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Register a new userRealization of a superconducting atom chip
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Authors
Thomas Nirrengarten
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We have trapped rubidium atoms in the magnetic field produced by a superconducting atom chip operated at liquid Helium temperatures. Up to $8.2cdot 10^5$ atoms are held in a Ioffe-Pritchard trap at a distance of 440 $mu$m from the chip surface, with a temperature of 40 $mu$K. The trap lifetime reaches 115 s at low atomic densities. These results open the way to the exploration of atom--surface interactions and coherent atomic transport in a superconducting environment, whose properties are radically different from normal metals at room temperature.
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We investigate the optical detection of single atoms held in a microscopic atom trap close to a surface. Laser light is guided by optical fibers or optical micro-structures via the atom to a photo-detector. Our results suggest that with present-day technology, micro-cavities can be built around the atom with sufficiently high finesse to permit unambiguous detection of a single atom in the trap with 10 $mu$s of integration. We compare resonant and non-resonant detection schemes and we discuss the requirements for detecting an atom without causing it to undergo spontaneous emission.
The coherence of quantum systems is crucial to quantum information processing. While it has been demonstrated that superconducting qubits can process quantum information at microelectronics rates, it remains a challenge to preserve the coherence and therefore the quantum character of the information in these systems. An alternative is to share the tasks between different quantum platforms, e.g. cold atoms storing the quantum information processed by superconducting circuits. In our experiment, we characterize the coherence of superposition states of 87Rb atoms magnetically trapped on a superconducting atom-chip. We load atoms into a persistent-current trap engineered in the vicinity of an off-resonance coplanar resonator, and observe that the coherence of hyperfine ground states is preserved for several seconds. We show that large ensembles of a million of thermal atoms below 350 nK temperature and pure Bose-Einstein condensates with 3.5 x 10^5 atoms can be prepared and manipulated at the superconducting interface. This opens the path towards the rich dynamics of strong collective coupling regimes.
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We give a comprehensive overview of the development of micro traps, from the first experiments on guiding atoms using current carrying wires in the early 1990s to the creation of a BEC on an atom chip.
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