Atom Interferometry with ultracold Rubidium atoms

Abstract

Atom interferometry, a technique that leverages the wave nature of atoms to create interference patterns, has emerged as a powerful tool for high-precision measurements. This method exploits the principles of quantum mechanics, particularly the wave-particle duality, to achieve remarkable sensitivity and accuracy. Atom interferometers utilise coherent matter waves, typically of ultra-cold atoms, which are manipulated using laser pulses to form superposition states that interfere. The resulting interference patterns provide insights into various physical phenomena, making atom interferometers highly effective in precision metrology, fundamental physics, and practical applications. The development of quantum sensors based on atom interferometry has opened new frontiers in measurement science. Quantum sensors exploit quantum coherence and entanglement to surpass the limitations of classical sensors, offering unprecedented precision. In the realm of inertial sensing, atom interferometers can measure accelerations and rotations with extraordinary accuracy, leading to advances in navigation systems, geophysics, and seismology. For instance, gravimeters based on atom interferometry can detect minute changes in gravitational acceleration, useful for mineral exploration, monitoring volcanic activity, and detecting underground structures. In addition to inertial sensing, atom interferometry is pivotal in testing fundamental physics. It allows precise measurements of constants such as the fine-structure constant and the gravitational constant. Moreover, atom interferometers are instrumental in experiments probing the equivalence principle, a cornerstone of general relativity, and in searches for dark matter and gravitational waves. The sensitivity of these interferometers to tiny perturbations makes them ideal for detecting phenomena predicted by theories beyond the Standard Model of particle physics. The engineering of quantum sensors using atom interferometry involves several critical technologies. These include techniques for cooling and trapping atoms, precise control of laser fields, and advanced methods for isolating the system from environmental noise. Innovations in these areas have led to the development of portable and even chip-scale atom interferometers, broadening their applicability in various fields. Despite significant progress, challenges remain in the practical deployment of atom interferometer-based quantum sensors. These include enhancing the coherence time of atomic superposition states, improving robustness against environmental disturbances, and miniaturizing the systems for real-world applications. Ongoing research focuses on overcoming these challenges through novel quantum control techniques, improved atom optics, and integration with microfabricated technologies. This work explores the development of atomic sensor technology through several key areas. It begins with a detailed examination of atom interferometers, focusing on the interaction between light and atoms in two-level and three-level systems, and the principles of Bragg and Raman diffraction. The research then describes the design and assembly of an experimental setup capable of producing an ensemble of ultracold atoms at a temperature of 100 nK. This setup includes a Bragg lattice used to develop an atom interferometer for ultracold 87-Rb atoms. Subsequent analysis covers Bragg diffraction and atom interferometry, providing insights into the diffraction process within the experimental setup and its influence on atom transitions between momentum states. This section also includes a demonstration of a Mach-Zehnder interferometer utilizing Bragg diffraction. The implementation of the atom interferometer is investigated as an atomic gravimeter, with a new approach proposed to reduce phase noise and improve measurement accuracy and precision. Lastly, the work examines double Bragg diffraction and its potential applications, proposing a new concept for an atom-based Sagnac interferometer to advance the field of atomic sensors.