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Register a new userMicroscopic atom optics: from wires to an atom chip
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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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We describe an experiment in which Bose-Einstein condensates and cold atom clouds are held by a microscopic magnetic trap near a room temperature metal wire 500 $mu$m in diameter. The ensemble of atoms breaks into fragments when it is brought close to the ceramic-coated aluminum surface of the wire, showing that fragmentation is not peculiar to copper surfaces. The lifetime for atoms to remain in the microtrap is measured over a range of distances down to $27 mu$m from the surface of the metal. We observe the loss of atoms from the microtrap due to spin flips. These are induced by radio-frequency thermal fluctuations of the magnetic field near the surface, as predicted but not previously observed.
Optical dipole traps and atom chips are two very powerful tools for the quantum manipulation of neutral atoms. We demonstrate that both methods can be combined by creating an optical lattice potential on an atom chip. A red-detuned laser beam is retro-reflected using the atom chip surface as a high-quality mirror, generating a vertical array of purely optical oblate traps. We load thermal atoms from the chip into the lattice and observe cooling into the two-dimensional regime where the thermal energy is smaller than a quantum of transverse excitation. Using a chip-generated Bose-Einstein condensate, we demonstrate coherent Bloch oscillations in the lattice.
We experimentally demonstrate optical spectroscopy of magnetically trapped atoms on an atom chip. High resolution optical spectra of individual trapped clouds are recorded within a few hundred milliseconds. Detection sensitivities close to the single atom level are obtained by photoionization of the excited atoms and subsequent ion detection with a channel electron multiplier. Temperature and decay rates of the trapped atomic cloud can be monitored in real time for several seconds with only little detection losses. The spectrometer can be used for investigations of ultracold atomic mixtures and for the development of interferometric quantum sensors on atom chips.
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.
We report an experiment of creating Bose-Einstein condensate (BEC) on an atom chip. The chip based Z-wire current and a homogeneous bias magnetic field create a tight magnetic trap, which allows for a fast production of BEC. After an 4.17s forced radio frequency evaporative cooling, a condensate with about 3000 atoms appears. And the transition temperature is about 300nK. This compact system is quite robust, allowing for versatile extensions and further studying of BEC.
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