Trapping ultracold atoms on microchips with either electric or magnetic fields could lead to miniature atomic clocks and improved sensors, but the fluctuating fields in such small structures cause loss of coherence and degraded performance. One solution is to use superconductors to generate the trapping fields, which reduces several sources of noise. Type-II superconductors are especially interesting because they support the formation of vortices whose magnetic fields can be combined with applied fields to create minima in the field pattern that will trap atoms.
Reporting their results in Physical Review A, Bo Zhang and colleagues at Nanyang Technological University, Singapore, the National University of Singapore, and Rowan University in New Jersey, US, have performed calculations on various designs of type-II superconducting traps. Zhang et al. consider the case of an infinitely long superconducting strip with a magnetic field applied perpendicularly to the strip surface and compute various field configurations for different distributions of supercurrents and vortices. They find that the type-II materials offer impressive versatility in achieving desired magnetic field patterns, making them attractive for microtrapping. – David Voss