Spin-flip Process and Quantum Decoherence in a Quantum Dot
H. Aikawa, K. Kobayashi, A. Sano, S. Katsumoto, and Y. Iye
We studied coherence of electrons traversing a quantum dot (QD) by using an Aharonov-Bohm (AB) interferometer. It was found that for the so-called ``spin-pair'' peaks of Coulomb oscillations the amplitude of the AB oscillation is different between one and the other side of each peaks and that the amplitude is smaller for the sides facing with each other than the outer ones. Similar result was obtained for a QD in the Kondo state. These observations agree with the theoretical model that relates a spin-flip process of traversing electrons through a QD to the decoherence.