Optical Interactions with Ground-State Spins in Semiconductors

Date: 
Tuesday, January 3, 2006 (All day)
Speaker: 
T. A. Kennedy

Systems that combine long-lived spin in the ground state with an allowed optical transition are interesting in themselves and potentially useful in optical and quantum-information applications.  Here I will discuss two such systems in semiconductor hosts.  The first is the NV center in diamond that has a very long-lived spin.  It can be polarized optically and its polarization can be detected through its luminescence.  Experiments manipulating the spin with microwave pulses show a phase-memory time of at least 58 microseconds at room temperature.   The second is an electron localized in a wide GaAs quantum well with an optical transition—the trion.  Experiments with picosecond pump and probe pulses reveal the simplest mechanism by which ground state coherence is excited.  The coherence lasts as long as a few nanoseconds.  Analysis of the results shows the importance of the hole spin-lifetime in determining the amount of coherence generated.