Shaping electron wave functions in a carbon nanotube with a parallel magnetic field

TL;DR

This study demonstrates that a magnetic field along a carbon nanotube's axis can modify the longitudinal electron wave functions, enabling control over their shape and conductance, due to the nanotube's unique topology and lattice structure.

Contribution

It reveals that axial magnetic fields influence longitudinal electron wave functions in carbon nanotubes, a novel effect due to their topology and lattice structure.

Findings

Wave functions can be tuned from half-wave to quarter-wave resonator shapes.

Conductance depends distinctly on the magnetic field.

Magnetic control of wave functions is possible in nanotubes with nontrivial topology.

Abstract

A magnetic field, through its vector potential, usually causes measurable changes in the electron wave function only in the direction transverse to the field. Here we demonstrate experimentally and theoretically that in carbon nanotube quantum dots, combining cylindrical topology and bipartite hexagonal lattice, a magnetic field along the nanotube axis impacts also the longitudinal profile of the electronic states. With the high (up to 17T) magnetic fields in our experiment the wave functions can be tuned all the way from "half-wave resonator" shape, with nodes at both ends, to "quarter-wave resonator" shape, with an antinode at one end. This in turn causes a distinct dependence of the conductance on the magnetic field. Our results demonstrate a new strategy for the control of wave functions using magnetic fields in quantum systems with nontrivial lattice and topology.