Upper frequency limit depending on potential shape in a QD-based single electron pump

Abstract

Our quantum-dot (QD) electron pump has uniqueness in design in that the QD potential shape can be manipulated, especially its potential depth can be controlled by a plunger gate. We find that there exist strong correlations between the potential depth of the QD and the upper frequency limit, fm, when the modulating microwave power is fixed. As the depth of the QD potential is deepened, fm shows decreasing characteristics while the flatness of the 1st current plateau is increased. We have semi-quantitatively analyzed these correlations by using the notion of so-called “non-adiabatic Coulomb blockade gap energy,” ΔELU. We find that ΔELU parameter being under control by a plunger gate is proportional to the pumping frequency f.

rf-Signal-induced heating effects in single-electron pumps composed of gate-tunable quantum dots

“…The result Z 0 = 100 is consistent with our previous estimation in Ref. [23]. The result α = 0.029 is also consistent with values observed for various gates and devices (refer to Fig.…”

Single‐Electron Pumps and Quantum Current Metrology in the Revised SI

“…Regarding the differences of GaAs‐ and Si‐based SEPs, there are indications that for pumping frequencies f SEP beyond 1 GHz (corresponding to about 160 pA) the accuracy of the generated currents in GaAs devices degrades drastically, while for devices fabricated in Si technology such frequency limit is less pronounced, or, respectively, shifted to higher f SEP . The possible physical reasons for such frequency limitation in GaAs‐based SEPs are not completely clear yet, but under investigation …”

Optimization of quantized charge pumping using full counting statistics

“…We can now analyze a charge pump which is similar to those from recent experiments. 2,7,[10][11][12][13]15,[17][18][19][20][22][23][24][25] The pump consists of a metallic island operated in the Coulomb-blockade regime, where the island is either empty or occupied by one electron. The rate matrix then takes the simple form…”

“…Moreover, pumps operating with a single modulated gate voltage only deliver a quantized current well beyond the adiabatic regime. [15][16][17][18][19][20][21][22][23][24][25] Various techniques have been developed to improve the accuracy of such non-adiabatic pumps at the quantized-current plateau. 36,37 On the other hand, efficient tools to optimize the driving frequency are still lacking, as it is challenging to develop theories that extend beyond the adiabatic approximation.…”