Multiplexed Charge-locking Device for Large Arrays of Quantum Devices

TL;DR

This paper introduces a multiplexed charge-locking system for large quantum device arrays, enabling control beyond the limitations of available wiring in cryogenic systems, demonstrated through GaAs/AlGaAs quantum dots.

Contribution

It presents a novel multiplexed charge-locking architecture and a split-gate multiplexer design that allows control of large quantum arrays with fewer electrical contacts.

Findings

Successful fabrication on GaAs/AlGaAs substrates.

Charge locking stability with drift of about one Coulomb oscillation per hour.

Proof-of-concept demonstrated via Coulomb blockade measurements.

Abstract

We present a method of forming and controlling large arrays of gate-defined quantum devices. The method uses a novel, on-chip, multiplexed charge-locking system and helps to overcome the restraints imposed by the number of wires available in cryostat measurement systems. Two device innovations are introduced. Firstly, a multiplexer design which utilises split gates to allow the multiplexer to divide three or more ways at each branch. Secondly we describe a device architecture that utilises a multiplexer-type scheme to lock charge onto gate electrodes. The design allows access to and control of gates whose total number exceeds that of the available electrical contacts and enables the formation, modulation and measurement of large arrays of quantum devices. We fabricate devices utilising these innovations on n-type GaAs/AlGaAs substrates and investigate the stability of the charge locked on to the gates. Proof-of-concept is shown by measurement of the Coulomb blockade peaks of a single quantum dot formed by a floating gate in the device. The floating gate is seen to drift by approximately one Coulomb oscillation per hour.