Arrays of magnetic microtraps for quantum information science
In this project we produce magnetic lattices of microtraps on an atom chip. These chips are based on permanently magnetised films of FePt, and are patterned by lithography. We have pioneered this technique which can be considered an alternative to optical lattices. Magnetic-film atom chips are particularly suitable to create two-dimensional (2D) lattices, in essentially arbitrary geometries and length scales.
In previous experiments we demonstrated lattices of hundreds of traps, each containing a few hundred ultracold Rb atoms. We cooled these mesoscopic ensembles to quantum degeneracy by forced RF evaporation and shuttled the atoms along the chip surface like in a shift register.
We are presently working with square and hexagonal lattices with a 10 micron lattice spacing. Our motivation is to develop these magnetic chip lattices as a novel, scalable platform for quantum information science. The main idea is to store quantum information in coherent superpositions of ground state hyperfine levels of ultracold 87Rb atoms. Interactions will be induced by transient excitation to highly excited Rydberg energy levels.
In this approach we thus separate the storage of information from its processing. Information is stored in long-lived ground states, and processed by interactions on demand between Rydberg atoms. The length scale of 10 μm is compatible with Rydberg interaction and at the same time easy to resolve optically, so that individual sites can be addressed. This is further facilitated by the intrinsic 2D nature of these lattices.
In parallel we are also investigating the scaling down of magnetic lattices to well below the wavelength of visible light, possibly down to 100 nm lattice spacing. This will result in very strong tunnelling rates between the nanotraps and open up new regimes in quantum simulation of for example Bose-Hubbard type models.