Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 21: Transport: Nanoelectronics I - Quantum Dots, Wires, Point Contacts 3
TT 21.9: Vortrag
Dienstag, 27. März 2012, 11:45–12:00, BH 334
Readout of carbon nanotube vibrations based on spin-phonon coupling — •Christoph Ohm4, Christoph Stampfer2,3, Janine Splettstoesser1, and Maarten R. Wegewijs1,3 — 1Institut für Theorie der Statistischen Physik, RWTH Aachen University, Germany — 2II. Physikalisches Institut B, RWTH Aachen University, Germany — 3Peter Grünberg Institut, Forschungszentrum Jülich, Germany — 4Institut für Quanteninformation, RWTH Aachen University, Germany
We theoretically study a carbon nanotube (CNT) double quantum dot consisting of a suspended and a non-suspended part. We propose a scheme for spin-based detection of the CNT bending motion in which the vibrational frequency is converted to a lower, more accessible frequency range. We make use of the spin-orbit coupling in CNTs. In the presence of vibrations, this yields a weak effective spin-phonon coupling. Classical vibrations of the CNTs are shown to induce a time dependent field acting on the electrons confined to the suspended dot, thereby generating spin flips. Within a rotating-wave approximation we find that the weakness of the spin-phonon coupling results in an effective down-mixing of the high vibrational frequency to a much lower spin-flip frequency. The latter can be controlled by the strength of an external magnetic field. We propose to read out the vibration-induced spin flips by measuring the leakage current through the double dot tuned to the spin-blockade regime as a function of the magnetic field. From a master equation we predict that the leakage current shows a pronounced peak allowing to read out the vibrational frequency.