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Double-dot charge qubit and transport via dissipative cotunneling

Mei-Rong Li·Karyn Le Hur
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Abstract

We investigate transport through an exotic ``charge'' qubit composed of two strongly capacitively coupled quantum dots (QDs), each being independently connected to a side gate which in general exhibits a fluctuating electrostatic field ({\em i.e.}, Nyquist/Johnson noise). Two quantum phases are found: the ``Kondo'' phase where an orbital-Kondo entanglement emerges and a ``local moment'' phase in which the noise destroys the Kondo effect leaving the orbital spin unscreened and resulting in a clear suppression of the conductance. In the Kondo realm, the transfer of charge across the setting is accompanied by zero-point charge fluctuations in the two dissipative environments and then the I-V characteristics are governed by what we call ``dissipative cotunneling''.

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Mei-Rong Li, Karyn Le Hur. 2004-12-21. Double-dot charge qubit and transport via dissipative cotunneling. https://doi.org/10.1103/physrevlett.93.176802

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