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TT: Fachverband Tiefe Temperaturen

TT 29: TR: Nanoelectronics I: Quantum Dots, Wires, Point Contacts 1

TT 29.11: Vortrag

Donnerstag, 25. März 2010, 12:15–12:30, H19

Two-Particle Dark States in the Transport through Quantum Dot systems — •Christina Pöltl, Clive Emary, and Tobias Brandes — Institut für Theoretische Physik, Hardenbergstr. 36, D-10623 TU Berlin, Germany

Dark states (DSs) are originally a quantum optic phenomenon discovered as a dark line in the fluorescence of sodium atoms. The concept of the Dark states has been generalized to mesoscopic transport as coherent superpositions that block current flow. The triple quantum dot (TQD) in a triangular geometry is a system where several transport DS phenomena have been studied e.g. [1].

In this contribution, we apply bias such that both singly- and doubly- charged states participate in the transport through the TQD and focus on the formation of a two-electron DS [2].We discuss the conditions under which such a state forms and describe the signatures that it leaves in transport properties such as the differential conductance and shot noise. Our finite-bias calculations facilitate the experimental investigation of DS effects such as the break up of Coulomb blockade diamonds in the stability diagram of the TQD due to one- and two- electron DSs. However it shows that this two-electron DS is a product state of a spin-up and a spin-down single-particle DS. Therefore we also introduce a quantum dot system which allows to configure a spin entangled two-electron DS due to an exchange interaction between the electrons.

[1] B. Michaelis, et al. Europhys. Lett., 73, 677 (2006),

[2] C. Pöltl, et al. Phys. Rev. B 80, 115313 (2009)