Welcome to Condensed Matter Physics
Last Update: May.18, 2006
"Physics Lab.2006", which consists of the students majoring in physics at The University of Tokyo, releases the results of our study in the way that the visitors can enjoy the physics. Our group's theme of this year is "the quantization of conductance" and "the boiling surpression of liquid nitrogen".
The quantization of conductance is one of the phenomena unique to the mesoscopic system. Since the mesoscopic system is a nanometer-sized system, the quantum mechanical effect cannot be ignored, so the phenomena that do not conform to our feeling happen. The excellent point is that you can study and check with freely designed systems whether they agree with the theoretical prediction or not. The mesoscopic system is one of the hottest topics in the modern condensed matter physics.
The conductance is defined as the ability of the material to carry the electricity. It takes discrete values in the mesoscopic scale whereas in the macroscopic wire it varies proportionally to the thickness (of course continuously). When we think about this result, we have to reconsider the question: "In the first place what does it mean the electricity is easy to flow? What is the conductance? And why discrete values?" We do experiments concerning the quantization of conductance by using semiconductors and metal nanowires to answer these questions and speculate about the mesoscopic system.
We also study the boiling surpression of liquid nitrogen. We pick up this experiment because you can easily see what is happening and it is possible to give it an explanation using only the fundamental knowledge. The boiling point of liquid nitrogen is -196C, so it is naturally boiling under the environment at the room temperature (about 20C). But you can stop the boiling for a while by putting helium gas in liquid nitrogen. Imagine the case of boiling water, and you will find how mysterious this phenomenon is. The reason of the boiling stop was not known, but we have elucidated the mechanism through a series of experiments!
We are looking forward to your visiting. Enjoy seeing and touching the laboratory apparatus.
Leader of condensed matter physics group