If an atomic vapour of bosons is cold and dense enough that the inter-atomic spacing approaches the thermal de Broglie wavelength, then a phase transition occurs and all of the atoms coalesce into the same (lowest energy) quantum state. Such a Bose-Einstein condensate (BEC), in which all of the atoms behave in essentially the same way, is thus the atomic analogue of a laser – an atom laser. These atom lasers are extremely cold (~10nK) coherent macroscopic quantum objects large enough to be observed on a simple CCD camera – bringing textbook quantum mechanics to life. Achievements in the field to date ensured the 2001 Nobel Physics Prize for those who first experimentally realised BEC. BEC phase transitionInterference fringes: black=atoms, white=no atoms
In 2003 we created the first Bose-Einstein condensate (BEC) in Scotland at Strathclyde, joining other groups worldwide. Our condensate contains about 5 105 87Rb atoms in the |F=2,mF=2> state. The BEC was created at a localised position at the top of our storage ring, and in 2005 was one of the first experiments in the world to observe BEC propagation in a ring. We can also split the condensate into two halves which rotate in opposite directions around the ring. Recently we revisited a classic MIT experiment and made the equivalent of a matter wave Young’s slits interferometer.

Images from the BEC experiment


  • Y. Zhai, C.H. Carson, V.A. Henderson, P.F. Griffin, E. Riis and A.S. ArnoldTalbot-enhanced, maximum-visibility imaging of condensate interferenceOptica 5, 80-85 (2018).
  • M.E. Zawadzki, P.F. Griffin, E. Riis, and A.S. Arnold, Spatial interference from well-separated split condensatesPhys. Rev. A 81, 043608 (2010).
  • N. Houston, E. Riis and A.S. Arnold, Reproducible dynamic dark ring lattices for ultracold atoms, J. Phys. B 41, 211001 (2008).
  • A.S. Arnold, C.S. Garvie, and E. Riis, Large magnetic storage ring for Bose-Einstein condensates, Phys. Rev. A 73, 041606(R), (2006).
  • C.S. Garvie, E. Riis and A. S. Arnold, A storage ring for Bose-Einstein condensates, in “Laser Spectroscopy XVI,” P. Hannaford et al. eds., p178, (World Scientific, Singapore, 2004).
  • A.S. Arnold and E. Riis, Bose-Einstein condensates in ‘giant’ toroidal magnetic traps, J. Mod. Opt. 49, 959 (2002).