Figure 2: Typical operation of the single-atom electron pump.
(a) Time dependence of voltages VLG and VRG during the cycle. (b) The relevant tunnel rates from the source (solid lines) and to the drain (dashed line) during the pumping cycle for the 1s(A1) state (blue), the 1s(T2) state (purple) and the 1s(E) state (green). When a state is below the Fermi level of the source, the line is colored red. A grey line shows the relaxation rates for the 1s(T2) and 1s(E) states to the 1s(A1) state and a black dashed-dotted line shows the pumping frequency. (c) The corresponding occupation probabilities for the relevant single electron states of the atom as a function of time, where five moments in the cycle are highlighted with t1 to t5, as discussed in the text. (d) Number of pumped electrons (〈n〉 in Equation 5) as a function of the DC voltages VLG and VRG, using an AC sinusoidal driving voltage on VLG with a 300 mV amplitude and a 500 MHz frequency in the calculations. The red square corresponds to the pumping cycle as shown in (a),(b) and (c). The solid, dashed and dotted lines indicate the boundaries of the pumping plateau, as discussed in the text.
