We provide an analytical description of the dynamics of an atom in an optical lattice using the method of perturbative adiabatic expansion. A precise understanding of the lattice-atom interaction is essential to taking full advantage of the promising applications that optical lattices offer in the field of atom interferometry. One such application is the implementation of large momentum transfer (LMT) beam splitters that can potentially provide multiple order of magnitude increases in momentum space separations over current technology. We also propose interferometer geometries where optical lattices are used as waveguides for the atoms throughout the duration of the interferometer sequence. Such a technique could simultaneously provide a multiple order of magnitude increase in sensitivity and a multiple order of magnitude decrease in interferometer size for many applications as compared to current state-of-the-art atom interferometers.
We provide an analytical description of the dynamics of an atom in an optical lattice using the method of perturbative adiabatic expansion. A precise understanding of the lattice-atom interaction is essential to taking full advantage of the promising applications that optical lattices offer in the field of atom interferometry. One such application is the implementation of large momentum transfer (LMT) beam splitters that can potentially provide multiple order of magnitude increases in momentum space separations over current technology. We also propose interferometer geometries where optical lattices are used as waveguides for the atoms throughout the duration of the interferometer sequence. Such a technique could simultaneously provide a multiple order of magnitude increase in sensitivity and a multiple order of magnitude decrease in interferometer size for many applications as compared to current state-of-the-art atom interferometers.
Since the first demonstrations in 1991, atom interferometry has been a burgeoning field of research. The work done in this field is motivated by the potential sensitivity improvements that atom-based devices can have over the current state-of-the-art light- and MEMS-based devices. This dissertation presents a new and unique approach to atom interferometry in that we perform the basic interferometric sequence of splitting, propagation, reflection, reverse-propagation, and recombination with atoms trapped in a phase-modulated (shaken) optical lattice. In both simulation and experiment we demonstrate a one-dimensional shaken lattice interferometer configured as an accelerometer. The interferometry sequence is developed through the use of learning and optimal control algorithms that allow us to implement the desired state-to-state transformations and perform the desired operations, e.g. splitting and recombination of the atoms trapped in the lattice. This device has a sensitivity that scales as the square of the interrogation time and an ability to distinguish both the magnitude and sign of an applied acceleration signal. Furthermore we show that we can tailor the transfer function of the interferometer to be sensitive to a signal of interest, e.g. an AC signal of a given frequency. Finally, we explore the analytics of shaken lattice interferometry and offer some suggestions as to the future of this new technology.
The goal of this thesis is to study a novel approach towards all-optical continuous waveguide interferometers based on quasi-Bragg waveguide beam splitters. The Bragg beam splitter for matter waves is comprised of a periodic lattice produced by partial or full interference between two Gaussian laser beams and are used as waveguides for ultra-cold atoms. In the experimental conditions, where both waveguides have wide and deep potentials, atoms are unable to split from a single lattice. Instead, several spatially separated regions of the optical lattice are required, fulfilling the Bragg condition. This thesis will present clear evidence of the detection of discrete quantised momentum states of the atoms, created from a process of ultra-cold atoms undergoing interference in the single arms of a Michelson interferometer. A detailed investigation of the different regimes of the splitter has been completed by varying the initial atom velocity and the amplitude of the optical lattice. The findings from the study have produced optimal parameters where the splitting ratio of the atoms between the two waveguides can be finely controlled by the amplitude of the lattice within certain limits. A Michelson interferometer configuration is used to test the coherence of the atoms by decelerating them after splitting in the lattice. The return velocity of atoms is set to be equal to the initial velocity and the two clouds are recombined using the original lattice. A sinusoidal oscillation of the atomic momentum between the two output ports of the beam splitter is visible. However, only interference in single Michelson interferometer arms has been observed. The reasons are discussed in detail along with plans to move towards an all-optical design.
We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beam splitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such as low power beam splitters (<100 μW), large momentum transfer beam splitters with modest power, or new self-aligned interferometer geometries utilizing the transverse modes of the optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with >75% contrast and measure the acceleration due to gravity, g, to 60 μg/sqrt[Hz] resolution in a Mach-Zehnder geometry. We use >10(7) cesium atoms in the compact mode volume (600 μm 1/e(2) waist) of the cavity and show trapping of atoms in higher transverse modes. This work paves the way toward compact, high sensitivity, multiaxis interferometry.
Large-momentum-transfer techniques are instrumental for the next generation of atom interferometers as they significantly improve their sensitivity. State-of-the-art implementations rely on elastic scattering processes from optical lattices such as Bloch oscillations or sequential Bragg diffraction, but their performance is constrained by imperfect pulse efficiencies. Here we develop a Floquet-based theoretical framework that provides a unified description of elastic light-atom scattering across all relevant regimes. Within this formalism, we identify practical regimes that exhibit orders of magnitude reduced losses and improved phase accuracy compared to previous implementations. The model's validity is established through direct comparison with numerical solutions of the Schrödinger equation and through quantitative agreement with recent experimental benchmark results. These findings delineate previously unexplored operating regimes for large momentum transfer beam splitters and open new perspectives for precision atom-interferometric measurements in fundamental physics, gravity gradiometry or gravitational wave detection.
We demonstrate atom interferometers utilizing a novel beam splitter based on sequential multiphoton Bragg diffractions. With this sequential Bragg large momentum transfer (SB-LMT) beam splitter, we achieve high contrast atom interferometers with momentum splittings of up to 102 photon recoil momenta (102ℏk). To our knowledge, this is the highest momentum splitting achieved in any atom interferometer, advancing the state-of-the-art by an order of magnitude. We also demonstrate strong noise correlation between two simultaneous SB-LMT interferometers, which alleviates the need for ultralow noise lasers and ultrastable inertial environments in some future applications. Our method is intrinsically scalable and can be used to dramatically increase the sensitivity of atom interferometers in a wide range of applications, including inertial sensing, measuring the fine structure constant, and detecting gravitational waves.
The development of atom interferometry in the last few decades has led to high precision measurements of inertial effects and tests of fundamental physics. New methods for higher sensitivity atom interferometers (AIs) are being explored, particularly the interrogation of atoms with optical cavities [1]. Its benefits would be higher optical power allowing large momentum transfer beam splitters, and possibly cleaner and controlled phase profiles. However high sensitivity AIs require long interrogation times, which combined with cold atom expansion, bring the challenges of large waists in cavities.