Few electron double quantum dot in an isotopically purified $^{28}$Si quantum well

TL;DR

This paper reports the creation of a few-electron double quantum dot in an isotopically purified $^{28}$Si quantum well with record-high electron mobility, minimal nuclear spin interactions, and reduced charge noise, advancing quantum computing prospects.

Contribution

The study demonstrates a high-mobility, low-nuclear-spin double quantum dot in $^{28}$Si with suppressed charge noise, highlighting improvements over previous silicon quantum dot devices.

Findings

Achieved electron mobility of 5.5 x 10^4 cm^2(Vs)^{-1} in $^{28}$Si QW.

Residual $^{29}$Si concentration below 10^3 ppm, reducing hyperfine interactions.

Complete suppression of hysteretic gate behavior and charge noise with a global top gate.

Abstract

We present a few electron double quantum dot (QD) device defined in an isotopically purified $^{28}$Si quantum well (QW). An electron mobility of $5.5 \cdot 10^4 cm^2(Vs)^{-1}$ is observed in the QW which is the highest mobility ever reported for a 2D electron system in $^{28}$Si. The residual concentration of $^{29}$Si nuclei in the $^{28}$Si QW is lower than $10^{3} ppm$, at the verge where the hyperfine interaction is theoretically no longer expected to dominantly limit the $T_{2}$ spin dephasing time. We also demonstrate a complete suppression of hysteretic gate behavior and charge noise using a negatively biased global top gate.