Sagnac interference in Carbon nanotube loops

TL;DR

This paper investigates electron interference in carbon nanotube loops, revealing Sagnac-like oscillations in conductance due to velocity differences, with implications for quantum interference phenomena in nanoscale systems.

Contribution

It demonstrates the presence of Sagnac interference in nanotube loops and analyzes the effects of electron interactions on these oscillations.

Findings

Conductance oscillates with voltage due to electron interference.

Oscillation periods are larger than in Fabry-Perot interference.

Interactions modify but do not eliminate the interference effects.

Abstract

In this paper we study electron interference in nanotube loops. The conductance as a function of the applied voltage is shown to oscillate due to interference between electron beams traversing the loop in two opposite directions, with slightly different velocities. The period of these oscillations with respect to the gate voltage, as well as the temperatures required for the effect to appear, are shown to be much larger than those of the related Fabry-Perot interference. This effect is analogous to the Sagnac effect in light interferometers. We calculate the effect of interactions on the period of the oscillations, and show that even though interactions destroy much of the near-degeneracy of velocities in the symmetric spin channel, the slow interference effects survive.