Kritsana Srakaew: Unlocking the potential of Rydberg interactions in quantum systems
The doctoral student explored how long-range interactions shape light-matter coupling and quantum phases.
In his PhD project, Kritsana Srakaew investigated how tunable long-range interactions of Rydberg atoms can be utilised in quantum many-body systems. His research focused on two key settings: subwavelength atomic arrays and itinerant Hubbard systems. His findings deepen our understanding of how Rydberg interactions shape quantum systems, opening new avenues for controlling light-matter interactions and studying complex quantum phases.
Rydberg atoms are known for their highly excited electronic states. Their long-range interactions make them ideal candidates for exploring fundamental quantum phenomena. In his research, Kritsana incorporated these interactions into two-dimensional subwavelength atomic arrays. By employing a single Rydberg atom, he manipulated the strong light-matter interaction of the subwavelength array to render the system either transparent or reflective to probe photons, effectively enabling optical switching. His research revealed that individual atoms and photons can be made to interact in a controlled way, a crucial step toward engineering atom-photon entanglement.
In the second part of his research, Kritsana investigated how these long-range interactions could be integrated into the so-called itinerant one-dimensional Hubbard model that describes moving particles in a one-dimensional system. He used the 'Rydberg dressing’ technique where atoms are weakly coupled to Rydberg states allowing the interaction strength to be precisely tuned. While interactions between Rydberg atoms normally lead to rapid decay, the doctoral student succeeded in extending the lifetime of the interacting atomic ensemble by periodically pulsing the interactions – allowing for a more detailed investigation of the system. The technique enabled him to observe repulsively-bound atomic pairs – atoms that remain paired despite repelling each other – as well as the stabilisation of charge density wave states in out-of-equilibrium dynamics. Additionally, he found that tuning the strength of long-range interactions influenced how the atoms arranged themselves in a nearly stable state, revealing transitions between different ordered phases. These results open up new possibilities for studying complex phase transitions in quantum many-body systems.
Kritsana conducted his PhD research under the supervision of Johannes Zeiher and Immanuel Bloch. “For five years, I had the privilege of working in a highly collaborative and resourceful environment, where state-of-the-art infrastructure and a supportive management team fostered a vibrant research community”, Kritsana explains
What’s next?
Kritsana Srakaew will continue his research as a postdoctoral researcher at the Institute for Molecular Science in Japan. Looking ahead, he remains dedicated to exploring novel quantum phenomena enabled by Rydberg interactions and advancing the frontiers of quantum many-body physics and quantum computing. "My time at MPQ has been incredibly enriching, and I look forward to applying the knowledge and skills I have gained here in my future research endeavours," he says.
