In this work, Press et al. demonstrate the use of ultrafast (~2 picosecond) pulses to manipulate an electron spin trapped in a quantum dot. The paper shows that full rotations about one spin axis can be made using such pulses, and that in combination with Larmor precession caused by the application of a large, static magnetic field, it is possible to manipulate the spin to point in any direction on the Bloch sphere in less than 50 picoseconds.
Figure 1. The energy level structure of the quantum dot spin system, and the experimental setup.
Figure 2. Rabi oscillations from the ultrafast control technique, which directly show how increased angles of rotation about one spin axis can be achieved by simply increasing the optical power of the rotation pulses.
Dr. David Press
Kristiaan De Greve
Dr. Thaddeus Ladd
Prof. Yoshihisa Yamamoto