Project Details
Projekt
Infinite-range interactions in atomic spin systems
Applicant
Professor Dr. József Fortágh
Subject Area
Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
Theoretical Condensed Matter Physics
Theoretical Condensed Matter Physics
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 465199066
The goal of our project is to realize scalable all-to-all interactions between distant Rydberg atoms mediated by a superconducting microwave resonator. In the first funding period, we conducted experiments with ultracold rubidium Rydberg atoms in the mode volume of a superconducting coplanar microwave resonator at cryogenic temperature of 4 K, with the aim of demonstrating strong atom-cavity coupling and cavity-mediated atom-atom interactions. Thereby we encountered significant challenges due to inhomogeneity of the cavity field, as well as inhomogeneous electrostatic fields originating from surface-adsorbed charges and dipoles that led to strong spatial variation of Rydberg energies of the atoms positioned near the chip surface. We have developed methods to suppress the surface field effects to some extent and to control Rydberg excitations in their presence. In spite of extensive efforts, we have not achieved coupling between Rydberg atom pairs. We conclude that the planar microwave resonator geometry imposes limitations, and that a non-planar design would be advantageous in mitigating field inhomogeneities. We have started developing a new flipped-chip resonator architecture, based on a lumped-element resonator connected to a pair of capacitors with spatial separation of 200 𝜇m. In between the capacitor plates, trapped Rydberg atoms interact with the microwave field of the cavity. We plan to use this three-dimensional cavity design as the experimental platform in the upcoming funding period in order to achieve microwave cavity-mediated interactions between two or more Rydberg atoms. In the following funding period, our focus will be on establishing stable Rydberg state control in a three-dimensional flipped-chip cavity. We will implement schemes for coherent interactions between distant Rydberg atoms, mediated by the microwave field of the cavity in a thermal state. Our objective is to determine the optimal parameters for achieving robust, coherent coupling. Finally, we aim to scale up the number of interacting Rydberg atoms to realize all-to-all interactions over long distances. This will enable the exploration of complex quantum systems with tunable interactions, laying the groundwork for implementing exchange Hamiltonians, Ising models, and multi-qubit quantum gates.
DFG Programme
Research Units
