  Anomalous motional heating is a major obstacle to scalable quantum
information processing with trapped ions. While the source of this heating is
not yet understood, several previous studies suggest that surface contaminants
may be largely responsible. We demonstrate an improvement by a factor of four
in the room-temperature heating rate of a niobium surface electrode trap by in
situ plasma cleaning of the trap surface. This surface treatment was performed
with a simple homebuilt coil assembly and commercially-available matching
network and is considerably gentler than other treatments, such as ion milling
or laser cleaning, that have previously been shown to improve ion heating
rates. We do not see an improvement in the heating rate when the trap is
operated at cryogenic temperatures, pointing to a role of thermally-activated
surface contaminants in motional heating whose activity may freeze out at low
temperatures.
