  We report on the transport study of a double quantum dot (DQD) device made
from a freestanding, single crystalline InSb nanosheet. The freestanding
nanosheet is grown by molecular beam epitaxy and the DQD is defined by top gate
technique. Through the transport measurements, we demonstrate how a single
quantum dot (QD) and a DQD can be defined in an InSb nanosheet by tuning
voltages applied to the top gates. We also measure the charge stability
diagrams of the DQD and show that the charge states and the inter-dot coupling
between the two individual QDs in the DQD can be efficiently regulated by the
top gates. Numerical simulations for the potential profile and charge density
distribution in the DQD have been performed and the results support the
experimental findings and provide a better understanding of fabrication and
transport characteristics of the DQD in the InSb nanosheet. The achieved DQD in
the two-dimensional InSb nanosheet possesses pronounced benefits in lateral
scaling and can thus serve as a new building block for developments of quantum
computation and quantum simulation technologies.
