``X-Ray Edge'' Singularities in Nanotubes and Quantum Wires with Multiple Subbands

TL;DR

This paper investigates the impact of electron interactions on the tunneling density of states in nanotubes and quantum wires, revealing a suppressed singularity due to many-body effects while maintaining quasiparticle integrity.

Contribution

It demonstrates how interactions modify the van Hove singularity in one-dimensional systems, introducing a power-law suppression similar to the x-ray edge effect.

Findings

Interaction causes a power B ≈ 0.3 suppression of the singularity.

Quasiparticles remain well-defined despite the anomalous tunneling behavior.

The study extends understanding of many-body effects in nanotubes and quantum wires.

Abstract

Band theory predicts an inverse square root van Hove singularity in the tunneling density of states at the minimum energy of an unoccupied subband in a one-dimensional quantum wire. With interactions, an orthogonality catastrophe analogous to the x-ray edge effect for core levels in a metal strongly reduces this singularity by a power B of the energy above threshold, with B approximately 0.3 for typical carbon nanotubes. Despite the anomalous tunneling characteristic, good quasiparticles corresponding to the unoccupied subband states do exist.