Fig. 1
From: Coherent population trapping by dark state formation in a carbon nanotube quantum dot
All-electronic dark states in a carbon nanotube quantum dot. a Quantum dot setup to probe coherent population trapping in a dark state (DS). For the chosen bias voltage polarity, an electron can enter a DS from the left lead but it cannot leave it by tunneling to the right lead. Precession allows population transfer from the dark state to the coupled state (CS). b A CNT features degenerate angular momentum states. Linear combinations of angular momentum states for single-electron occupancy (N = 1) of a given nanotube shell can give rise to CS and DS. The latter is represented by the eight-shaped orbital in panel (c). c Effective Lambda-system for coherent population trapping in a CNT quantum dot. Because an electron in the DS cannot leave the carbon nanotube, the state N = 0, corresponding to an empty shell configuration, can no longer be reached. CNT carbon nanotube
