Coherence and spin effects in quantum dots

This review focuses on experiments on coherent transport through quantum dot systems. The most important quantity obtained in coherent transport is the phase shift through the dots, which gives complementary information to the scattering amplitude ( i. e. the conductance). However, two- terminal devices have a particular difficulty, called 'phase rigidity', in obtaining the phase shift. There are two representative ways to avoid this problem: one is to adopt a multi-terminal configuration and another is to use resonance in the interferometer. This review mainly reviews the latter approaches. Such resonance in the whole interferometer often joins with local resonance inside the interferometer and appears as the Fano effect, which is a powerful tool for investigating the phase shift problem with the aid of theories. In addition to such resonances of single-electron states, electron spin causes a kind of many- body resonance, that is, the Kondo effect. Combination of these resonances is the Fano - Kondo effect. Experiments on the Fano - Kondo effect, which unveil the nature of the Kondo resonance, are also reviewed.