This paper focuses on several key ideas to using atom interferometry to detect rotation within the context of an atom trap or “guide”. I discuss shortcomings of traditional free space light pulse atom interferometry that the advantages of guided light pulse atom interferometry can mitigate and under what conditions that strategy is possible. There is discussion of requirements for the light pulses, and the properties of the waveguide that will be needed for guided atom interferometry to successfully improve on the capability of free space light pulse atom interferometry.
This paper focuses on several key ideas to using atom interferometry to detect rotation within the context of an atom trap or “guide”. I discuss shortcomings of traditional free space light pulse atom interferometry that the advantages of guided light pulse atom interferometry can mitigate and under what conditions that strategy is possible. There is discussion of requirements for the light pulses, and the properties of the waveguide that will be needed for guided atom interferometry to successfully improve on the capability of free space light pulse atom interferometry.
Atom optics has been a highly active field of research with many scientific breakthroughs over the past two decades, largely due to successful advances in laser technology, microfabrication techniques, and the development of laser cooling and trapping of neutral atoms. This dissertation details several atom optics experiments with the motivation to develop tools and techniques for precision atom wave interferometry. It provides background information about atom optics and the fundamentals behind laser cooling and trapping, including basic techniques for cold gas thermometry and absorptive detection of atoms. A brief overview of magnetic trapping and guiding in tight wire-based traps is also provided before the experimental details are presented. ❧ We developed a novel laser source of 780 nm light using frequency-doubled 1560 nm fiber amplifier. This laser system provided up to a Watt of tunable frequency stabilized light for two Rb laser cooling and trapping experiments. One system generates Bose-Einstein condensates in an optical trap while the second is based on atom chip magnetic traps. The atom chip system, detailed in this thesis, was designed and built to develop the tools necessary for transport and loading large numbers of cold atoms and explore the potential for guided atom interferometry. Techniques and results from this experiment are presented, including an efficient magnetic transport and loading method to deliver cold atom to atom chip traps. We also developed a modeling tool for the magnetic fields formed by coiled wire geometries, as well as planar wire patterns. These models helped us design traps and determine adiabatic transportation of cold atoms between macro-scale traps and micro-traps formed on atom chips. Having achieved near unity transfer efficiency, we demonstrated that this approach promises to be a consistent method for loading large numbers of atoms into micro-traps. Furthermore, we discuss an in situ imaging technique to investigate magnetic field contours of the traps and the dynamics of atoms within those confining potentials. We also controlled the propagation along the atom chip guides by accelerating atoms with longitudinal magnetic gradients, and investigated an atom focusing scheme. ❧ While the atom chip wire guides perform a role analogous to optical fibers guiding light waves, ""free space"" cold atoms offer great opportunity for precision interferometry. We describe a second on-going atom optics experiment that measures gravity gradients using a pair of atom fountain interferometers separated by one meter. We have demonstrated Gravity Gradiometer resolution down to 4x10⁻⁹ g/m using a 40 kg test mass. The atomic physics subsystem is described in detail, including the vacuum, cold atom source, optics, magnetic coils and shields, and vibration isolation and compensation. The system is designed to be a compact, robust, transportable instrument, taking strides towards future gravity gradient measurements in the field. In the realm of space applications, there has been interest for micro-gravity science experiments aboard the International Space Station, along with instrument development for gravity mapping of Earth and planetary bodies with satellite-based instruments. Furthermore, there are ground-based applications for gravity imaging of local density distributions, precision measurement of gravity, as well as proposals for redefining the kilogram, detecting gravitational waves and determining the Gravitational constant.
Abstract : Gyroscopes based on ultracold atom interferometry have the potential to exhibit an intrinsic sensitivity larger by a factor of 4 x 1010 than for light-based interferometers. One of the major technical challenges for the advancement of atom optics and development of practical guided matter wave interferometers is the realization of coherent beam splitters. The overall focus of our research program is to develop a physical understanding of the conditions needed for coherent beam splitting and transport and use this knowledge to implement atom chip based interferometers using clouds of ultracold atoms. In this report we describe our experimental apparatus in detail and discuss the current progress towards interferometric measurements with clouds of ultracold atoms in a chip-based magnetic waveguide.
This work reviews the topic of rotation sensing with compact cold atom interferometers. A representative set of compact free-falling cold atom gyroscopes is considered because, in different respects, they establish a rotation-measurement reference for cold guided-atom technologies. This review first discusses enabling technologies relevant to a set of key functional building blocks of an atom chip-based compact inertial sensor with cold guided atoms. These functionalities concern the accurate and reproducible positioning of atoms to initiate a measurement cycle, the coherent momentum transfer to the atom wave packets, the suppression of propagation-induced decoherence due to potential roughness, on-chip detection, and vacuum dynamics because of its impact on sensor stability, which is due to the measurement dead time. Based on the existing enabling technologies, the design of an atom chip gyroscope with guided atoms is formalized using a design case that treats design elements such as guiding, fabrication, scale factor, rotation-rate sensitivity, spectral response, important noise sources, and sensor stability.
This consortium has initiated a focused collaborative program to advance matter wave sensors. We seek to combine atom interferometry with atom lasers and atom waveguides with the prospect of improving the sensitivity of such sensors by orders of magnitude as compared with existing state-of-the-art sensors. We will identify, explore and exploit fundamental scientific possibilities surrounding the production, manipulation and detection of ultra-cold atoms for a variety of sensing applications. Such sensors include gravimeters, gravity gradiometers, gyroscopes, magnetometers and frequency standards and have applications in science and technology and within the DOD. Sensitive and accurate inertial force sensors can be used in covert/passive navigation, precision guidance, underground structure detection, gravitational mapping, etc. They are non-emanating and capable of operating in a jammed-GPS environment. We seek to build awareness of DOD needs critical to national defense at the graduate training level, and to establish a dialogue between DOD and industrial researchers/managers and PhD trainees. The institutions identified in the proposed consortium attract talented students who are likely to become future leaders in science and technology.
We discuss a scheme to implement a gyroscopic atom sensor with magnetically trapped ultra-cold atoms. Unlike standard light or matter wave Sagnac interferometers no free wave propagation is used. Interferometer operation is controlled only with static, radio-frequency and microwave magnetic fields, which removes the need for interferometric stability of optical laser beams. Due to the confinement of atoms, the scheme may allow the construction of small scale portable sensors. We discuss the main elements of the scheme and report on recent results and efforts towards its experimental realization.