In physical systems, decoherence can arise from both dissipative and dephasing processes. In mechanical resonators, the driven frequency response measures a combination of both, while time domain techniques such as ringdown measurements can separate the two. Here, we report the first observation of the mechanical ringdown of a carbon nanotube mechanical resonator. Comparing the mechanical quality factor obtained from frequency- and time-domain measurements, we find a spectral quality factor four times smaller than that measured in ringdown, demonstrating dephasing-induced decoherence of the nanomechanical motion. This decoherence is seen to arise at high driving amplitudes, pointing to a non-linear dephasing mechanism. Our results highlight the importance of time-domain techniques for understanding dissipation in nano-mechanical resonators, and the relevance of decoherence mechanisms in nanotube mechanics.
@article{arxiv.1503.06815,
title = {Observation of decoherence in a carbon nanotube mechanical resonator},
author = {Ben H. Schneider and Vibhor Singh and Warner J. Venstra and Harold B. Meerwaldt and Gary A. Steele},
journal= {arXiv preprint arXiv:1503.06815},
year = {2015}
}