Quantized charge transport driven by a surface acoustic wave in induced unipolar and bipolar junctions

Abstract

Surface acoustic waves (SAWs) have been used to transport single electrons across long distances of several hundreds of microns. They can potentially be instrumental in the implementation of scalable quantum processors and quantum repeaters, by facilitating interaction between distant qubits. While most of the work thus far has focused on SAW devices in doped GaAs/AlGaAs heterostructures, we have developed a method of creating lateral p-n junctions in an undoped heterostructure containing a quantum well, with the expected advantages of having reduced charge noise and increased spin-coherence lifetimes due to the lack of dopant scattering centres. We present experimental observations of SAW-driven single-electron quantised current in an undoped GaAs/AlGaAs heterostructure, where single electrons were transported between regions of induced electrons. We also demonstrate pumping of electrons by a SAW across the sub-micron depleted channel between regions of electrons and holes, and observe light emission at such a lateral p-n junction. Improving the lateral confinement in the junction should make it possible to produce a quantised electron-to-hole current and hence SAW-driven emission of single photons.

High Frequency Sonoprocessing: A New Field of Cavitation‐Free Acoustic Materials Synthesis, Processing, and Manipulation

“…[231][232][233] Subsequently, the Rayleigh SAW, viewed as a moving electrical superlattice potential, was shown to modify the electronic dispersion of ballistic graphene close to the charge-neutrality point [234][235][236] with an acoustoelectric current that is dependent on the SAW propagation direction. [237][238][239] Similar acoustoelectric coupling has also been observed in graphene ranoribbons, [240,241] QDs, [242][243][244][245] suspended quantum point contacts, [246] GaAs [247] and GaAs/AlGaAs hetrostructures, [248,249] and, more recently, 2D materials such as MoS 2 [250] and black phosphorous, [251] in which an anomalous acoustoelectric current was sustained.…”

Numerical analysis of surface acoustic wave driven carriers transport in GaAs/AlGaAs quantum well

“…The long-range transport of the optical excitations was demonstrated in a device by Rudolph 16 . It is a promising method for achieving single photon sources and single photon detectors 17 – 22 This makes use of the fact that, in a semiconductor piezoelectric material, the electrons and holes are separated by surface acoustic waves (SAWs) that have periodical potential, as shown in Fig.…”

Effects of biased and unbiased illuminations on two-dimensional electron gases in dopant-free GaAs/AlGaAs

“…Such devices, with possible applications such as spin-to-photon [36] or photon-to-spin [37] conversions, often need to be periodically warmed up to room temperature to be "reset." This issue is also relevant for some proposed single photon source proposals [38,39] which would use so-called "lateral" dopant-free p-i-n junctions [40][41][42].…”