Towards Fast Readout and Control of Single-electron Pumps Based on CVD Graphene

The two-dimensional character of graphene makes it a promising material for realizing high-accuracy single-electron pumps for applications in quantum metrology^[1]. Double quantum dots etched from exfoliated flakes, however, lack the scalability and reproducibility required for high-current generation and their ultimate accuracy remains to be seen. We present a fabrication process and low-temperature radiofrequency reflectometry setup for detecting error rates in scalable DQDs based on CVD graphene. To improve device reproducibility we use atomic layer deposition of aluminium oxide with in situ gaseous water pretreatments to achieve negligible gate hysteresis, low doping levels, and lower disorder compared to as-fabricated flakes^[2]. Using radiofrequency reflectometry we probe single-electron tunnelling rates in DQDs with high sensitivity and at millikelvin temperatures. Using the same setup we also perform low temperature experiments and discuss the advantages of an alternative type of graphene single-electron device based on magnetically confined state in the quantum Hall regime^[3].

[1] M. R. Connolly et al., Nat. Nano. 8, 417–420 (2013)
[2] J. Alexander-Webber et al., 2D Mater. 4, 011008 (2016)
[3] M. Kataoka et al., Phys. Rev. Lett. 83, 160 (1999)