Charge sensing and controllable tunnel coupling in a Si/SiGe double quantum dot

TL;DR

This paper demonstrates tunable charge sensing and controllable tunnel coupling in a Si/SiGe double quantum dot, advancing the control of spin qubits in silicon-based quantum computing devices.

Contribution

It introduces a method to tune and measure tunnel coupling in silicon quantum dots using integrated charge sensing, showing exponential dependence on gate voltage.

Findings

Tunnel coupling is tunable via gate voltage.

Charge sensing enables extraction of tunnel coupling.

Control of tunnel barrier is achieved with a single gate.

Abstract

We report integrated charge sensing measurements on a Si/SiGe double quantum dot. The quantum dot is shown to be tunable from a single, large dot to a well-isolated double dot. Charge sensing measurements enable the extraction of the tunnel coupling, t, between the quantum dots as a function of the voltage on the top gates defining the device. Control of the voltage on a single such gate tunes the barrier separating the two dots. The measured tunnel coupling is an exponential function of the gate voltage. The ability to control t is an important step towards controlling spin qubits in silicon quantum dots.