Majorana bound states in single and double quantum dot structures

Area of Science:

• Condensed Matter Physics
• Quantum Computing
• Mesoscopic Physics

Background:

• Majorana bound states (MBS) and Andreev bound states (ABS) are crucial for topological quantum computing.
• Understanding their emergence and coexistence in hybrid systems is essential.

Purpose of the Study:

• Investigate the emergence and coexistence of MBS and ABS in a system of two coupled quantum dots.
• Explore the influence of interdot coupling and the topological phase of a superconductor on these states.

Main Methods:

• Numerical study employing a recursive Green's function technique.
• Analysis of the local density of states for the quantum dot system.

Main Results:

• MBS and ABS appear in distinct regimes and do not coexist in single quantum dots.
• In coupled double dots, ABS can be localized or extended depending on interdot coupling.
• In the topological phase, ABS localize to one dot while MBS appear on the other, or ABS extend across the molecule with MBS localized.

Conclusions:

• Coexistence of MBS and ABS is achievable in coupled quantum dot systems.
• The topological phase of the superconductor significantly influences the spatial distribution and coexistence of these bound states.