We report microwave-driven photon-assisted tunneling in a suspended carbon nanotube double quantum dot. From the resonant linewidth at a temperature of 13 mK, the charge dephasing time is determined to be 280 +- 30 ps. The linewidth is independent of driving frequency, but increases with increasing temperature. The moderate temperature dependence is inconsistent with expectations from electron-phonon coupling alone, but consistent with charge noise arising in the device. The extracted level of charge noise is comparable with that expected from previous measurements of a valley-spin qubit, where it was hypothesized to be the main cause of qubit decoherence. Our results suggest a possible route towards improved valley-spin qubits.
@article{arxiv.1603.06278,
title = {Photon-assisted tunneling and charge dephasing in a carbon nanotube double quantum dot},
author = {Aquila Mavalankar and Tian Pei and Erik M. Gauger and Jamie H. Warner and G. Andrew D. Briggs and Edward A. Laird},
journal= {arXiv preprint arXiv:1603.06278},
year = {2016}
}