  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.
