Spin-flip reflection of electrons from a potential barrier in heterostructures

Spin-conserving and spin-flip opaque reflections of electrons from a potential barrier in heterostructures are described. An electric field of the barrier is considered to be the only source of energy spin splitting in the presence of spin-orbit interaction and its form is calculated in the three-level {\kp} model for a nontrival case of unbound electrons. Reflection angles and amplitudes are calculated for oblique incoming directions. It is shown that the system can serve as a source or filter of spin-polarized electron beams. Two unexpected possibilities are pointed out: a) non attenuated electron propagation in the barrier whose height exceeds the energies of incoming electrons, b) total reflection of electrons whose energies exceed barrier's height.Comment: 10 pages, 3 figure

Stability Diagram of a Few-Electron Triple Dot

Quantum dots are considered building blocks for future quantum information circuits. We present here experimental results on a quantum dot circuit consisting of three quantum dots with controlled electron numbers down to one per dot and tunable coupling. We experimentally map out for the first time the stability diagram of the triatomic system and reveal the existence of quadruple points, a signature of the three dots being in resonance. In their vicinity we observe a surprising effect, a 'cloning' of charge transfer transitions related to charge and spin reconfigurations. The experimental results are reproduced by equivalent circuit analysis and Hubbard models