Liu, Shuwei2025-07-102025-07-102025-07-102025-07-02https://hdl.handle.net/10012/21990This thesis explores how quantum information behaves in extreme physical settings, from black hole interiors to noisy quantum devices. First, we derive a thermodynamic relation linking gravitational shockwaves to microscopic deformations of the black hole horizon, illuminating the connection between quantum chaos and horizon area deformation. Next, we explore the black hole information problem through the lens of holography, demonstrating how scrambling and recoverability emerge from gravitational backreaction in shockwave geometries. Finally, we shift to quantum technologies, introducing noise-strength-adapted (NSA) quantum error-correcting codes discovered via hybrid machine learning. These non-stabilizer codes outperform conventional designs under amplitude damping and generalize to larger systems. Together, these works reveal how quantum information unifies seemingly disparate domains, offering both conceptual insights into spacetime and practical tools for building resilient quantum systems.enDoctoral Thesis