Decoherence due to inelastic scattering from Kondo impurities

Y. Komijani, R. Yoshii, I. Affleck, Interaction effects in Aharonov-Bohm-Kondo rings, Phys. Rev. B 88, 245104 (2013) [Editor`s suggestion].

  • Magnetic moments are screened by the conduction electrons in a metal, the so-called Kondo effect. Scattering of other electrons off this Kondo-screened moment can be either elastic (top left) or inelastic (top right). Inelastic scattering randomizes the phase of the scattered electron, leading to decoherence.
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  • In this paper we study this effect on on a so-called Aharonov-Bohm-Kondo (ABK) ring (bottom figure). A quanutm dot (in the Kondo regime) is embedded in one of the arms of the ring and the Aharonov-Bohm oscillations through the ring is expected to be suppressed due to inelastic scattering from the Kondo moment. Here, we studied these effects in a small ABK ring.

Z. Shi, Y. Komijani, Conductance of closed and open long Aharonov-Bohm-Kondo rings, Phys. Rev. B 95, 075147 (2017).

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  • The study of decoherence effects in the small ABK ring mentioned above turn out to be inconclusive due to multipler scattering of the electrons as well as their multiple transverse along the ring.
  • Zheng (who gets most of the credit for this work) and I realized we can suppress these effects by allowing electrons to leak out to infinitiy and use this method to build a better which-path-detector. This, to some extend, was re-inventing the wheel: Amir Yacoby has already used this techniqe of open ring in his seminal experiment. We developed a technique to compute the conductance rigorously in arbitrary open/closed mesoscopic systems with a Kondo impurity.
  • Our results (right) show that indeed at zero temperature we have no dephasing, but increasing the temperature quickly suppresses the oscillations due to many-body dephasing.