Laser control of atomic and molecular states has been an important staple of quantum optics and the experimental realization of quantum computing systems. In the present project, we proposed a new tool to broaden the possibilities for precise control of the interaction between ground state atom-pairs and concentrated on a thorough analysis of its usability. The proposed new tool, called Rydberg optical Feshbach-resonance (ROFER), is based on Rydberg molecular states, which is a special bound state of two or three atoms, provided by the Rydberg-excitation of one of the atoms' valence electrons. The essence of the ROFER method is to non-resonantly couple a set (2,3) of ground-state atoms to the Rydberg-molecular state. As a result, the ground-state atoms inherit the binding interaction of the molecule. The interaction engineered among the set of atoms is well controllable: the interaction strength is tunable by the properties of the coupling laser field and the characteristic length scale by changing the principal value of the Rydberg-state used to couple to.
These properties allow the proposed scheme to become an important tool in quantum optics for experiments where the precise control on atom-atom interaction is a requirement. Furthermore, the characteristic length scale of the ROFER methods represents a new regime in optical experiments.
The overall objective of the project was to design and analyze experimentally feasible interaction schemes based on ROFER in various important cases, for example, atoms in continuous space and optical lattices and different atomic species. We also aimed for describing many-body phenomena in atomic ensembles.
The main conclusion of our investigations is that the ROFER method proposed in this project is a useful tool for changing interactions between ground-state atomic pairs in continuous space. The experimental feasibility was not only demonstrated by our theoretical work, but also proved by an experimental group shortly after our proposal. Our calculations also suggest that the technique is well applicable for different species of atoms with one or two valence electrons. in contrast, our analysis for atoms trapped in optical lattices showed that the robustness of the scheme in continuous space is significantly reduced by the confinement of the ground-state atoms.
Regarding the description of many-body phenomena in atomic ensembles, we started a new approach by developing a machine learning algorithm based on Gaussian process regression to describe charge transport in a chain of ground-state atoms and perform extrapolation for a larger number of atoms. Although the results of this part of the project are not yet ready for dissemination, the software package that we developed is a useful basis for further research and it also allowed the researcher to acquire skills to further her carrier as a data scientist.
