Noise spectra of ac-driven quantum dots: Floquet master-equation approach

B. H. Wu and C. Timm
Phys. Rev. B 81, 075309 – Published 9 February 2010

Abstract

We study the transport properties of a quantum dot driven by either a rotating magnetic field or an ac gate voltage using the Floquet master-equation approach. Both types of ac driving lead to photon-assisted tunneling where quantized amounts of energy are exchanged with the driving field. It is found that the differential-conductance peak due to photon-assisted tunneling does not survive in the Coulomb-blockade regime when the dot is driven by a rotating magnetic field. Furthermore, we employ a generalized MacDonald formula to calculate the time-averaged noise spectra of ac-driven quantum dots. Besides the peak at zero frequency, the noise spectra show additional peaks or dips in the presence of an ac field. For the case of an applied ac gate voltage, the peak or dip position is fixed at the driving frequency whereas the position changes with increasing amplitude for the case of a rotating magnetic field. Additional features appear in the noise spectra if a dc magnetic field is applied in addition to a rotating field. In all cases, the peak or dip positions can be understood from the energy differences of two available Floquet channels.

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  • Received 30 October 2009

DOI:https://doi.org/10.1103/PhysRevB.81.075309

©2010 American Physical Society

Authors & Affiliations

B. H. Wu1,2,* and C. Timm3,†

  • 1Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01087 Dresden, Germany
  • 2State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, 865 Changning Road, Shanghai 200050, China
  • 3Institute for Theoretical Physics, Technische Universität Dresden, 01062 Dresden, Germany

  • *bhwu@mail.sim.ac.cn
  • carsten.timm@tu-dresden.de

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Issue

Vol. 81, Iss. 7 — 15 February 2010

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