Imaging microscopic structure of a tunable quantum dot in bilayer graphene (Part I)

Semiconductor quantum dots are a promising platform for quantum information processing, sensing and many-body simulation. Conventionally, the dot's state is probed by global measurements such as conductivity or capacitance; consequently, the microscopic structure of multi-particle ground states in the interacting regime has so far eluded direct experimental observation. Here we present a new experimental architecture that combines the exceptional spatial resolution of scanning tunneling microscopy (STM) with full gate control of the charge state of a bilayer graphene quantum dot, enabling direct visualization of quantum-dot states while tuning dot filling and confining potential. In the first part of this series of presentations, I will introduce the experimental platform and spectroscopic imaging of the dot's orbital wavefunctions, from which we unambiguously determine the shell structure of the dot. These measurements establish the high tunability of our device and demonstrate our capability to resolve the dot's microscopic structure via local spectroscopy.