Probing Non-Equilibrium Dynamics in Two-Dimensional Quantum Gases

This thesis explores the physics of non-equilibrium quantum dynamics in homogeneous two-dimensional (2D) quantum gases. It produces ultracold cesium atoms in a quasi-2D optical box potential and develops a high-resolution, in situ imaging technique to monitor the evolution of collective excitations and quantum transport. It also uses tunable Feshbach resonances to control interactions with high temporal and spatial resolutions and performs interaction quenches to control the generation and evolution of quasiparticles in quantum gases, presenting the first direct measurement of quantum entanglement between interaction quench generated quasiparticle pairs in an atomic superfluid.

Format: Hardback
Length: 148 pages
Publication date: 12 October 2022
Publisher: Springer International Publishing AG

This thesis delves into the realm of non-equilibrium quantum dynamics in homogeneous two-dimensional (2D) quantum gases, a field that has gained significant attention due to the study of quantum many-body physics in ultracold quantum gases driven out of equilibrium. However, probing non-equilibrium dynamics in conventionally trapped, inhomogeneous atomic quantum gases has posed significant challenges due to the coexistence of mass transport and spreading of quantum correlations, complicating experimental analyses. In this groundbreaking work, the author overcomes this technical hurdle by producing ultracold cesium atoms in a quasi-2D optical box potential. The exquisite optical trap enables the removal of density inhomogeneity in a degenerate quantum gas, allowing for precise control of its dimensionality. Furthermore, the author develops a high-resolution, in situ imaging technique to monitor the evolution of collective excitations and quantum transport down to atomic shot-noise, at the length scale of elementary collective excitations.

Additionally, tunable Feshbach resonances in ultracold cesium atoms enable precise and dynamical control of interactions with high temporal and even spatial resolutions. By employing these state-of-the-art techniques, the author conducts interaction quenches to manipulate the generation and evolution of quasiparticles in quantum gases, presenting the first direct measurement of quantum entanglement between interaction quench-generated quasiparticle pairs in an atomic superfluid. Quenching to attractive interactions, this work demonstrates stimulated emission of quasiparticles, leading to amplified density waves and fragmentation, forming 2D matter-wave Townes solitons that were previously deemed impossible to form in equilibrium due to their instability. This thesis unveils a set of scale-invariant and universal phenomena that govern the non-equilibrium dynamics of atomic quantum gases, shedding light on the complex interplay between quantum coherence, collective excitations, and interactions.

The study of non-equilibrium quantum dynamics in homogeneous two-dimensional (2D) quantum gases has emerged as a crucial field in the realm of quantum many-body physics. Ultracold quantum gases, driven out of equilibrium, have provided a prominent platform for exploring the complex behavior of quantum systems. However, the investigation of non-equilibrium dynamics in conventionally trapped, inhomogeneous atomic quantum gases has posed significant challenges due to the coexistence of mass transport and spreading of quantum correlations. In this thesis, the author aims to address this technical hurdle by producing ultracold cesium atoms in a quasi-2D optical box potential.

The optical trap employed in this work allows for the removal of density inhomogeneity in a degenerate quantum gas, enabling precise control of its dimensionality. Moreover, the author develops a high-resolution, in situ imaging technique to monitor the evolution of collective excitations and quantum transport down to atomic shot-noise, at the length scale of elementary collective excitations. This technique provides a powerful tool for studying the intricate dynamics of atomic quantum gases.

Furthermore, the author explores the use of tunable Feshbach resonances in ultracold cesium atoms to control interactions with high temporal and even spatial resolutions. These resonances enable precise manipulation of the interaction strength between atoms, allowing for the study of complex phenomena such as quantum chaos and the emergence of novel phases of matter.

In this thesis, the author conducts interaction quenches to control the generation and evolution of quasiparticles in quantum gases. By quenching to attractive interactions, the author demonstrates stimulated emission of quasiparticles, leading to amplified density waves and fragmentation. This work presents the first direct measurement of quantum entanglement between interaction quench-generated quasiparticle pairs in an atomic superfluid.

The study of non-equilibrium quantum dynamics in homogeneous two-dimensional (2D) quantum gases has opened up new avenues for exploring the complex behavior of quantum systems. The techniques developed in this thesis, such as ultracold atom production, high-resolution imaging, and tunable Feshbach resonances, have enabled researchers to study the generation and evolution of quasiparticles in atomic quantum gases with unprecedented precision. The results obtained in this thesis have significant implications for the field of quantum information science and may lead to the development of new technologies for quantum computing and communication.

Weight: 418g
Dimension: 235 x 155 (mm)
ISBN-13: 9783031133541
Edition number: 1st ed. 2022