  We demonstrate and characterize the transfer of a levitating silica
nanosphere between two optical tweezers, at low pressure. Both optical traps
are mounted on the heads of optical fibers and placed on translation stages in
vacuum chambers. Our setup allows to physically separate the particle loading
environment from the experimental chamber, where the second tweezer can
position the particle inside a high Finesse optical cavity. The separation
prevents from spoiling the cavity mirrors and the chamber cleanliness during
the particle loading phase. Our system provides a very reliable and simply
reproducible protocol for preparing cavity optomechanics experiments with
levitating nanoparticles, opening the way to systematic studies of quantum
phenomena and easing the realization of sensing devices.
