Coherent manipulation of coupled electron spins in semiconductor quantum dots.
We demonstrated coherent control of a quantum two-level system based on two-electron spin states in a double quantum dot, allowing state preparation, coherent manipulation, and projective readout. These techniques are based on rapid electrical control of the exchange interaction. Separating and later recombining a singlet spin state provided a measurement of the spin dephasing time, T2*, of approximately 10 nanoseconds, limited by hyperfine interactions with the gallium arsenide host nuclei. Rabi oscillations of two-electron spin states were demonstrated, and spin-echo pulse sequences were used to suppress hyperfine-induced dephasing. Using these quantum control techniques, a coherence time for two-electron spin states exceeding 1 microsecond was observed.
Petta
J R
JR
Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Johnson
A C
AC
Taylor
J M
JM
Laird
E A
EA
Yacoby
A
A
Lukin
M D
MD
Marcus
C M
CM
Hanson
M P
MP
Gossard
A C
AC