Ph.D. Candidate: Gregory Scott Bentsen
Research Advisor: Monika Schleier-Smith
Date: Monday, August 5, 2019
Location: PAB 102/103
Title: Nonlocal Light-Mediated Interactions for Fast Scrambling
Quantum entanglement is essential to the description of diverse physical phenomena occurring in condensed matter, cold atomic, high-energy, and gravitational systems. The Fast Scrambling Conjecture places a fundamental bound on the growth rate of many-body entanglement in arbitrary quantum systems. Quantum systems that saturate this bound, such as black holes, are called Fast Scramblers and generate entanglement at the fastest rate possible; such systems may be regarded as nature's fastest information processors. Can such an ultimate processor be built in the laboratory? In this public defense I present minimal ingredients for experimental access to fast scrambling dynamics and present concrete, realistic proposals for engineering fast scramblers in the laboratory using nonlocal cavity-mediated interactions available in near-term cavity QED experiments. The high degree of tunability of these optically-controlled interactions enables experimental simulation of entirely novel classes of exotic nonlocal spin models with unconventional properties. Theoretical analysis of these spin models reveals a rich set of many-body phenomena, including a novel form of integrability in one family of spin models and the emergence of treelike geometries in another. I report on experimental demonstrations paving the way toward simulating these spin models, including the first direct imaging of nonlocal spin-exchange dynamics. Finally, I present the first experimental proposals for measuring Out-of-Time-Ordered Correlators to diagnose quantum information scrambling in experimental systems; these proposals have since been realized in the laboratory by several experimental groups. These building blocks lay the groundwork for experimental access to fast scrambling and the controlled production of increasingly complex forms of entanglement, which we expect to continue to play a key role in our understanding of problems arising in fields ranging from quantum information processing to condensed matter to quantum gravity.