Tunable polarons in a carbon nanotube electromechanical resonator

We demonstrate the formation of polarons in a nanotube electromechanical resonator by increasing the effect of the electron-phonon
interaction to an unprecedented level. The polaronic nature of charge carriers results in the reduction of the electrical conductance by up to about half its value. The electron-phonon interaction suppresses the resonance frequency of the fundamental phonon mode by up to 25%. Our device is in the so-called ultra-strong coupling regime, where the electromechanical coupling per phonon is one order of magnitude
larger than the resonance frequency. Our work establishes nanotube resonator as a possible platform for the demonstration of mechanical quantum bits and the study of quantum interference effects in the movement of an object consisting of 10^5–10^6 atoms.