Lamb shift of the Dirac cone of graphene

TL;DR

This paper demonstrates that vacuum electromagnetic fluctuations induce a significant Lamb shift in graphene's Dirac cone, leading to measurable electronic level and velocity renormalizations, larger than in isolated atoms.

Contribution

First-principles calculation showing a sizable Lamb shift in graphene's Dirac cone due to vacuum fluctuations, a novel effect not previously quantified.

Findings

Lamb shift in graphene is approximately 4 meV.

Electronic velocities in graphene are renormalized by vacuum fluctuations.

The effect is an order of magnitude larger than in isolated carbon atoms.

Abstract

The fluctuations of the electromagnetic vacuum are one of the most powerful manifestations of the quantum structure of nature. Their effect on the Dirac electrons of graphene is known to induce some spectacular and purely quantistic phenomena, like the Casimir and the Aharanov--Bohm effects. In this work we demonstrate, by using a first principles approach, that the Dirac cone of graphene is also affected by a sizable Lamb shift.We show that the microscopic electronic currents flowing on the graphene plane couple efficiently with the vacuum fluctuations causing a renormalization of the electronic levels (as large as 4 meV) and of the velocities. This Lamb shift is one order of magnitude larger than the value predicted for an isolated carbon atom.