Controlling quantum systems by electrical current


In the project we investigated in the beginning the manipulation of entangled electron pairs in a superconducting multi-terminal device or a double quantum dot. We have found that the degree of entangled current can be tuned with the type of contact and the voltage configuration. To detect the entanglement we proposed to use signatures in the cross correlations and the super Poissonian noise. Using a ferromagnetic contact to a super­conductor a resonant subgap state can be induced at the interface, which can be manipulated by the bias voltage and leads to unique signatures in the differential conductance. The finite frequency noise is sensitive to the coherent oscillations and the relaxation of the quasi-bound state. Furthermore, we have investigated in detail, how an oscillating bias voltage influences the transport through a resonant level. The mean occupation can be increased as well as decreased, depending on the amplitude of the driving and the coherent oscillations lead to characteristic signatures in the noise spectral density. We have already performed preliminary calculations to address the spin properties and coherent spin-manipulation by a time-dependent magnetic field.

  • WG Belzig (Theoretische Physik mit SP Quantentransport)
Funding sources
Name Finanzierungstyp Kategorie Project no.
Deutsche Forschungsgemeinschaft third-party funds research funding program 538/08
Further information
Period: 01.01.2008 – 31.12.2011