A technology to fabricate electrical contacts on individual single-wall car
bon nanotubes has been developed, and electrical measurements are carried o
ut below 4.2 Kelvin. The electrical transport property at low temperatures
has basically been characterized as a quantum dot with a pronounced Coulomb
blockade effect and zero dimensional confined levels. A microwave response
to the nanotube quantum dot is also studied to further characterize the qu
antum dot. It is discussed how and where the tunnel barrier is formed to re
alize the quantum dot in a sample. The microwave irradiation effect on the
quantum dot turns out to be a classical modulation of the source drain volt
age, and is discussed considering the various energy and time scales associ
ated with the transport.