RUI: Demonstrating Control Over State-Mixing Interactions in Rydberg Excitation Near Förster Resonance

Kenyon College, Gambier OH

Investigators

Abstract

The field of quantum information is poised to revolutionize computation, data security, and our understanding of fundamental science. In quantum computers, individual units of information, or bits, are stored in single quantum objects. Atoms are often used because they are electrically neutral and interact very weakly, so fragile quantum states can remain undisturbed. However, to use atoms to do a computation, they must be made to interact at the right time, and in the right way. The key to solving this problem is the Rydberg excitation blockade, which results when atoms are cooled to extremely low temperatures, and the outermost electrons are excited to very large orbits. These highly excited atoms interact, and the interactions can lead to a suppression of excitation into high-lying states. This “blocking” of excitation has led to many important breakthroughs in the pursuit of neutral atom quantum technologies. In this project, the PI and coworkers will study a process that makes the blockade break down: state-mixing interactions. When one tries to excite atoms to a particular Rydberg state near an interaction resonance, the atoms can be mixed into other, unwanted states with high probability. This grant will focus on developing tools to control these state-mixing interactions, so their effect on the blockade can be minimized. The PI and co-PI will also develop a research-based training program for the lead tutors at Kenyon’s Math and Science Skills Center. The training will focus on using metacognition, or thinking about one’s own cognitive processes, when the tutors interact with students. The PIs hope to increase students’ sense of self-efficacy in STEM courses, and enhance persistence rates across STEM disciplines at Kenyon College. The Rydberg excitation blockade, or the suppression of laser excitation due to strong interactions, is the key to using neutral atoms to implement quantum information protocols. State-mixing interactions, which result from couplings among multi-particle Rydberg states near Förster resonance, can compromise this suppression under otherwise favorable conditions. In recent work, the PI and his students showed that the mechanism that causes large rates of state mixing depends sensitively on experimental conditions. In the present project they will exploit this sensitivity to develop a broad toolbox for control over state-mixing interactions. This toolbox includes pulse duration, Rabi frequency, atom separation, principal quantum number, and applied electric field. They will compare their measurements with different theoretical models, characterized by either two or three interacting particles. Finally, they will design a training program in metacognition for lead tutors at Kenyon’s Math and Science Skills Center, as a way to encourage cognitively efficient, but correct reasoning. They will use research-validated instruments to measure changes in students’ self-efficacy. Improved self-efficacy has been linked to a broad range of positive outcomes, including persistence in STEM. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.