Quantum dots with triplet and noncentrosymmetric superconducting leads

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Two fields of current interest in condensed matter physics are combined in this theoretical project. One of them concerns unconventional superconductors, in particular so-called triplet and noncentrosymmetric superconductors which have complex magnetic properties. They possess unusual surface states, i.e., states in which electrons can only move along the surface, not into the bulk. For example, there can be a large number of such surface states with vanishing energy, suggested to form a solid-state realization of so-called Majorana fermions. These are particles that form their own antiparticles. The other relevant field is electronic transport through nanometer-size molecules or artificial structures. Here, quantum-mechanical effects lead to behaviors quite distinct from transport at larger scales. This field is also crucial for technological progress in electronics. The objective of the present project is to theoretically study transport through such nanostructures between electrodes made from triplet or noncentrosymmetric superconductors. It is expected that the interplay between the physics of unconventional superconductors on the one hand and quantum effects in transport through nanostructures on the other will lead to novel physics. For example, if many Majorana states are present in the superconducting leads, they will dramatically change the current-voltage characteristics. The goals of this project are to find and to understand such new effects. Complementary theoretical methods appropriate for weak and strong coupling between the nanostructure and the leads will be used to achieve these goals.