We demonstrate coherent control of a quantum dot exciton using photocurrent detection with a sinusoidal reverse bias. Optical control is performed at low bias, where tunneling-limited coherence times are long. Following this step, the tunneling rates are increased to remove the long-lived hole, achieving a high photocurrent signal. For a detection efficiency of 68%, electron and hole tunneling times during optical control of 200 ps and 20 ns can be achieved, compared to 120 ps and 7 ns for the constant bias case, respectively.
@article{arxiv.1305.2309,
title = {Enhanced photocurrent readout for a quantum dot qubit by bias modulation},
author = {J. H. Quilter and R. J. Coles and A. J. Ramsay and A. M. Fox and M. S. Skolnick},
journal= {arXiv preprint arXiv:1305.2309},
year = {2013}
}