Ultrafast manipulation of electron spin coherence.
A technique is developed with the potential for coherent all-optical control over electron spins in semiconductors on femtosecond time scales. The experiments show that optical "tipping" pulses can enact substantial rotations of electron spins through a mechanism dependent on the optical Stark effect. These rotations were measured as changes in the amplitude of spin precession after optical excitation in a transverse magnetic field and approach pi/2 radians. A prototype sequence of two tipping pulses indicates that the rotation is reversible, a result that establishes the coherent nature of the tipping process.
Gupta
J A
JA
Department of Physics, University of California, Santa Barbara, CA 93106, USA.
Knobel
R
R
Samarth
N
N
Awschalom
D D
DD