Manipulating quinary charge states in solitary defects of 2D intermetallic semiconductor

Creating and manipulating multiple charge states of a single atomic defect in semiconductors is of essential importance to "qubits" of solid-state quantum computation, but fundamentally limited by Coulomb's law. The object is challenged by the conflicting requirements of localization for sizable band gap and delocalization for low charging energy. Recently, researchers from China and Singapore realized exotic quinary charge states of single defect in two-dimensional intermetallic semiconductor Sn2Bi, and observed an ultralow defect charging energy.