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MagTop researchers propose a cavity-based diagnostic that uses quantum interference to tell true Majorana states apart from trivial excitations.
Distinguishing true (or useful) Majorana bound states (MBSs) from look-alike zero-energy modes remains one of the central challenges in topological superconductivity. A new theoretical study proposes a microwave-based method that could provide a robust way to tell genuine Majorana states apart from accidental excitations.
Majorana bound states are exotic quasiparticles predicted to emerge at the ends of topological superconductors and are promising candidates for fault-tolerant quantum computing because of their nonlocal nature. Yet identifying clear experimental signatures has proven difficult, as conventional zero-energy states — such as Andreev bound states or quasi-Majoranas — can mimic their transport signals. Standard conductance measurements alone, therefore, cannot always distinguish topological states from accidental subgap modes.
In a paper published in Physical Review B as an Editors’ Suggestion, Mr. Sarath Prem and Dr. Mircea Trif from the International Research Centre MagTop at IFPAN, together with collaborators from École Polytechnique (France), introduce a microwave cavity–based probe to distinguish genuine Majorana states from these look-alike modes.
The team studies a hybrid nanowire coupled to a microwave cavity and proposes the „visibility” of microwave absorption as a probe of fermion parity and nonlocality. Similar to visibility in optics — where interference determines the contrast of fringes — the effect here arises from interference between quantum transitions associated with different parity states, providing a direct window into the system’s nonlocal character. Genuine Majorana states produce a nonzero visibility only when both ends of the nanowire couple simultaneously to the cavity, reflecting their spatial separation, whereas trivial modes generate strong signals even for local coupling. This distinction remains robust under realistic conditions, including disorder and tunnel barriers, and also applies to minimal „poor man’s” Majorana systems.
By leveraging concepts from cavity quantum electrodynamics, the study introduces a non-transport probe for topological superconductivity that could complement conventional transport measurements in current hybrid platforms. The microwave-based approach provides an additional handle on fermion parity and nonlocality, highlighting MagTop’s contributions to advancing theoretical tools for topological quantum devices.
S. Prem, O. Dmytruk, M. Trif, Distinguishing Majorana bound states from accidental zero-energy modes with a microwave cavity, Phys. Rev. B 113, 085420 (2026) (Editors’ Suggestion), arXiv:2509.13194 (2025)