May 11, 2009

Physicists make smallest incandescent lamp

U.S. scientists say they have created the world's smallest incandescent lamp to explore the boundary between thermodynamics and quantum mechanics.

The UCLA researchers said thermodynamics concerns systems with many particles while quantum mechanics works best when applied to just a few. The team is using its tiny lamp to study physicist Max Planck's black-body radiation law, which was derived in 1900 using principles now understood to be native to both theories.

The scientists said their incandescent lamp utilizes a filament made from a single carbon nanotube that is only 100 atoms wide. To the unaided eye, the filament is completely invisible when the lamp is off, but it appears as tiny point of light when the lamp is turned on.

With less than 20 million atoms, the nanotube filament is both large enough to apply the statistical assumptions of thermodynamics and small enough to be considered as a molecular, or quantum mechanical, system.

The study led by Chris Regan of the university's California NanoSystem's Institute that also included Yuwei Fan, Scott Singer and Ray Bergstrom was reported in the May 5 online edition of the journal Physical Review Letters.