The ability to tune local parameters of quantum Hamiltonians has been demonstrated in experimental systems including ultracold atoms, trapped ions, superconducting circuits and photonic crystals. Such systems possess negligible disorder, enabling local tunability. Conversely, in condensed-matter systems, electrons are subject to disorder, which often destroys delicate correlated phases and precludes local tunability. The realization of a disorder-free and locally-tunable condensed-matter system thus remains an outstanding challenge. Here, we demonstrate a new technique for deterministic creation of locally-tunable, ultralow-disorder electron systems in carbon nanotubes suspended over complex electronic circuits. Using transport experiments we show that electrons can be localized at any position along the nanotube and that the confinement potential can be smoothly moved from location to location. The high mirror symmetry of transport characteristics about the nanotube centre establishes the negligible effects of electronic disorder, thus allowing experiments in precision-engineered one-dimensional potentials. We further demonstrate the ability to position multiple nanotubes at chosen separations, generalizing these devices to coupled one-dimensional systems. These capabilities could enable many novel experiments on electronics, mechanics and spins in one dimension.
Bibliographical noteFunding Information:
The authors thank N. Shadmi and E. Joselevich for nanotube growth in the initial stages of the project, D. Mahalu for electron-beam writing, A. Yoffe and S. Garusi for dry etching and F. Kuemmeth, P. McEuen, H. Shtrikman, F. von-Oppen and A. Yacoby for comments on the manuscript. S.I. acknowledges financial support from the ISF Legacy Heritage foundation (grant 2005/08-80.0), the Bi-National Science Foundation (BSF) (grant 710647-03), the Minerva Foundation (grant 780054), the ERC Starters (grant 258753), the Marie Curie People (grant 239322) (IRG) and the Alon Fellowship. S.I. is incumbent of the William Z. and Eda Bess Novick career development chair.