Quantum and Gravitational Theory Group

January 17, 2023

January 24, 2023

Title: Quantum dimer models in the age of Rydberg quantum simulators 

Abstract: Strongly interacting arrays of Rydberg atoms provide versatile platforms for exploring exotic many-body phases and dynamics of correlated quantum systems. Motivated by recent experimental advances, we investigate the quantum phases that can be realized by such Rydberg atom simulators in two dimensions. We show that the combination of Rydberg interactions and appropriate lattice geometries naturally leads to constrained dimer models and emergent Z₂ gauge theories endowed with matter fields. Based on this mapping, we demonstrate how Rydberg platforms can be used to realize topological spin liquid states based solely on their native van der Waals interactions. We also discuss the nature of the fractionalized excitations of two distinct classes of such Z₂ quantum spin liquid states and illustrate their rich interplay with proximate solid phases.

*Note: This week the seminar will be held in Abelson 229

January 31, 2023

Title: Maximal Entangling Rates from Holography

Abstract: We prove novel speed limits on the growth of entanglement, equal time correlators, and spacelike Wilson loops in spatially uniform time-evolving states in strongly coupled CFTs with holographic duals. These bounds can also be viewed as quantum weak energy conditions. Several of the speed limits are valid for regions of arbitrary size and with multiple connected components, and our findings imply new bounds on the effective entanglement velocity of small subregions. In 2d CFT, our results prove a conjecture by Liu and Suh for a large class of states. Key to our findings is a momentum-entanglement correspondence, showing that entanglement growth is computed by the momentum crossing the HRT surface. In our setup, we prove a number of general features of boundary-anchored extremal surfaces, such as a sharp bound on the smallest radius that a surface can probe, and that the tips of extremal surfaces cannot lie in trapped regions. Our methods rely on novel global GR techniques, including a delicate interplay between Lorentzian and Riemannian Hawking masses. While our proofs assume the dominant energy condition in the bulk, we provide numerical evidence that our bounds are true under less restrictive assumptions.

*Note: This week the seminar will be held in Abelson 229

February 7, 2023

February 14, 2023

February 21, 2023

February 28, 2023

March 7, 2023

March 14, 2023

March 21, 2023

March 28, 2023

April 4, 2023

April 11, 2023

April 18, 2023

April 25, 2023

May 2, 2023