Gigahertz quantized charge pumping in graphene quantum dots

TL;DR

This paper reports the development of a graphene-based single-electron pump operating at GHz frequencies, with low predicted error rates, advancing quantum metrology and potential quantum information applications.

Contribution

It introduces a monolithic, fixed barrier graphene electron pump capable of GHz operation with low error rates, a significant improvement over previous technologies.

Findings

Operates at frequencies up to 1.4 GHz

Predicted error rate as low as 0.01 ppm at 90 MHz

Enables potential closure of the quantum metrological triangle

Abstract

Single electron pumps are set to revolutionize electrical metrology by enabling the ampere to be re-defined in terms of the elementary charge of an electron. Pumps based on lithographically-fixed tunnel barriers in mesoscopic metallic systems and normal/superconducting hybrid turnstiles can reach very small error rates, but only at MHz pumping speeds corresponding to small currents of the order 1 pA. Tunable barrier pumps in semiconductor structures have been operated at GHz frequencies, but the theoretical treatment of the error rate is more complex and only approximate predictions are available. Here, we present a monolithic, fixed barrier single electron pump made entirely from graphene. We demonstrate pump operation at frequencies up to 1.4 GHz, and predict the error rate to be as low as 0.01 parts per million at 90 MHz. Combined with the record-high accuracy of the quantum Hall effect and proximity induced Josephson junctions, accurate quantized current generation brings an all-graphene closure of the quantum metrological triangle within reach. Envisaged applications for graphene charge pumps outside quantum metrology include single photon generation via electron-hole recombination in electrostatically doped bilayer graphene reservoirs, and for readout of spin-based graphene qubits in quantum information processing.