Spin manipulation of free two-dimensional electrons in Si/SiGe quantum wells.
Understanding the mechanisms controlling the spin coherence of electrons in semiconductors is essential for designing structures for quantum computing applications. Using a pulsed electron paramagnetic resonance spectrometer, we measure spin echoes and deduce a spin coherence time (T2) of up to 3 mus for an ensemble of free two-dimensional electrons confined in a Si/SiGe quantum well. The decoherence can be understood in terms of momentum scattering causing fluctuating effective Rashba fields. Further confining the electrons into a nondegenerate (other than spin) ground state of a quantum dot can be expected to eliminate this decoherence mechanism.
Tyryshkin
A M
AM
Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 USA.
Lyon
S A
SA
Jantsch
W
W
Schäffler
F
F