Observation of Partial Coherence in an Aharonov-Bohm Interferometer with a Quantum Dot
H. Aikawa, K. Kobayashi, A. Sano, S. Katsumoto, and Y. Iye
Phys. Rev. Lett. 92 176802 (2004)
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We report experiments on the interference through spin states of electrons in a quantum dot (QD) embedded in an Aharonov-Bohm (AB) interferometer. We have picked up a spin-pair state, for which the environmental conditions are ideally similar. The AB amplitude is traced in a range of gate voltage that covers the pair. The behavior of the asymmetry in the amplitude around the two Coulomb peaks agrees with the theoretical prediction that the spin-flip process in a QD is related to the quantum dephasing of electrons. These results constitute evidence of "partial coherence" due to an entanglement of spins in the QD and in the interferometer.