Major experimental progress has focused on two material families that most closely approach conditions predicted to host Majorana zero modes: proximitized semiconductor nanowires and magnetic atom chains on superconductors. Evidence comes from multiple respected groups, but definitive, universally accepted proof is still debated.
Experimental platforms
Semiconductor nanowires made of indium antimonide InSb or indium arsenide InAs coated with a thin superconducting layer of aluminum Al have produced the clearest, reproducible signatures. V. Mourik and colleagues in the Kouwenhoven group at Delft University of Technology reported zero-bias conductance peaks consistent with theory for Majorana bound states in hybrid InSb-Al devices. Subsequent refinements including epitaxial Al on InAs and Coulomb-blockade experiments by S. M. Albrecht and Leo Kouwenhoven at Delft University of Technology and collaborators strengthened the case by demonstrating hard induced superconducting gaps and length-dependent suppression of mode splitting. These platforms realize the required ingredients: strong spin-orbit coupling, induced s-wave superconductivity, and a magnetic field that drives a topological transition.
A second route uses chains of magnetic atoms on the surface of a conventional superconductor. S. Nadj-Perge and Ali Yazdani at Harvard University observed localized zero-bias peaks at the ends of iron atom chains on lead Pb surfaces using scanning tunneling microscopy. That geometry exploits exchange-induced effective p-wave pairing and has the advantage of atomic-scale control of geometry and strong superconductivity from the host.
Evidence, causes, and consequences
The physical causes behind reported signatures are well founded in theory: when a one-dimensional system with strong spin-orbit coupling is proximized by a superconductor and tuned with a magnetic field, theory predicts the emergence of topologically protected end modes that are Majorana zero modes. Experimental consequences include zero-bias conductance peaks and spatially localized bound states. Reported observations from Delft University of Technology and Harvard University provide convergent but not unambiguous evidence because other phenomena such as disorder, Kondo resonances, or trivial Andreev bound states can produce similar spectroscopic features.
The stakes extend beyond fundamental physics to technology and regional research ecosystems. Confirmation would advance topological quantum computing, motivating investment by academic centers and industry hubs in the Netherlands, the United States, and elsewhere. Culturally, collaborative verification across institutions and techniques remains crucial to move from intriguing signatures to robust control of Majorana modes, with environmental and materials-availability factors influencing which platforms scale toward devices. Careful cross-confirmation and refined materials engineering remain essential before Majorana-based applications can be realized.