41 research outputs found
High fidelity optical preparation and coherent Larmor precession of a single hole in an InGaAs quantum dot molecule
We employ ultrafast pump-probe spectroscopy with photocurrent readout to
directly probe the dynamics of a single hole spin in a single, electrically
tunable self-assembled quantum dot molecule formed by vertically stacking
InGaAs quantum dots. Excitons with defined spin configurations are initialized
in one of the two dots using circularly polarized picosecond pulses. The
time-dependent spin configuration is probed by the spin selective optical
absorption of the resulting few Fermion complex. Taking advantage of sub-5 ps
electron tunneling to an orbitally excited state of the other dot, we
initialize a single hole spin with a purity of >96%, i.e., much higher than
demonstrated in previous single dot experiments. Measurements in a lateral
magnetic field monitor the coherent Larmor precession of the single hole spin
with no observable loss of spin coherence within the ~300 ps hole lifetime.
Thereby, the purity of the hole spin initialization remains unchanged for all
investigated magnetic fields