A group of researchers at Delft University have made impressive progress in realizing and studying Majorana bound states. Their creation of a new quantum-dot based system would provide researchers new ways to accurately control and manipulate these tricky particles. This important work will advance the frontiers of topological quantum computing. The race to build a quantum computer takes advantage of the special nature of Majoranas to engineer robust quantum bits.
Majoranas are expected to be realizable in one-dimensional chains of artificial atoms called quantum dots (QDs). The Delft researchers created their system “block-by-block.” They started with the minimal Kitaev model, which laid the groundwork for predicting Majoranas all the way back in 2000. Once made, Srijit Goswami’s team wanted to test these theoretical predictions with practical experimentation, yielding invaluable insights into Majorana-based quantum bits.
One feature crucial to the stability of topological qubits is the existence of a “bulk-gap.” This gap in effect distinguishes two Majorana bound states. While earlier works have shown Majoranas in long one-dimensional extended semiconductor-superconductor hybrid devices, many problems have persisted. Great disorder within these systems typically makes it very challenging to consistently control and characterize Majorana bound states with precision.
The Delft team had a very impressive achievement just recently. In their experiments, they were able to create an experimental chain of three coupled quantum dots all embedded in a 2DEG. This novel arrangement makes possible a reproducible method for the creation, manipulation, and probing of Majoranas in a systematic fashion. Second, the researchers found out how to transfer Majoranas from one quantum dot to another. This breakthrough is a key development in moving topological quantum computing closer to realization.
In addition, the team configured a T-shaped structure made up of six quantum dots. This architecture will allow operations braiding to be tested, a key operation in the formation of topological basic qubits. The research emphasized the fluctuation of conductance in the central quantum dot. This finding opens up the possibility of introducing or removing the bulk gap in their setup.
The Delft team’s results are encouraging and point to an interesting research direction going forward. They’re hoping to lengthen their chain of quantum dots even more, to make the process of swapping positions between two Majoranas possible. This advancement could lead to a more comprehensive understanding of how these particles can be utilized in practical applications for quantum computing.