Atom-chip Bose-Einstein condensation in a portable vacuum cell

A ⁸⁷Rb Bose-Einstein condensate (BEC) is produced in a portable atom-chip system less than 30×30×150.3em0excm, where the ultrahigh vacuum is maintained by a small, 80.3em0exL∕s, ion pump and nonevaporable getter. An aluminum nitride chip with lithographically patterned copper is used to seal the vacuum system, provide the electrical feedthroughs, and create the magnetic trap potentials. All cooling and trapping processes occur 0.6--2.50.3em0exmm from ambient laboratory air. A condensate of about 2000 ⁸⁷Rb atoms in F=2,mF=2 is achieved after 4.210.3em0exs of rf forced evaporation. A magneto-optical trap lifetime of 300.3em0exs indicates the vacuum near the chip surface is about 10^-100.3em0extorr. This work suggests that a chip-based BEC-compatible vacuum system can occupy a volume of less than 0.50.3em0exL.