Transport through an impurity tunnel coupled to a Si/SiGe quantum dot

TL;DR

This paper demonstrates controllable tunnel coupling between a silicon quantum dot and a localized impurity state, advancing the development of hybrid donor and quantum dot qubits in silicon.

Contribution

It reports the first characterization of a quantum dot coupled to a localized impurity state with gate-voltage controllable tunnel coupling in silicon.

Findings

Evidence of controllable coupling between quantum dot and impurity.

Identification of the impurity location near the quantum well edge.

Transport measurements consistent with gate-tunable tunnel coupling.

Abstract

Achieving controllable coupling of dopants in silicon is crucial for operating donor-based qubit devices, but it is difficult because of the small size of donor-bound electron wavefunctions. Here we report the characterization of a quantum dot coupled to a localized electronic state, and we present evidence of controllable coupling between the quantum dot and the localized state. A set of measurements of transport through this device enable the determination of the most likely location of the localized state, consistent with an electronically active impurity in the quantum well near the edge of the quantum dot. The experiments we report are consistent with a gate-voltage controllable tunnel coupling, which is an important building block for hybrid donor and gate-defined quantum dot devices.