Gigahertz quantized charge pumping in graphene quantum dots

Abstract

Single-electron pumps are set to revolutionize electrical metrology by enabling the ampere to be redefined 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 megahertz pumping speeds that correspond to small currents of the order of picoamperes. Tunable barrier pumps in semiconductor structures are operated at gigahertz 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 that performs at frequencies up to several gigahertz. Combined with the record-high accuracy of the quantum Hall effect and proximity-induced Josephson junctions, 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, single Dirac fermion emission in relativistic electron quantum optics and read-out of spin-based graphene qubits in quantum information processing.

Resonant second-harmonic generation in a ballistic graphene transistor with an ac-driven gate

“…Several works in this direction show indeed that ac transport in graphene is a rich subject. Studies include quantum pumping [8][9][10][11][12], nonlinear electromagnetic response [13][14][15][16][17][18], and photon-assisted tunneling phenomena [19][20][21][22][23][24][25]. In theoretical investigations for low doping (Fermi energy E F close to the Dirac point) and high frequencies , with E F and of comparable magnitude (we put = 1), a true quantum mechanical description becomes necessary.…”

Energy and power fluctuations in ac-driven coherent conductors

“…Indeed, even the controlled emission of single electrons (or a fixed integer number of electrons) in a given time interval has been realized with periodically and nonlinearly driven mesoscopic capacitors [1][2][3] and electron pumps [4][5][6][7][8][9]. These setups are usually based on the emission of particles from a confined region such as a quantum dot.…”

Single-electron transport in graphene-like nanostructures

“…Over the past decade, GQDs have proven to be a useful platform for confining and manipulating single electrons [2,3,60,[84][85][86][87][88]. In this section, we will review a few relevant transport experiments performed on graphene single quantum dots (GSQDs) fabricated on SiO 2 /Si substrates.…”