1. Exploring long range dipolar interactions: from collective dipolar spin dynamics and layer exchange to light-mediated interactions and pauli-blocking

Thomas Bilitewski

Oklahoma State University, USA

17 November 2022 Thu 4 pm

                                      IBS Center for Theoretical Physics of Complex Systems (PCS), Administrative Office (B349), Theory Wing, 3rd floor

                                      Expo-ro 55, Yuseong-gu, Daejeon, South Korea, 34126 Tel: +82-42-878-8633                     

In this talk I will discuss recent theoretical and experimental work exploring the dynamics of dipolar quantum systems for quantum sensing, simulation and discovery.

I will begin by discussing our theoretical proposal using dipolar molecules confined in two dimensions as a platform for robust generation of entangled states, useful for quantum metrology and quantum enhanced field sensing. To this end I will discuss how we can understand the dynamics of the dipolar quantum gas in terms of a long-range highly-collective spin model in mode-space. The highly collective nature of the resulting model allows us to overcome challenges of losses inherent to dipolar molecules in bulk systems, and results in dynamics robust to dephasing and thermal noise in the degenerate quantum degenerate regime. I will then continue by presenting recent experimental work developing the tool box required to prepare and probe molecules in layer geometries, and our theoretical work on understanding the spin dynamics resulting from dipolar exchange. The dipolar interaction induced spin exchange between adjacent layers enables strong inter-layer pair spin-flip creation processes, allowing to probe the coherent exchange process via the measurement of the ensuing molecular loss. I will discuss how in presence of electric field gradients the spin dynamics can only be understood in terms of inelastic collisions between molecules in adjacent layers, converting motional into internal energy during the exchange process. This part highlights how motional dynamics and spin dynamics are intertwined in this system. Finally I will discuss the interplay of light-mediated dipolar interactions, atomic motion and quantum statistics in the problem of observing Pauli-blocking enhanced life-times of optically excited states in a 2D Fermi gas. I will present a theoretical framework developed to account for the main cooperative effects due to the dipolar interactions mediated by the exchange of photons, and the statistics of Fermions enabling us to identify a favourable regime in which Pauli-blocking can be clearly distinguished from cooperative effects, and present experimental observations in qualitative agreement with our theoretical predictions.

References:  PRL 126, 113401 (2021),  Science 375, 1299 - 1303 (2022) , PRL 128, 093001 (2022)