Long-range interactions and many-body effects in a cold Rydberg gas

Matthias Weidemüller, Kilian Talo Theodor Singer, M. Reetz‐Lamour +2 more

Jianing Han, Tom Gallagher

Jun Zhang, En-Ze Li, Yajun Wang +15 more

The interplay between strong long-range interactions and the coherent driving contribute to the formation of complex patterns, symmetry, and novel phases of matter in many-body systems. However, long-range interactions may induce an additional dissipation channel, resulting in non-Hermitian many-body dynamics and the emergence of exceptional points in spectrum. Here, we report experimental observation of interaction-induced exceptional points in cold Rydberg atomic gases, revealing the breaking of charge-conjugation parity symmetry. By measuring the transmission spectrum under increasing and decreasing probe intensity, the interaction-induced hysteresis trajectories are observed, which give rise to non-Hermitian dynamics. We record the area enclosed by hysteresis loops and investigate the dynamics of hysteresis loops. The reported exceptional points and hysteresis trajectories in cold Rydberg atomic gases provide valuable insights into the underlying non-Hermitian physics in many-body systems, allowing us to study the interplay between long-range interactions and non-Hermiticity. Long-range interactions in many-body quantum systems may induce dissipation channels described by non-Hermitian dynamics. Here, the authors report the observation of higher-order exceptional points, a hallmark of non-Hermitian physics, in a Rydberg atom gas. This enables design of quantum dynamics around these points, providing insight into phase transitions.

Jovica Stanojevic, Robin C ot 'e

Yaroslav O. Dudin, A. Kuzmich

Highly excited Rydberg atoms have many exaggerated properties. In particular, the interaction strength between such atoms can be varied over an enormous range. In a mesoscopic ensemble, such strong, long-range interactions can be used for fast preparation of desired many-particle states. We generated Rydberg excitations in an ultra-cold atomic gas and subsequently converted them into light. As the principal quantum number n was increased beyond ~70, no more than a single excitation was retrieved from the entire mesoscopic ensemble of atoms. These results hold promise for studies of dynamics and disorder in many-body systems with tunable interactions and for scalable quantum information networks.

Riccardo Faoro, Bruno Pelle, Alexandre Zuliani