Tunable Valley Splitting and Bipolar Operation in Graphene Quantum Dots

Quantum states in graphene are four-fold degenerate: two fold spins, and valleys.Both degrees of freedom can be utilized for qubit preparations. In our bilayer quantumdots, we demonstrate that the valley g-factorgv, defined analogously as spin g-factorgsforvalley splitting perpendicular magnetic field, is tunable by over a factor 4 from 20 to 90. Wefind largergvresults larger electronic dot sizes, determined charging energy.This control achieved adjusting voltages on merely gates, which also allows tuning ofthe dot-lead tunnel coupling. On versatile device, bipolar operation, quantum dotwith charge carriers same or opposite polarity leads, performed. Dots ofboth first carrier action plunger gate, such thetransition an electron hole observed. By adding more this system caneasily extended host double dots.