Nanotubes get as small as they can

Advanced electronics and other microscopic devices might someday depend on carbon nanotubes—minuscule rolls each made of a cylindrical layer of carbon atoms.

Now, two research teams have created stable carbon nanotubes with the smallest diameter that scientists believe is physically possible. At merely 0.4 nanometer across, they don’t even span the width of four hydrogen atoms lined up next to one another.