Quantum Manipulation of Spins in Semiconductors
Semiconductor spintronics has the aim to develop functional devices for future (quantum-) information processing. We will address fundamental aspects, which are important for the performance of novel device concepts, especially for the creation and detection of spin-entangled electrons in semiconductor nanostructures. In the previous funding period, we have shown that any realistic detection scheme has to be carefully designed and that the use of higher-order correlation functions might be necessary for an unambiguous detection of entanglement. In the coming funding period we will continue to explore the effect of detector dynamics and back action on the transport of spin-entangled electrons in semiconductors, quantum channels and quantum dots. We will develop further the general scheme we have devised to detect quantum correlations using higher-order spin or current correlators. This will not only be useful in transport setups, but also for the recently developed spin-noise spectroscopy technique. It will enable the detection of quantum coherence, dephasing, and interaction between spins.p
- AG Belzig (Theoretische Physik mit SP Quantentransport)
|(2016): Photon-assisted electronic and spin transport in a junction containing precessing molecular spin Physical Review B. 2016, 93(7), 075402. ISSN 2469-9950. eISSN 2469-9969. Available under: doi: 10.1103/PhysRevB.93.075402
We study the ac charge and -spin transport through an orbital of a magnetic molecule with spin precessing in a constant magnetic field. We assume that the source and drain contacts have time-dependent chemical potentials. We employ the Keldysh nonequilibrium Green’s functions method to calculate the spin and charge currents to linear order in the time-dependent potentials. The molecular and electronic spins are coupled via exchange interaction. The time-dependent molecular spin drives inelastic transitions between the molecular quasienergy levels, resulting in a rich structure in the transport characteristics. The time-dependent voltages allow us to reveal the internal precession time scale (the Larmor frequency) by a dc conductance measurement if the ac frequency matches the Larmor frequency. In the low-ac-frequency limit the junction resembles a classical electric circuit. Furthermore, we show that the setup can be used to generate dc-spin currents, which are controlled by the molecular magnetization direction and the relative phases between the Larmor precession and the ac voltage.
|14.09.2011 – 13.09.2013