The ability to control and tune interactions in ultracold atomic gases has paved the way for the realization of new phases of matter. So far, experiments have achieved a high degree of control over short-range interactions, but the realization of long-range interactions has become a central focus of research because it would open up a new realm of many-body physics. Rydberg atoms are highly suited to this goal because the van der Waals forces between them are many orders of magnitude larger than those between ground-state atoms1. Consequently, mere laser excitation of ultracold gases can cause strongly correlated many-body states to emerge directly when atoms are transferred to Rydberg states. A key example is a quantum crystal composed of coherent superpositions of different, spatially ordered configurations of collective excitations2,3,4,5. Here we use high-resolution, in situ Rydberg atom imaging to measure directly strong correlations in a laser-excited, two-dimensional atomic Mott insulator6. The observations reveal the emergence of spatially ordered excitation patterns with random orientation, but well-defined geometry, in the high-density components of the prepared many-body state. Together with a time-resolved analysis, this supports the description of the system in terms of a correlated quantum state of collective excitations delocalized throughout the gas. Our experiment demonstrates the potential of Rydberg gases to realize exotic phases of matter, thereby laying the basis for quantum simulations of quantum magnets with long-range interactions.
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Saffman, M., Walker, T. & Mølmer, K. Quantum information with Rydberg atoms. Rev. Mod. Phys. 82, 2313–2363 (2010)
Weimer, H., Löw, R., Pfau, T. & Büchler, H. P. Quantum critical behavior in strongly interacting Rydberg gases. Phys. Rev. Lett. 101, 250601 (2008)
Pohl, T., Demler, E. & Lukin, M. D. Dynamical crystallization in the dipole blockade of ultracold atoms. Phys. Rev. Lett. 104, 043002 (2010)
Schachenmayer, J., Lesanovsky, I., Micheli, A. & Daley, A. J. Dynamical crystal creation with polar molecules or Rydberg atoms in optical lattices. N. J. Phys. 12, 103044 (2010)
Gärttner, M., Heeg, K. P., Gasenzer, T. & Evers, J. Dynamical formation of floating Rydberg excitation crystals. Preprint at http://arXiv.org/abs/1203.2884v2 (2012)
Bloch, I., Dalibard, J. & Zwerger, W. Many-body physics with ultracold gases. Rev. Mod. Phys. 80, 885–964 (2008)
Jaksch, D., Cirac, J. I., Zoller, P., Côté, R. & Lukin, M. D. Fast quantum gates for neutral atoms. Phys. Rev. Lett. 85, 2208–2211 (2000)
Lukin, M. et al. Dipole blockade and quantum information processing in mesoscopic atomic ensembles. Phys. Rev. Lett. 87, 037901 (2001)
Pupillo, G., Micheli, A., Boninsegni, M., Lesanovsky, I. & Zoller, P. Strongly correlated gases of Rydberg-dressed atoms: quantum and classical dynamics. Phys. Rev. Lett. 104, 223002 (2010)
Henkel, N., Nath, R. & Pohl, T. Three-dimensional roton excitations and supersolid formation in Rydberg-excited Bose-Einstein condensates. Phys. Rev. Lett. 104, 195302 (2010)
Cinti, F. et al. Supersolid droplet crystal in a dipole-blockaded gas. Phys. Rev. Lett. 105, 135301 (2010)
Honer, J., Weimer, H., Pfau, T. & Büchler, H. Collective many-body interaction in Rydberg dressed atoms. Phys. Rev. Lett. 105, 160404 (2010)
Robicheaux, F. & Hernández, J. Many-body wave function in a dipole blockade configuration. Phys. Rev. A 72, 063403 (2005)
