Optical fabrication and trapping of microspheres in cryogenic conditions

Cryogenic conditions suppress Brownian motion of microparticles to enable them to be trapped strongly. We fabricated and magnetically trapped superconducting microspheres through Meissner effect in superfluid helium. In addition, temperature dependence of the motion of the trapped particles in normal helium liquid and helium gas and the critical temperature of the superconductivity was investigated. We also report on the fabrication and optical trapping of semiconductor microspheres in superfluid helium.