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arXiv · 1008.1262

Quantum Phase Transition and Dynamically Enhanced Symmetry in Quadruple Quantum Dot System

Dong E. Liu·Shailesh Chandrasekharan·Harold U. Baranger
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Abstract

We propose a system of four quantum dots designed to study the competition between three types of interactions: Heisenberg, Kondo and Ising. We find a rich phase diagram containing two sharp features: a quantum phase transition (QPT) between charge-ordered and charge-liquid phases, and a dramatic resonance in the charge liquid visible in the conductance. The QPT is of the Kosterlitz-Thouless type with a discontinuous jump in the conductance at the transition. We connect the resonance phenomenon with the degeneracy of three levels in the isolated quadruple dot and argue that this leads to a Kondo-like dynamical enhancement of symmetry from U(1) x Z_2 to U(1) x U(1).

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Dong E. Liu, Shailesh Chandrasekharan, Harold U. Baranger. 2010-08-06. Quantum Phase Transition and Dynamically Enhanced Symmetry in Quadruple Quantum Dot System. https://doi.org/10.1103/physrevlett.105.256801

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