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In this paper, we have developed a combined magnetic field system to explore an alternative technical route for the generation of Bose–Einstein condensates containing numerous atoms on an atom chip. The system is characterized by the fact that the quadrupole magnetic field required by the magneto-optic trap is generated by U-shaped current-carrying wires combined with bias magnetic fields, whereas the quadrupole magnetic field adopted for the magnetic trap is generated by anti-Helmholtz coils. By fine-tuning the bias magnetic fields, the collection of atoms in the mirror MOT and the loading of the quadrupole magnetic trap can be optimized. The initial number of ${}^{87}$Rb atoms in the magnetic trap is approximately $1\times 10^8$, and the lifetime of the atoms is over 30 s. This scheme can facilitate the chip-surface design and is suitable for the precise manipulation of Bose–Einstein condensates near the chip surface.

The realization of quantum logic gates with neutral atoms on atom chips is investigated, including realistic features, such as noise and actual experimental setups.

We review recent progress at the Centre for Cold Matter in developing atom chips. An important advantage of miniaturizing atom traps on a chip is the possibility of obtaining very tight trapping structures with the capability of manipulating atoms on the micron length scale. We recall some of the pros and cons of bringing atoms close to the chip surface, as is required in order to make small static structures, and we discuss the relative merits of metallic, dielectric and superconducting chip surfaces. We point out that the addition of integrated optical devices on the chip can enhance its capability through single atom detection and controlled photon production. Finally, we review the status of integrated microcavities that have recently been demonstrated at our Centre and discuss their prospects for future development.

We report on the storage and manipulation of hundreds of mesoscopic ensembles of ultracold ⁸⁷Rb atoms in a vast two-dimensional array of magnetic microtraps, defined lithographically in a permanently magnetized film. The atom numbers typically range from tens to hundreds of atoms per site. The traps are optically resolved using absorption imaging and individually addressed using a focused probe laser. We shift the entire array, without heating, along the surface by rotating an external bias field. We evaporatively cool the atoms to the critical temperature for quantum degeneracy. At the lowest temperatures, density dependent loss allows small and well defined numbers of atoms to be prepared in each microtrap. This microtrap array is a promising novel platform for quantum information processing, where hyperfine ground states act as qubit states, and Rydberg excitation may orchestrate interaction between neighbouring sites.