Berezovsky*, J; Mikkelsen*, MH; Stoltz, NG; Coldren, LA; Awschalom, DD, *Picosecond coherent optical manipulation of a single electron spin in a quantum dot*,
Science, vol. 320 no. 349
(2008),
pp. 349-352 [doi] .
**Abstract:**

*Most schemes for quantum information processing require fast single-qubit operations. For spin-based qubits, this involves performing arbitrary coherent rotations of the spin state on time scales much faster than the spin coherence time. By applying off-resonant, picosecond-scale optical pulses, we demonstrated the coherent rotation of a single electron spin through arbitrary angles up to Ï€ radians. We directly observed this spin manipulation using time-resolved Kerr rotation spectroscopy and found that the results are well described by a model that includes the electron-nuclear spin interaction. Measurements of the spin rotation as a function of laser detuning and intensity confirmed that the optical Stark effect is the operative mechanism.*