Single-electron occupation in quantum dot arrays at selectable plunger gate voltage

TL;DR

This paper demonstrates a method to stabilize single-electron charge states in quantum dot arrays by using stress voltages, simplifying gate voltage tuning and potentially improving scalability of quantum computing hardware.

Contribution

It introduces a stress voltage technique to equalize and set gate voltages for quantum dots, enabling stable charge states without device-specific tuning.

Findings

Achieved stable (1,1) charge state at identical gate voltages in double quantum dots.

Successfully extended the method to a 2x2 quadruple quantum dot array.

Potential to reduce control complexity in spin qubit quantum hardware.

Abstract

The small footprint of semiconductor qubits is favourable for scalable quantum computing. However, their size also makes them sensitive to their local environment and variations in gate structure. Currently, each device requires tailored gate voltages to confine a single charge per quantum dot, clearly challenging scalability. Here, we tune these gate voltages and equalize them solely through the temporary application of stress voltages. In a double quantum dot, we reach a stable (1,1) charge state at identical and predetermined plunger gate voltage and for various interdot couplings. Applying our findings, we tune a 2$\times$2 quadruple quantum dot such that the (1,1,1,1) charge state is reached when all plunger gates are set to 1 V. The ability to define required gate voltages may relax requirements on control electronics and operations for spin qubit devices, providing means to advance quantum hardware.