Workshop book - Physikzentrum der RWTH Aachen - RWTH Aachen ...

Posters Tuesday February 5
Poster 40:
Magnetic field effects on the finite-frequency noise and ac conductance of a
Kondo quantum dot out of equilibrium
Sarah Müller
We present analytic results for the finite-frequency current noise and the
nonequilibrium ac conductance for a Kondo quantum dot in presence of a
magnetic field. We determine the line shape close to resonances and show
that while all resonances in the ac conductance are broadened by the transverse
spin relaxation rate; the noise at finite field additionally involves the
longitudinal rate as well as sharp kinks resulting in singular derivatives. Our
results provide a consistent theoretical description of recent experimental
data [Phys. Rev. Lett. 108, 046802 (2012)] for the emission noise at zero
magnetic field, and we propose the extension to finite field for which we
present a detailed prediction.
Poster 41:
Electron entanglement in Cooper pair beam splitter with magnetic fields
Stephan Weiss
We develop a theory that suggests the efficient manipulation of entangled
electrons provided by a Cooper pair beam splitter. The splitting of coherent
electrons forming a spin singlet is present if the superconductor is tunnel
coupled to a double quantum dot [1]. In order to probe entanglement, we
allow for an inhomogeneous and, in general, non-collinear magnetic field in
both dots. If the DQD-SC system is embedded in a transport setup, non-local
current and noise properties are obtained within the real-time diagrammatic
method [2]. As a small parameter we use the hybridization between splitter
and normal leads. The tunnel coupling to the superconductor is taken into
account non-perturbatively. Furthermore, we provide a detailed investigation
of the violation of Bell’s inequality for various parameter regimes.
[1] J. Eldridge, M. Governale, and J. König, Phys. Rev. B 82 184507, (2010).
[2] M. Governale, M. Pala, and J. König, Phys. Rev. B 77 134513, (2008).
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