A 87 Rb Bose-Einstein condensate (BEC) is produced in a portable atom-chip system less than 30ϫ 30 ϫ 15 cm, where the ultrahigh vacuum is maintained by a small, 8 L / s, ion pump and nonevaporable getter. An aluminum nitride chip with lithographically patterned copper is used to seal the vacuum system, provide the electrical feedthroughs, and create the magnetic trap potentials. All cooling and trapping processes occur 0.6-2.5 mm from ambient laboratory air. A condensate of about 2000 87 Rb atoms in F =2,m F = 2 is achieved after 4.21 s of rf forced evaporation. A magneto-optical trap lifetime of 30 s indicates the vacuum near the chip surface is about 10 −10 torr. This work suggests that a chip-based BEC-compatible vacuum system can occupy a volume of less than 0.5 L.
We present a compact, transportable system that produces Bose-Einstein condensates (BECs) near the surface of an integrated atom microchip. The system occupies a volume of 0.4 m 3 and operates at a repetition rate as high as 0.3 Hz. Evaporative cooling in a chip trap with trap frequencies of several kHz leads to nearly pure condensates containing 1.9×10 4 87 Rb atoms. Partial condensates are observed at a temperature of 1.58(8) µK, close to the theoretical transition temperature of 1.1 µK.Since the first experimental demonstrations of BoseEinstein condensation (BEC) in a gas of neutral atoms, 1-3 studies of BEC and related forms of ultracold matter have been largely motivated by purely scientific interests. The complexity and size of the required apparatus necessitate that these experiments remain confined to research laboratories. However it has become increasingly evident that ultracold matter can play a utilitarian role in applications such as atomic clocks, inertial sensors, and electric and magnetic field sensing.4-9 Indeed, much of the work on ultracold atom chip technology is predicated on the need for compact systems that can find their way out of the laboratory and into the field.We present here a compact, movable, microchip-based BEC production system that occupies a volume of 0.4 m 3 , operates at a repetition rate as high as 0.3 Hz, and produces BECs containing 1.9×10 4 atoms in the |F = 2, m F = 2 ground state of 87 Rb (see Fig. 1). The system contains all of the components needed to produce and image BECs, including an ultra-high vacuum (UHV) system, lasers, data acquisition hardware, electronics, and imaging equipment. The system can be easily reconfigured for use with atom chips having unique wire patterns designed for different applications. As such, it can serve as a standardized platform for a variety of portable experiments that utilize ultracold matter.
We describe the design and function of a circular magnetic waveguide produced from wires on a microchip for atom interferometry using deBroglie waves. The guide is a two-dimensional magnetic minimum for trapping weak-field seeking states of atoms or molecules with a magnetic dipole moment. The design consists of seven circular wires sharing a common radius. We describe the design, the time-dependent currents of the wires and show that it is possible to form a circular waveguide with adjustable height and gradient while minimizing perturbation resulting from leads or wire crossings. This maximal area geometry is suited for rotation sensing with atom interferometry via the Sagnac effect using either cold atoms, molecules and Bose-condensed systems
We demonstrate a two dimensional grating magneto-optical trap (2D GMOT) with a single input cooling laser beam and a planar diffraction grating using 87 Rb. This configuration increases experimental access when compared with a traditional 2D MOT. As described in the paper, the output flux is several hundred million rubidium atoms/s at a mean velocity of 16.5(9) m/s and a velocity distribution of 4(3) m/s standard deviation. We use the atomic beam from the 2D GMOT to demonstrate loading of a three dimensional grating MOT (3D GMOT) with 2.46(7) × 10 8 atoms. Methods to improve output flux are discussed.
We present a method for generating precise, dynamically tunable magnetic potentials that can be described by a polynomial series along the axis of a cold-atom waveguide near the surface of an atom chip. With a single chip design consisting of several wire pairs, various axial potentials can be created by changing the ratio of the currents in the wires, including double wells, triple wells, and pure harmonic traps with suppression of higher-order terms. We use this method to design and fabricate a chip with modest experimental requirements. Finally, we use the chip to demonstrate a double-well potential.
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