First-principles study of the optical and spin properties of sp3-doped (6,5) single-walled carbon nanotubes as a candidate for optically-addressable qubit
Embargo Date
2025-08-03
OA Version
Citation
Abstract
Single-walled carbon nanotubes (SWCNTs) are promising optoelectronic materials due to their low cost, flexibility, and dopant-tunable photoluminescence and electrical properties. Confined in 1D, electron-hole interactions in SWCNTs become more significant compared with traditional semiconductors, as evidenced by high exciton binding energies. Additionally, an exciton trapping potential may be introduced by the presence of sp3 defects in a tube, increasing exciton lifetime and photon luminescence conversion efficiency. These defects can introduce unpaired spins with strong spin-orbit coupling, leading to correlated spin and excitonic behaviors that are difficult to understand but important for understanding the role of this class of materials for many applications such as quantum communication. In this dissertation, we study the electronic and spin structure of doped (6,5) SWCNT within first-principles density functional theory and many-body perturbation theory, connecting our simulation to observed phenomena from experiments. For a series of unpassivated sp3 defects, we predict the formation of a singly-occupied mid-gap electronic state centered at the sp3 site, with little spin density on the aromatic rings of the defect. We propose a new synthetic route for creating a doped system with significant density on Pd, and therefor an increase in spin-orbit coupling and intersystem crossing. We then utilize a spin diffusion model to demonstrate the long spin lifetime of up to μs. Lastly, we demonstrate that low-energy excited-state associated with single-phonon emission consist of a mixture of defect-like and symmetry broken band-like transitions. Overall, we have demonstrated the potential of sp3-doped (6,5) SWCNT as a molecular-scale qubits with long coherence times for use in quantum sensing, information
Description
2023