Effective tuning methods for few-electron regime in gate-defined quantum dots

TL;DR

This paper introduces systematic compensation techniques for gate crosstalk in gate-defined quantum dots, enabling precise control and observation of Coulomb blockade peaks from single-electron to about twenty electrons.

Contribution

It presents two novel approaches to mitigate gate crosstalk effects, improving control over quantum dot states across a wide electron number range.

Findings

Successfully observed Coulomb blockade peaks from N=1 to N≈20.

Demonstrated effective compensation of gate crosstalk effects.

Provided a simple method for maintaining quantum dot control.

Abstract

We present systematic methods for compensating gate crosstalk effects in gate-defined quantum dots (QDs), to allow the observation of Coulomb blockade peaks from the few-electron regime (N = 1) to N \approx 20. Gate crosstalk, where adjustments to one gate voltage unintentionally affect other gate-controlled parameters, makes it difficult to control tunneling rates and energy states of the QD separately. To overcome this crosstalk effect, we present two approaches: maintaining constant conductance of two quantum point contacts (QPCs) forming the QD by compensating the effect of the plunger gate voltage on the QPCs, and interpolating between gate voltage conditions optimized for QD observation at several electron numbers. These approaches minimize crosstalk effects by dynamically adjusting barrier gate voltages as a function of plunger gate voltage. Using these methods, we successfully observed Coulomb blockade peaks throughout the entire range from N = 1 to N \approx 20. Our methods provide a simple and effective solution for observing Coulomb blockade peaks over a wide range of electron numbers while maintaining control over the quantum states in the dot.