Control of quantum beats from electron spin coherence in semiconductor quantum wells

We demonstrate a spin manipulation scheme that controls the amplitude as well as the phase of the quantum beats from electron spin coherence by exploiting the relative phase between relevant Larmor precessions and by tipping the precessing spin at a specified time. Theoretical analyses using a phenomenological N-exciton eigenstate model indicate that the spin manipulation scheme can take advantage of the underlying exciton-exciton interactions inherent in a semiconductor and can be more effective in an excitonic system than in a corresponding atomiclike system.