Nonequilibrium current fluctuation is theoretically studied through a multilevel quantum dot in the Coulomb blockade regime, where the higher-order tunneling processes, "cotunneling," are dominant in the transport. The current fluctuation shows a Poisson (super-Poisson) noise in the elastic (inelastic) cotunneling regime when the bias voltage eV between the leads is smaller (larger) than the excitation energy Δ from the ground level in the quantum dot. The super-Poisson noise is remarkably enhanced by the degeneracy of the excited states around the beginning of inelastic cotunneling at eV ≈ Δ, qualitatively in good agreement with a recent experimental result. An analytical expression is given for the current fluctuation as a function of degeneracy.
|ジャーナル||Journal of Physics: Conference Series|
|出版ステータス||Published - 2017 8 15|
|イベント||33rd International Conference on the Physics of Semiconductors, ICPS 2016 - Beijing, China|
継続期間: 2016 7 31 → 2016 8 5
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