van Bijnen, R. M. W., Smit, S., van Leeuwen, K. H., Vredenbregt, E. J. D. & Kokkelmans, S. J. J. M. F. Adiabatic formation of Rydberg crystals with chirped laser pulses. J. Phys. B 44, 184008 (2011)
Lesanovsky, I. Many-body spin interactions and the ground state of a dense Rydberg lattice gas. Phys. Rev. Lett. 106, 025301 (2011)
Höning, M., Muth, D., Petrosyan, D. & Fleischhauer, M. Steady-state crystallization of Rydberg excitations in an optically driven lattice gas. Preprint at http://arXiv.org/abs/1208.2911 (2012)
Tong, D. et al. Local blockade of Rydberg excitation in an ultracold gas. Phys. Rev. Lett. 93, 063001 (2004)
Urban, E. et al. Observation of Rydberg blockade between two atoms. Nature Phys. 5, 110–114 (2009)
Gaëtan, A. et al. Observation of collective excitation of two individual atoms in the Rydberg blockade regime. Nature Phys. 5, 115–118 (2009)
Schwarzkopf, A., Sapiro, R. & Raithel, G. Imaging spatial correlations of Rydberg excitations in cold atom clouds. Phys. Rev. Lett. 107, 103001 (2011)
Dudin, Y. O. & Kuzmich, A. Strongly interacting Rydberg excitations of a cold atomic gas. Science 336, 887–889 (2012)
Wilk, T. et al. Entanglement of two individual neutral atoms using Rydberg blockade. Phys. Rev. Lett. 104, 010502 (2010)
Isenhower, L. et al. Demonstration of a neutral atom controlled-NOT quantum gate. Phys. Rev. Lett. 104, 010503 (2010)
Raitzsch, U. et al. Echo experiments in a strongly interacting Rydberg gas. Phys. Rev. Lett. 100, 013002 (2008)
Reetz-Lamour, M., Amthor, T., Deiglmayr, J. & Weidemüller, M. Rabi oscillations and excitation trapping in the coherent excitation of a mesoscopic frozen Rydberg gas. Phys. Rev. Lett. 100, 253001 (2008)
Dudin, Y. O., Li, L., Bariani, F. & Kuzmich, A. Observation of coherent many-body Rabi oscillations. Nature Phys. http://dx.doi.org/10.1038/nphys2413 (published online, 9 September 2012)
Löw, R. et al. Universal scaling in a strongly interacting Rydberg gas. Phys. Rev. A 80, 033422 (2009)
Viteau, M. et al. Rydberg excitations in Bose-Einstein condensates in quasi-one-dimensional potentials and optical lattices. Phys. Rev. Lett. 107, 060402 (2011)
Olmos, B., Li, W., Hofferberth, S. & Lesanovsky, I. Amplifying single impurities immersed in a gas of ultracold atoms. Phys. Rev. A 84, 041607(R) (2011)
Günter, G. et al. Interaction enhanced imaging of individual Rydberg atoms in dense gases. Phys. Rev. Lett. 108, 013002 (2012)
Endres, M. et al. Observation of correlated particle-hole pairs and string order in low-dimensional Mott insulators. Science 334, 200–203 (2011)
Müller, M., Lesanovsky, I., Weimer, H., Büchler, H. P. & Zoller, P. Mesoscopic Rydberg gate based on electromagnetically induced transparency. Phys. Rev. Lett. 102, 170502 (2009)
Weimer, H., Müller, M., Lesanovsky, I., Zoller, P. & Büchler, H. P. A Rydberg quantum simulator. Nature Phys. 6, 382–388 (2010)
We thank R. Löw for discussions. We acknowledge funding by MPG, DFG, EU (NAMEQUAM, AQUTE, Marie Curie Fellowship to M.C.) and JSPS (Postdoctoral Fellowship for Research Abroad to T.F.).
The authors declare no competing financial interests.
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Schauß, P., Cheneau, M., Endres, M. et al. Observation of spatially ordered structures in a two-dimensional Rydberg gas. Nature 491, 87–91 (2012). https://doi.org/10.1038/nature11596
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