Peking University, March 19, 2025: A research team led by Professor Sun Qing-Feng in colloboration with Professor He Lin’s research group from Beijing Normal University has achieved orbital hybridization in graphene-based artificial atoms for the first time. Their findings, entitled “Orbital hybridization in graphene-based artificial atoms” was published in Nature (DOI: 10.1038/s41586-025-08620-z). This work marks a significant milestone in the field of quantum physics and materials science, bridging the gap between artificial and real atomic behaviors.

Why it matters:

1. Quantum dots, often called artificial atoms, can mimic atomic orbitals but have not yet been used to simulate orbital hybridization, a crucial process in real atoms. 

2. While quantum dots have successfully demonstrated artificial bonding and antibonding states, their ability to replicate orbital hybridization remained unexplored. 

3. A fundamental understanding of how anisotropic confinement affects hybridization in quantum dots was lacking.

Fig. 1. Upper panels: The schematic plots of (a) unhybridized orbitals and (b) sp2 orbital hybridization in real atoms. Lower panels: The schematic plots of (c) circular potential and (d) elliptical potential in graphene-based artificial atoms.

The Research:

The authors developed a theoretical framework and experimental approach to achieve orbital hybridization in graphene-based quantum dots.

1. They proposed that anisotropic potentials in artificial atoms could induce hybridization between confined states of different orbitals, such as the s orbital (orbital quantum number 0) and the d orbital (orbital quantum number 2).

2. By deforming the circular potential of graphene quantum dots into an elliptical potential, the team successfully induced orbital hybridization, resulting in two hybridized states with distinct shapes (θ shape and rotated θ shape).

3. The experimental results, obtained by probing confined states in various quantum dots, confirmed the theoretical predictions, demonstrating the recombination of atomic collapse states (a quantum electrodynamics phenomenon) and whispering gallery modes (an acoustic phenomenon).

Fig. 2. (a, b) Numerically calculated hybridized states (θ shape and rotated θ shape). (c, d) Experimentally observed hybridized states. (e) Hybridized states split in energy versus the deformation of quantum dot.

Key Findings:

1. Orbital hybridization in artificial atoms was achieved for the first time, with hybridized states showing energy splitting as anisotropy increased.

2. This breakthrough provides a new platform for simulating real atomic processes, with potential applications in quantum computing and nanoelectronic

*This article is featured in PKU News' "Why It Matters" series. More from this series.

Click "here” to read the  paper

Written by: Akaash Babar
Edited by: Zhang Jiang
Source: School of Physics, Peking University