Molecular Collapse States in Elliptical Graphene/WSe2 Heterostructure Quantum Dots

TL;DR

This paper investigates atomic collapse states in elliptical graphene quantum dots, demonstrating how Klein tunneling influences these states and revealing their fundamental connection through combined experimental and theoretical analysis.

Contribution

It provides the first systematic study linking atomic collapse states with Klein tunneling in elliptical graphene quantum dots, supported by experimental observations and theoretical calculations.

Findings

Observation of bonding and antibonding molecular collapse states.

Antibonding ACS transitions into Klein-tunneling-induced quasibound states.

Experimental and theoretical confirmation of the ACS-Klein tunneling connection.

Abstract

In relativistic physics, both atomic collapse in heavy nucleus and Hawking radiation in black hole are predicted to occur through Klein tunneling process that couples particles and antiparticles. Recently, atomic collapse states (ACSs) were explicitly realized in graphene because of its relativistic Dirac excitation with large fine structure constant. However, essential role of the Klein tunneling on the ACSs remains elusive in experiment. Here we systematically study the quasibound states in elliptical graphene quantum dots (GQDs). Bonding and antibonding molecular collapse states formed by two coupled ACSs are observed in the elliptical GQDs. Our experiments, supported by theoretical calculations, indicate that the antibonding state of the ACSs will change into a Klein-tunneling-induced quasibound state, revealing deep connection between the ACSs and the Klein tunneling.