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Driven quantum systems

Interaction-Induced Adiabatic Pumping Spectroscopy of Quantum Dots

 Adiabatic pumping through a nanostructure generally requires that two parameters are independently and periodically varied. However, when driving the gate and bias voltage of quantum dot, one still finds that the current may still vanish unless one accounts for the strong Coulomb interaction.

This interaction-induced pumping turns out to be a useful spectroscopic tool when plotting time-averaged versions of the well-known “Coulomb diamond” or “stability diagrams”. For instance, the sign of the low bias pumped charge turns out to carry information about the spin-degeneracy of the states. At high bias, this sign of this signal directly indicates the tunnel junction asymmetry. The pumped spin-current and pumping noise contain similar usefull information.

F. Reckermann, et. al., Phys. Rev. Lett. 104, 226803 (2010)
H. L. Calvo, L. Classen, et. al., Phys. Rev. B 86, 245308 (2012)
F. Haupt, et. al., Phys. Stat. Sol., online, (2013)

(M. R. Wegewijs)

 

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Readout of Carbon Nanotube Vibrations Based on Spin-Phonon Coupling

Spin-orbit interaction in carbon-nanotubes provides an intrinsic mechanism for detecting the vibrational state. The coupling to the bending of Marcus and Flensberg induces a spin-resonance in the transport current through a half-suspended nanotube when gated to form a Pauli-blockaded double quantum dot.

C. Ohm, C. Stampfer, J. Splettstoesser, and M. R. Wegewijs.. Appl. Phys. Lett., 100:143103, 2012.

(M. R. Wegewijs)

Readout-of-carbon-nanotube-vibrations_jpg


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