Atom Chips are a new and exciting technology that enable the manipulation of atoms close to a chip surface. These chips combine cold atom physics with MEMS microfabrication techniques to create electric, magnetic and optical fields to trap and manipulate ultra-cold atom clouds.
The field of atom chips is a relatively new area of research which is rapidly becoming of great interest to the scientific community. It started out as a small branch of cold atom physics which has quickly grown into a multidisciplinary\nsubject. It now encompasses topics from fundamental atomic and quantum theory, optics and laser science, to the engineering of ultra sensitive sensors.\n\nIn this thesis the first steps are taken towards a truly integrated atom chip device for real world applications. Multiple devices are presented that allow the trapping, cooling, manipulation and counting of atoms. Each device presents a new component required for the integration and miniaturisation of atom chips\ninto a single device, capable of being used as a sensor.\n\nInitially, a wire trap was created capable of trapping and splitting a cloud of BoseEinstein condensate (BEC) for use in atom interferometry. Using this chip a BEC has been successfully created, trapped and coherent splitting of this cloud has been achieved.\n\nSubsequently, the integration and simplification of the initial trapping process was approached. In all the experiments to date, atoms are initially collected from a warm vapour by a magneto-optical trap (MOT). This thesis presents a new approach in which microscopic pyramidal MOTs’ are integrated into the chip itself. This greatly reduces the number of optical components and helps to simplify the process significantly.\n\nAlso presented is a method for creating a planar-concave micro-cavity capable of single atom detection. One such cavity consists of a concave mirror fabricated in silicon and the planar tip of an optical fibre. The performance of the resonators\nis highly dependent on the surface roughness and shape profile of the concave mirrors therefore a detailed study into the fabrication technique and its effects on these parameters was undertaken. Using such cavities single atom detection has been shown to be possible. These cavities have also been sccessfully integrated into an atom wire guide.\n\nFinally a co-sputtered amorphous silicon/titanium (a-Si/Ti) nanocomposite material was created and studied for its use as a novel structural material. This material is potentially suitable for integrated circuitry (IC)/Micro-electromechanical-\nsystems (MEMS) integration. The material’s electrical and\nstructural properties were investigated and initial results suggest that a-Si/Ti has the potential to be a compelling structural material for future IC/MEMS integration.\n\nTo build all of these devices, a full range of standard microfabrication techniques was necessary as well as some non standard processes that required considerable process development such as the electrochemical deposition.\n\nThis thesis presents a tool box of fabrication techniques for creating various components capable of different tasks that can be integrated into a single device. Each component has been successfully demonstrated in laboratory conditions. This represents a significant step toward a real world atom chip device.
Clouds of cold atoms, collected and refrigerated by laser light, can be cooled to nanoKelvin temperatures. This has created the new field of atom optics where cold atoms are manipulated, much as photons are controlled in traditional optics using mirrors, lenses, and gratings. It is also becoming possible to confine and manipulate atoms in extremely small traps and waveguides, which give access to de Broglie wave physical optics. Atoms flowing in such structures could provide a new technology based on the flow and quantum interactions of neutral atoms. Atom 'chips' could lead to integrated atom interferometers and even possibly to a quantum information processor.
Cold atoms promise versatile atomic chipsUsing a microelectronic chip to hold a cloud of cold atoms hovering above it, physicists in Germany may have developed an "atomic chip" that might eventually shunt Bose-Einstein condensates around an atom chip -just as electrons are shunted around a conventional silicon chip.This tiny circuit creates and manipulates a peculiar state of matter called a Bose-Einstein condensate (p21).Previously these condensates were made using light or magnetic fields to cool and confine a gas of atoms.Electric currents travelling through wires in the atom chip create a confining magnetic field barely 1 mm wide.This field holds a cloud of 1600 rubidium atoms at a height of less than a tenth of 1 mm above the chip surface.Quantum mechanics dictates that atoms, being so small, have wavelike properties.Normally each wave bobs up and down independently.However, in a Bose-Einstein condensate all of the atomic waves are "coherent" -moving in step, in the same quantum state.Instead of behaving like a
Summary form only given. Neutral-atom manipulation using integrated micro-devices is a new extremely promising experimental approach to QIPC. In devices we call Atom Chips, atoms are trapped or move in microscopic potentials above a surface. The traps, guides, are formed by potentials created using electric, magnetic and light fields which originate in (microscopic) structures built on the surface of the Atom Chip. To execute a QIPC toolbox we plan to implement quantum optics techniques using integrated micro devices fabricated on the Atom Chip. We describe our recent experimental progress towards this goal, demonstrating the realisation of traps and guides for neutral atoms on a nanofabricated chip.
The confinement and control of atomic clouds, at temperatures measured in nanokelvin, has become a valuable tool for physicists. As a source of new physics, development of cooling techniques has led to innovative new ways to probe the nature of reality. Of particular note are experiments carried out on new and exotic states of matter such as the Bose-Einstein condensate, unseen before the advent of these techniques. Likewise, the potential for applications outside of the lab is extensive and encompasses navigation, timekeeping, quantum communication and quantum computing. Manipulating cold atoms in the presence of a so-called ‘atom chip’ (a millimetre-scale electronic device) is currently considered the future of miniaturising these experiments and measurements, but since they still require precisely locked and stabilised lasers and predominantly must take place in the ultra-high vacuum regime, quantum control relies on an extensive and well-established infrastructure of optics, electronics, vacuum chambers and pumps. This encumbrance has slowed down the transition from chip-in-a-lab experiments to lab-on-a-chip technologies. This thesis is an account of work carried out in the development of enabling technologies which will accelerate this transition, including details of prototype devices made using established semiconductor and MEMS planar fabrication techniques. The construction and testing of an apparatus for anodically and eutectically bonding die-scale samples in ultra-high vacuum is described, along with an analysis and characterisation of some of its products.
The laser cooling, trapping and manipulating of neutral atoms has become a valuable tool for scientists, providing innovative ways to probe the nature of reality and giving rise to transformative devices in the fields of precise measurement and quantum information processing. Unlike traditional complex and bulky atomic experimental facilities, atom chips, through the design, fabrication of surface-patterned microstructures, and the integration of devices on the substrates, can precisely control the magnetic, electric or optical fields on a micro-nano scale with low power consumption. It can realize strong trapping as well as coherent atomic manipulation. Since atom chip was first proposed twenty years ago, it has built a robust quantum platform for miniaturizing and integrating quantum optics and atomic physics tools on a chip. In this paper, first, we briefly review the development history of atom chips, then introduce the basic knowledge of micro potential traps and micro guides based on on-chip current-carrying wires. Afterwards, the key technologies about the chip material, design, fabrication, characterization and integration of atom chips are discussed in detail. We not only focus on the currently most active and successful areas - current carrying wires, but also look at more visionary approaches such as to the manipulation of atoms with real nano structures, say, carbon nano tubes. The design and fabrication principles of ideal atom chips are discussed as well. In the forth part, the worldwide plans and research projects involving with atom chip technologies are summarized, showing that many countries see this as an important foundational technology. Following that, the major developments in the application fields including atom clocks, atom interferometer gyroscope, cold atom gravimeter, etc are described. Finally, the challenges faced by atom chips towards practical application are pointed out and the prospects for their subsequent development are depicted.