Rydberg-Rydberg interactions and ultracold Rydberg-Rydberg molecules
Final Report Abstract
The DFG-Projekt has explored various aspects of quantum many-body phenomena emerging in a gas of highly excited atoms (Rydberg atoms ). Due to the exaggerated properties of these atomic giants, interactions between individual atoms, which can be of either van-der-Waals or dipolar character, can span macroscopic distances of micrometer size. Four major results were obtained in this project. Firstly, we observed the transformation of the neutral atomic Rydberg gas into an ultracold plasma. Our theoretical analysis of the dynamics revealed the essential processes governing the avalanche-like plasma formation and elucidated the role of initial spatial correlations imposed on the atomic gas through the atomic interactions. Secondly, using the method of Full Counting Statistics usually being applied in condensed matter systems, we could reveal the formation of larger scale, spatially correlated aggregates in the course of the Rydberg excitation process in a gas. In collaboration with colleagues from theoretical physics, we identified the nature of the formation process as a sequential process, in which a first off-resonant Rydberg excitation serves as the nucleation for subsequent excitation of Rydberg atoms as well-dened distances in a given facilitation radius. Our results are of relevance for studies of phase transitions driven by dissipation. Thirdly, we proposed and realized a method to optically image individual Rydberg atoms. The method relies on energy shifts imposed on Rydberg atoms by their mutual interactions, the effect of which are probed by electromagneticaly-induced transparency in a mesoscopic sample of atoms in the ground state (interactionenhanced imaging). Just as an electronic transistor amplifying small electric currents, a single Rydberg atom influences the absorption properties dozens of probe atoms, leading to measurable effect in the optical absorption. In fact, a scheme similar to the one devised by us has recently been used to realize a photon transistor. As the forth major outcome of our research, we have employed our imaging approach to study dipolar energy transport using Rydberg atoms as a model system to reveal essential features of this important phenomenon relevant for, e.g., photosynthesis. This application of our interaction-enhanced imaging method came as a surprise, as we found the original Rydberg excitation to migrate over the ensemble of probe atoms. Theoretical analysis of our observation showed that the diffusive hopping of excitation is governed by an emergent scale, given by the so-called Rydberg blockade, i.e. the blockade of additional Rydberg excitation within a certain volume around an Rydberg atom. INCLUDE SENTENCE ON DISSIPATION ENABLED CREATION OF ENTANGLEMENT OR SO. We could recently show, that the transport in Rydberg gases can serve as a model system to perform quantum simulation of the non-equilibrium dynamics of many-body spin Hamiltonians. Our observations of dipole-mediated transport in a Rydberg gas, which was published in Science accompanied by a News & Views article, has received quite some attention by the general public.
Publications
- Interaction enhanced imaging of individual atoms embedded in dense atomic gases, Phys. Rev. Lett. 108, 013002 (2012)
G. Günter, M. Robert-de-Saint-Vincent, H. Schempp, C. S. Hofmann, S. Whitlock, M. Weidemüller
- Observing the Dynamics of Dipole-Mediated Energy Transport by Interaction-Enhanced Imaging, Science 342, 954-956 (2013)
G. Günter, H. Schempp, M. Robert-de-Saint-Vincent, V. Gavryusev, S. Helmrich, C.S. Hofmann, S. Whitlock, M. Weidemüller
(See online at https://doi.org/10.1126/science.1244843) - Spontaneous avalanche ionization of a strongly blockaded Rydberg gas, Phys. Rev. Lett. 110, 045004 (2013)
M. Robert-de-Saint-Vincent, C. S. Hofmann, H. Schempp, G. Günter, S. Whitlock, M. Weidemüller
(See online at https://doi.org/10.1103/PhysRevLett.110.045004) - Sub-Poissonian Statistics of Rydberg-Interacting Dark-State Polaritons, Phys. Rev. Lett. 110, 203601 (2013)
C. S. Hofmann, G. Günter, H. Schempp, M. Robert-de-Saint-Vincent, M. Gärttner, J. Evers, S. Whitlock, M. Weidemüller
(See online at https://doi.org/10.1103/PhysRevLett.110.203601) - An experimental approach for investigating many-body phenomena in Rydberg-interacting quantum systems, Frontiers of Physics 9, 571-586 (2014)
C. S. Hofmann, G. Günter, H. Schempp, N. M. L. Müller, A. Faber, H. Busche, M. Robert-de-Saint- Vincent, S. Whitlock, M. Weidemüller
(See online at https://doi.org/10.1007/s11467-013-0396-7) - Full Counting Statistics of Laser Excited Rydberg Aggregates in a One-Dimensional Geometry, Phys. Rev. Lett. 112, 013002 (2014)
H. Schempp, G. Günter, M. Robert-de-Saint-Vincent, C. S. Hofmann, D. Breyel, A. Komnik, D. W. Schönleber, M. Gärttner, J. Evers, S. Whitlock, M. Weidemüller
(See online at https://doi.org/10.1103/PhysRevLett.112.013002)
