Quantum correlations in chiral graphene nanoribbons

Area of Science:

• Condensed Matter Physics
• Quantum Information Science
• Materials Science

Background:

• Chiral graphene nanoribbons (CGNRs) exhibit unique electronic properties due to their edge states.
• Understanding quantum correlations like entanglement and quantum discord is crucial for developing quantum technologies.
• Thermal effects and electron interactions significantly influence quantum properties in nanostructures.

Purpose of the Study:

• To compute and analyze the entanglement and quantum discord (QD) between edge spins in CGNRs.
• To investigate the influence of temperature, ribbon width, and Coulomb repulsion on these quantum correlations.
• To assess the potential of CGNRs for applications in spin-quantum devices.

Main Methods:

• Utilized canonical ensemble calculations to model CGNRs thermalized with a reservoir at temperature T.
• Computed entanglement and quantum discord for various pairs of edge spins.
• Analyzed the dependence of quantum correlations on CGNR width and electron Coulomb repulsion.

Main Results:

• Entanglement is exclusively found between spins on opposite edges of the nanoribbon; no entanglement exists between spins on the same edge.
• Quantum discord (QD) is present in almost all edge spin pairs and is sensitive to ribbon width and Coulomb repulsion.
• The strongest entanglement occurs between nearest-neighbor spins across the ribbon, showing remarkable robustness even at room temperature, particularly in narrow CGNRs with weak Coulomb repulsion.

Conclusions:

• CGNRs exhibit distinct patterns of entanglement and quantum discord in their edge spins.
• The robustness of inter-edge spin entanglement at room temperature highlights CGNRs as promising candidates for practical spin-quantum devices.
• Tailoring CGNR properties, such as width and Coulomb interaction, can optimize their quantum correlation characteristics for device applications.