Theory seminar: Universal spin transport and microscopic control of cooperative optical response in atomic arrays

Johannes Zeiher (MPQ Bloch division)
Universality is one of the guiding principles to unify the description of disparate physical phenomena.

Johannes Zeiher (MPQ Bloch division)
Group seminar (hybrid format: B0.32/zoom)
Wed, 9. February 2022, 10:30 am (MEZ)

Abstract:

Universality is one of the guiding principles to unify the description of disparate physical phenomena. Kardar-Parisi-Zhang (KPZ) universality is one celebrated example and known for describing various instances of interface growth. Surprisingly, KPZ was recently also conjectured to arise in spin-transport in Heisenberg quantum magnets near equilibrium and at infinite temperature. I will describe our experiments to probe this conjecture in a quantum gas microscope in chains of up to 50 spins. With our measurements, we corroborate the central aspects of the conjecture by demonstrating superdiffusive transport, sensitivity to symmetry and integrability as well as a skewed distribution of the transported spin. The second part of the talk will be dedicated to cooperative atomic response to light fields. Realizing an ordered atomic array in an optical lattice, we first observe subradiant optical response of a cooperative mirror. Employing strong dipolar Rydberg interactions, we then controllably switch the optical properties of the entire array with a locally addressed single ancilla atom. Driving Rabi oscillations on the ancilla, we demonstrate coherent control of transmission and reflection of the mirror. Our results pave the way towards the realization of novel quantum metasurfaces and the creation of controlled atom-photon entanglement.