Using “Noise” to Detect Majorana States

Majorana bound states (MBSs) could be the qubits of the future. These unique electronic states are expected to be resistant to environmental perturbations that destroy the information in currently known qubits. However, MBSs have one major drawback: researchers are not sure to have actually observed them. Candidate states located at the ends of semiconductor-superconductor nanowires bear some characteristic features of MBSs, but they might be impostors instead. A new method—proposed by Jan Manousakis from the University of Cologne in Germany and colleagues—could potentially offer a way to distinguish real from fake MBSs by measuring statistical correlations between currents flowing in connected nanowires [1]. The advantage of this technique is that the states could be tested without the complication of trying to move them. Moving MBSs around each other in a particular way would be the ultimate test of authenticity, but such experiments have proven very difficult to do.