Prologue

Herewewill give a brief introduction to the chapters in this book.We

hope that this will help readers understand the concepts of quantum

transport and realize the difficult points.

First of all, let us specify the nanosystems in view of the nanometer-

scale length, 1 nm= 10−9 m. In this book, we treat the nanosystems with the length of approximately 1 nm ∼ 1 μm (= 1, 000 nm). Since the size of the atom is about 1 A˚ = 10−10 m = 0.1 nm, this corresponds to the length of 10 to 10,000 atoms in one direction.

Currently, there are two trends in the construction of nanometer-

scale systems in experiments.