Semiconductor membranes for electrostatic exciton trapping in optically addressable quantum transport devices

TL;DR

This paper introduces a technique to create exciton traps in GaAs quantum wells using local electric fields in a thin heterostructure membrane, enabling advanced quantum devices with preserved high mobility.

Contribution

A novel top-down fabrication method for exciton trapping in quantum wells via membrane thinning and local electric fields, maintaining high mobility and device functionality.

Findings

High mobility (>1x10^6 cm^2V^-1s^-1) retained in thinned heterostructures

Observation of quantum point contacts and Coulomb oscillations

Confirmation of exciton energy modulation via quantum-confined Stark effect

Abstract

Combining the capabilities of gate defined quantum transport devices in GaAs-based heterostructures and of optically addressed self-assembled quantum dots could open broad perspectives for new devices and functionalities. For example, interfacing stationary solid-state qubits with photonic quantum states would open a new pathway towards the realization of a quantum network with extended quantum processing capacity in each node. While gated devices allow very flexible confinement of electrons or holes, the confinement of excitons without some element of self-assembly is much harder. To address this limitation, we introduce a technique to realize exciton traps in quantum wells via local electric fields by thinning a heterostructure down to a 220 nm thick membrane. We show that mobilities over $1 \times 10^{6}$ cm$^{2}$V$^{-1}$s$^{-1}$ can be retained and that quantum point contacts and Coulomb oscillations can be observed on this structure, which implies that the thinning does not compromise the heterostructure quality. Furthermore, the local lowering of the exciton energy via the quantum-confined Stark effect is confirmed, thus forming exciton traps. These results lay the technological foundations for devices like single photon sources, spin photon interfaces and eventually quantum network nodes in GaAs quantum wells, realized entirely with a top-down fabrication process.