We demonstrate high speed manipulation of a few-electron double quantum dot. In the one-electron regime, the double dot forms a charge qubit. Microwaves are used drive transitions between the (1,0) and (0,1) charge states of the double dot. A local quantum point contact charge detector measures the photon-induced change in occupancy of the charge states. Charge detection is used to measure T1~16 ns and also provides a lower bound estimate for T2* of 400 ps for the charge qubit. In the two-electron regime we use pulsed-gate techniques to measure the singlet-triplet relaxation time for nearly-degenerate spin states. These experiments demonstrate that the hyperfine interaction leads to fast spin relaxation at low magnetic fields. Finally, we discuss how two-electron spin states can be used to form a logical spin qubit.
@article{arxiv.cond-mat/0510151,
title = {Charge and spin manipulation in a few-electron double dot},
author = {J. R. Petta and A. C. Johnson and J. M. Taylor and A. Yacoby and M. D. Lukin and C. M. Marcus and M. P. Hanson and A. C. Gossard},
journal= {arXiv preprint arXiv:cond-mat/0510151},
year = {2010}
}
Comments
Presented at EP2DS-16, to be published in Physica E