Fig. 2
From: Coherent population trapping by dark state formation in a carbon nanotube quantum dot
Experimental signatures of coherent population trapping. a Experimental differential conductance as a function of back-gate voltage Vg and bias voltage Vb. Twelve consecutive Coulomb diamonds can be assigned to three carbon nanotube shells which get progressively occupied with N = 1 to N = 4 electrons. Current suppression (negative differential conductance) and faint Coulomb diamond borders are observed, indicated by blue and red arrows, respectively. b Current vs. gate voltage for the two values Vb = ±3.045 mV of the bias voltages corresponding to the green/purple lines in panel (a). Solid lines provide here a guide to the eye. Current suppression associated to coherent population trapping is indicated by red arrows. c Numerically evaluated stationary current qualitatively reproducing the experiment. The parameters used in the simulation are shown in Table 1
