
Lab. Info.
The recent advances in lithographic technology have enabled physicists to fabricate and control nanoscale systems. As a result, the integerand fractioinal quantum Hall effects were discovered in twodimensionalelectron gas systems in 1980's, and mesoscopic physics has been activelyinvestigated since 1990's. Moreover, around 1995, researchers wereable to study electronic nanocircuits, where electrical current can flow through single atom or single molecule. Electrons in this kind of smallsystems are governed by quantum mechanics and can strongly interact witheach other. These facts give rise to a variety of novel pheonomena inmesoscopic systems, especially those relating to electronic transport.Currently, new topics in mesoscopic physics are emerging, connecting withother physics research areas such as quantum chaos, spintronics, nanomechanics, nanoelectronics, and quantum information. In our laboratory, we are theoretically studying mesoscopic physics. The detailed topics can be found below or in the group webpage linked at the bottom of this page.

Mesoscopic physics
The mesoscopic systems are intermediate between statistical macroscopic and quantum mechanical microscopic length scales. In these systems, electron motions are phase coherent and thus governed by quantum mechanics, and there can be often many electrons, which requires statistical treatment. Mesoscopic systems can be classified by their dimension, such as twodimenionsl electron gas (2DEG), quantum wires (1D), and quantum dots (0D). The detailed topics studied in our Lab. are as follows:
 Phasecoherent electron transport and conductance quantization
 Quantum billiard and disordered system (related to quantum chaos)
 Spin control (related to spintronics)
 Entanglement (related to quantum information and computation)
 Decoherence

Electron correlation in low dimensional systems
One of the most important open problems in condensed matter physics is to understand strongly correlated electrons. Mesoscopic systems provide a good playground for studying electron correlations, since electronelectron interactions are stronger in lower dimensional systems and one can experimentally control the properties of mesoscopic systems. The detailed phenomena studied in our Lab. are:
 Coulomb blockade and Kondo effect (0D)
 Luttinger liquid (1D)
 Fractional quantum Hall effect (2D)
 Mesoscopic superconductivity

Nanoscale electron transport
The smallest conductor in our world is maybe single atom or single molecule. In this kind of small conductors, the classical Ohm's law does not work any more. Instead, one requires a new formalism, which takes into account of quantum mechanical properties such as discreteness of electron charge, Pauli principle, electronelectron interactions, etc. The systems studied in our Lab. are:
 Atomicsize contact and atomic wire
 Carbon nanotube and molecular electronics
