Molecular Collapse States in Graphene/WSe_{2} Heterostructure Quantum Dots

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Relativistic Physics

Background:

• Atomic collapse states (ACSs) and Klein tunneling are key phenomena in relativistic physics, observed in heavy nuclei and black holes.
• Graphene exhibits relativistic Dirac excitation, enabling the realization of ACSs due to its large "fine structure constant."
• The experimental role of Klein tunneling in graphene's ACSs has remained unclear.

Purpose of the Study:

• To systematically investigate quasibound states in elliptical graphene quantum dots (GQDs) and coupled circular GQDs.
• To elucidate the connection between ACSs and Klein tunneling in experimental systems.

Main Methods:

• Experimental study of quasibound states in engineered graphene quantum dot geometries (elliptical and coupled circular).
• Theoretical calculations to support experimental observations and interpret quantum phenomena.
• Analysis of bonding and antibonding molecular states formed by coupled ACSs.

Main Results:

• Observation of bonding and antibonding molecular collapse states in both elliptical and coupled circular GQDs.
• Experimental evidence indicates that the antibonding state of ACSs transforms into a Klein-tunneling-induced quasibound state.
• Demonstration of a deep connection between ACSs and Klein tunneling in graphene systems.

Conclusions:

• The study experimentally confirms the role of Klein tunneling in graphene's atomic collapse states.
• Findings reveal a fundamental link between ACSs in graphene and the relativistic Klein tunneling process.
• This research bridges concepts from condensed matter physics and relativistic quantum mechanics.