The spin property of electrons opens an alternative path to storing and processing information that may enable applications for low-power electronics and quantum computation. These applications typically require a long lifetime of non-equilibrium spin polarization and the possibility to interact quickly and controllably with the spins. By engineering the semiconductor material and using optical and transport experiments, we investigate how these sometimes opposing requirements can be met.
Spin-orbit interaction provides a very efficient mechanism that couples electron spins with an electric field. This enables fast spin rotations either by a gate voltage or by the electric field of a microwave mode. At the same time, fluctuations in the electric field or in the position of the electron may lead to undesirable dephasing of the electron spin. It is an important task to investigate the underlying physics and find ways to control and optimize both the desirable and the undesirable aspects of such spin interactions.
For spin-based quantum computing, one of the main challenges is to realize a strong long-range interaction between isolated spins. Most known methods — such as cavity quantum electrodynamics — rely on electric-dipole coupling, which does not directly involve the spin degree of freedom. Therefore, an additional step is needed: coupling an electric dipole to the spin. This can be done by employing spin-orbit interaction or by exchange interaction between double and triple quantum dots.
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