Dissertation

New Directions in Quantum Simulation and Metrology via Contact and Photon-Mediated Interactions

Chu, Anjun

2024

Overview

Highly controllable atomic, molecular, and optical systems have emerged as an increasingly powerful toolkit in advancing the frontiers of quantum simulation, metrology, computation, and fundamental physics. In this thesis, we present theoretical work on manipulation of contact and photon-mediated interactions in optical lattice clocks and cavity QED systems, as well as explorations of their possible applications on problems relevant for quantum simulation and metrology.We start from an overview of the relevant theoretical background for this thesis, including optical lattices, contact interactions, spin systems, photon-mediated interactions and measurements, as well as metrological concepts. We then present research in three closely related directions.Firstly, we discuss theory ideas for optimizing the performance of optical lattice clocks via Hamiltonian engineering. Based on the tunable delocalization of Wannier-Stark states in tilted lattices, we can fine-tune the relative strength of on-site p-wave and nearest-neighbor s-wave interactions, leading to a minimization of density shifts in a 1D optical lattice clock. We also discuss the tunability of nearest-neighbor interactions by lattice geometry. Considering the improved sensitivity of optical lattice clocks, we further analyze the manifestation of general relativistic effects in a quantum many-body optical lattice clock and discuss protocols for their near-term observation.Additionally, we discuss theory ideas for exploring emergent collective behaviors and dynamical phases in interacting arrays. We utilize sideband transitions in trapped bosonic gases to engineer Lipkin-Meshkov-Glick model and identify dynamical phase transitions between ferromagnetic and paramagnetic phases. We also provide a theoretical proposal for correlated hopping processes facilitated by multilevel atoms in cavity QED systems, which features intriguing phenomena such as chiral transport and correlation spreading behaviors. We then consider protocols for the control and amplification of atomic Bloch oscillations via cavity-mediated interactions. Moreover, we realize the Bardeen–Cooper–Schrieffer (BCS) model, an iconic model that describes the behavior of superfluids and superconductors, by photon-mediated spin exchange interactions using the Anderson pseudospin mapping, and for the first time observe a dynamical phase with persistent oscillations of the BCS order parameter.Finally, we discuss theory ideas for entanglement generation via photon-mediated interactions and measurements. We provide a theory proposal for implementing homogeneous one-axis twisting interactions in a lattice-based atom interferometer using partial delocalized Wannier-Stark states in tilted lattices, which suppresses inhomogeneities in atom-light couplings at a magic lattice depth. We also compare two common approaches experimentally used to generate spin squeezing in cavity QED systems, quantum nondemolition measurements and unitary one-axis twisting dynamics. We derived simple criteria to determine the best protocol based on the detector's quantum efficiency.

• Publisher: ProQuest Dissertations & Theses
• Subject: Atomic physics / Condensed matter physics / Physics / Quantum physics
• ISBN: 9798384052067