  Fabrication of Nano-Electro-Mechanical-Systems (NEMS) of high quality is
nowadays extremely efficient. These NEMS will be used as sensors and actuators
in integrated systems. Their use however raises questions about their interface
(actuation, detection, read out) with external detection and control systems.
Their operation implies many fundamental questions related to single particle
effects such as Coulomb blockade, light matter interactions such as radiation
pressure, thermal effects, Casimir forces and the coupling of nanosystems to
external world (thermal fluctuations, back action effect). Here we specifically
present how the damping of an oscillating cantilever can be tuned in two
radically different ways: i) through an electro-mechanical coupling in the
presence of a strong Johnson noise, ii) through an external feedback control of
thermal fluctuations which is the cold damping closely related to Maxwell's
demon. This shows how the interplay between MEMS or NEMS external control and
their coupling to a thermal bath can lead to a wealth of effects that are
nowadays extensively studied in different areas.
