Cooper pair splitting in a two-dimensional electron gas I: Probing virtual processes

Cooper pair splitting (CPS) has been studied extensively in semiconductor-superconductor hybrids. However, it has thus far been challenging to isolate CPS from other local and non-local processes, such as local Andreev reflection and elastic co-tunnelling (ECT). Recent studies in hybrid nanowires [1] demonstrate that these challenges can be overcome to achieve highly efficient Cooper pair splitting.  Here we present the first demonstration of CPS in a semiconductor two-dimensional electron gas. By coupling two quantum dots to the hybrid section via extended Andreev bound states, and operating the dots as charge filters,  we achieve a CPS efficiency up to 95% , on par with the highest reported values. Using the two spin-degenerate, single-orbital dot levels, we observe specific spin blockades that are strongly dependent on the applied bias polarities and the nature of the underlying non-local virtual processes.

 

[1] Wang, G., et al., arXiv:2205.03458 (2022)