arXiv:cond-mat/0504209 · Physical Review A

Combined chips for atom optics

Andreas Günther, M. Kemmler, Sebastian Kraft, Chris J. Vale, Claus Zimmermann, József Fortágh

Published Jun 30, 2005• 73 citations

Abstract

We present experiments with Bose-Einstein condensates on a combined atom chip. The combined structure consists of a large-scale ``carrier chip'' and smaller ``atom-optics chips,'' containing micron-sized elements. This allows us to work with condensates very close to chip surfaces without suffering from fragmentation or losses due to thermally driven spin flips. Precise three-dimensional positioning and transport with constant trap frequencies are described. Bose-Einstein condensates were manipulated with submicron accuracy above atom-optics chips. As an application of atom chips, a direction sensitive magnetic-field microscope is demonstrated.

DOI: 10.1103/physreva.71.063619

Related papers

Bose–Einstein condensates in tailored micro potentials

József Fortágh

A combination of a large scaled 'carrier chip' and micron scaled 'atom-optics chips' is used for phase coherent manipulation Bose–Einstein condensates. Diffraction of condensates from a magnetic lattice potential is observed up to the fifth order.

Journal of Physics Conference SeriesJan 1, 20050 citations

Combined magnetic field system for atom chips

Xuemei Jia, Bowen Xu, Shuyu Zhou +1 more

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 [Formula: see text]Rb atoms in the magnetic trap is approximately [Formula: see text], 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.

Modern Physics Letters BDec 20, 20220 citations

Bose-Einstein condensation in a robust microtrap -- the combination of wire traps and atom chips

A. Kasper

In the presented work, we report about the successful creation of a Rubidium Bose-Einstein condensate. We use so called magnetic wire traps, which are especially simple, as they consist out of a wire and a homogeneous bias field. These wire traps are especially suited for Bose-Einstein condensation. Furthermore complex trapping potentials to manipulate a Bose-Einstein condensate can be realized. We combine 'large' and small scale wire traps. The 'large' scale is realized with a massive copper structure, while for the small wire traps we use the so called atom chip. This combination is promising, because it allowed us to develop a condensation process in the copper structure, which is independent of the structures on the atom chip, and thus the exchange of the 'physics' area. First experiments with the Bose-Einstein condensate are presented and discussed in detail.

Jan 1, 20041 citation

Bose-Einstein condensation on a permanent-magnet atom chip

Christopher D. J. Sinclair, E. A. Curtis, Isabel Llorente‐Garcia +5 more

We have produced a Bose-Einstein condensate on a permanent-magnet atom chip based on periodically magnetized videotape. We observe the expansion and dynamics of the condensate in one of the microscopic waveguides close to the surface. The lifetime for atoms to remain trapped near this dielectric material is significantly longer than above a metal surface of the same thickness. These results illustrate the suitability of microscopic permanent-magnet structures for quantum-coherent preparation and manipulation of cold atoms.

Physical Review ASep 21, 200575 citations

Bose-Einstein condensates on a magnetic film atom chip

S. Whitlock

Atom chips are devices used to magnetically trap and manipulate ultracold atoms and Bose-Einstein condensates near a surface. In particular, permanent magnetic film atom chips can allow very tight confinement and intricate magnetic field designs while circumventing technical current noise. Research described in this thesis is focused on the development of a magnetic film atom chip, the production of Bose-Einstein condensates near the film surface, the characterisation of the associated magnetic potentials using rf spectroscopy of ultracold atoms and the realisation of a precision sensor based on splitting Bose-Einstein condensates in a double-well potential. The atom chip itself combines the edge of a perpendicularly magnetised GdTbFeCo film with a machined silver wire structure. A mirror magneto-optical trap collects up to 5 x 108 87Rb atoms beneath the chip surface. The current-carrying wires are then used to transfer the cloud of atoms to the magnetic film microtrap and radio frequency evaporative cooling is applied to produce Bose-Einstein condensates consisting of 1 x 105 atoms. We have identified small spatial magnetic field variations near the film surface that fragment the ultracold atom cloud. These variations originate from inhomogeneity in the film magnetisation and are characterised using a novel technique based on spatially resolved radio frequency spectroscopy of the atoms to map the magnetic field landscape over a large area. The observations agree with an analytic model for the spatial decay of random magnetic fields from the film surface. Bose-Einstein condensates in our unique potential landscape have been used as a precision sensor for potential gradients. We transfer the atoms to the central region of the chip which produces a double-well potential. A single BEC is formed far from the surface and is then dynamically split in two by moving the trap closer to the surface. After splitting, the population of atoms in each well is extremely sensitive to the asymmetry of the potential and can be used to sense tiny magnetic field gradients or changes in gravity on a small spatial scale.

Jan 1, 20075 citations

Bose-Einstein condensation and surface effects on atom chips

Chris J. Vale

Ultra-cold neutral atoms and Bose-Einstein condensates (BECs) offer fascinating possibilities for quantum information processing. Long decoherence times, easy qubit addressing and the potential for scalability are some advantages. Storing and manipulating atoms in magnetic microtraps or 'Atom Chips' provides a promising base on which quantum logic operations could be performed. A primary source of decoherence in atom chip experiments arises from the interaction of the micro-Kelvin atoms with the room temperature chip surface. We have experimentally investigated these interactions and observe two interesting effects. Firstly, ultra-cold clouds are seen to fragment into clumps when brought within 100 microns of the chip surface. Secondly, the lifetime of atom clouds is seen to drop off near the surface due to spin flip transitions. These are caused by radio-frequency thermal fluctuations of the magnetic field as predicted but not previously observed.

Jan 1, 20030 citations