We demonstrate single qubit operations on a trapped atom hyperfine qubit using a single ultrafast pulse from a mode-locked laser. We shape the pulse from the laser and perform a pi rotation of the qubit in less than 50 ps with a population transfer exceeding 99% and negligible effects from spontaneous emission or ac Stark shifts. The gate time is significantly shorter than the period of atomic motion in the trap (Rabi frequency / trap frequency > 10000), demonstrating that this interaction takes place deep within the strong excitation regime.
@article{arxiv.1005.4144,
title = {Ultrafast Gates for Single Atomic Qubits},
author = {W. C. Campbell and J. Mizrahi and Q. Quraishi and C. Senko and D. Hayes and D. Hucul and D. N. Matsukevich and P. Maunz and C. Monroe},
journal= {arXiv preprint arXiv:1005.4144},
year = {2010}
}