Strongly-correlated Rydberg quantum gases

Ultracold atomic gases are ideally suited for exploring the quantum physics of many-body systems and for investigating quantum matter and exotic quantum phenomena. We make use of the extraordinary properties of highly-excited Rydberg atoms in dense atomic gases to explore the realm of strongly-correlated many-body physics.

Ultracold Rydberg gases

[Image: New Rydberg detector at the Universitaet Heidelberg.]

Photo of the new Rydberg detector. The detector allows for precise control over electric fields to manipulate Rydberg atoms and incorporates two ionization detectors for detecting individual atoms.

For more than a century, atoms excited to high lying Rydberg states have been subject to research in many different fields because of their unique quantum mechanical properties. For example, due to their large polarizabilities, Rydberg atoms are extremely sensitive to external fields and can interact very strongly, even over macroscopic distances. By combining laser cooling and trapping of atoms with the coherent excitation of Rydberg atoms from dense atomic gases we are entering a new era of Rydberg physics. Of particular interest, the typical interaction ranges between Rydberg atoms are comparable to, or larger than, the typical interatomic separations in a Bose-Einstein condensate (BEC), which creates new possibilities to control atomic interactions in quantum gases and can lead to new strongly-correlated phases of matter.

A long standing focus of the Quantum Dynamics group has been on coherent excitation of Rydberg atoms, and the dramatic effects caused by strong Rydberg-Rydberg interactions. See for example our recent results on interaction induced imaging of single atoms and coherent population trapping involving excited Rydberg states.

We have built a new experiment, aimed at studying ultracold Rydberg atoms in dense atomic gases. Our new system possesses excellent optical access for creating optical dipole traps and optical lattices, combined with great control over electric fields necessary for the study of strongly interacting Rydberg atoms. Key aspects include all-optical evaporation, a compact two-dimensional MOT (2DMOT) as a cold atom source, and a new single atom sensitive Rydberg detector, which includes sensitive ion detectors and a system of 8 individually addressable electrodes capable of generating virtually any electric field configuration. With this new system we will have complete access to the microscopic properties of interacting Rydberg systems, allowing for new studies of novel quantum phases, collective properties and entanglement in complex many-body systems.

Latest news and research results

Download the latest poster from the Rydberg group [pdf]

Review of the EU Training Network on Rydberg physics published as a special issue of the EPJ04.01.2017
Juris

The recently published special issue of the European Physical Journal (EPJ) reviews achievements of the EU Integrated Training Network on Rydberg Physics. The training network, which is going under the abbreviation COHERENCE and was funded from 2012 to 2015 by the European Commission, was devoted to promote young researchers in the field of Rydberg gases. The central research topic was the investigation of interactions among highly excited (Rydberg) atoms under extremely controlled conditions. This kind of research has many applications in fundamental science and technology at the crossroads between atomic, molecular and condensed matter physics, quantum optics, quantum simulation, and others. Our research group, representing Heidelberg University, was one of the leading teams among 18 European and US universities and research institutions that were involved in the network. During the project more than 100 articles in high-impact journals were published. This special issue summarizes the major scientific results of COHERENCE in a series of 15 review-style articles.

For more information:
Read the complete special issue here (open access!): Cooperativity and Control in Highly Excited Rydberg Ensembles - Achievements of the European Marie Curie ITN COHERENCE
Contribution from our group: Gavryusev et al., Interaction Enhanced Imaging of Rydberg P states, Eur. Phys. J. Spec. Top. 225, 2863 (2016)


Interaction Enhanced Imaging of Rydberg P states published in Eur. Phys. J. Special Topics!19.12.2016
Vladislav Gavryusev

The Interaction Enhanced Imaging technique allows to detect the spatial distribution of strongly interacting impurities embedded within a gas of background atoms used as a contrast medium. Here we present a detailed study of this technique, applied to detect Rydberg P states.

We experimentally realize fast and efficient threephoton excitation of P states, optimized according to the results of a theoretical effective two-level model. Few Rydberg P-state atoms, prepared in a small cloud with dimensions comparable to the blockade radius, are detected with a good sensitivity by averaging over 50 shots. The main aspects of the technique are described with a hard sphere model, finding good agreement with experimental data. This work paves the way to a non-destructive optical detection of single Rydberg atoms with high spatial and temporal resolution.

Reference:
V. Gavryusev et al., Interaction Enhanced Imaging of Rydberg P states: Preparation and detection of Rydberg atoms for engineering long-range interactions, Eur. Phys. J. Special Topics 225, 2863–2889 (2016), or see our full list of publications
Vladislav Gavryusev is now Dr. V. Gavryusev!19.12.2016
Vladislav Gavryusev

Vladislav Gavryusev from the Rydberg team successfully defended his thesis... Congratulations!

Afterwards he received his PhD hat (see picture). The hat came with a replica of one of the lasers used in the Rydberg experiment. Vladislav had to lock the laser to a little cavity and align it to the center of a mini-vacuum chamber (which was actually at room pressure...). Afterwards Vlad had to proof his german and dancing skills. In the end he mastered all the tasks his hat had to offer and now truly deserves his PhD!

Reference:
V. Gavryusev, Imaging of Rydberg Impurities in an Ultracold Atomic Gas, PhD thesis, or see our full list of publications

Publications by the Rydberg project

2016 Nobuyuki Takei, Christian Sommer, Claudiu Genes, Guido Pupillo, Haruka Goto, Kuniaki Koyasu, Hisashi Chiba, Matthias Weidemüller, Kenji Ohmori, Direct observation of ultrafast many-body electron dynamics in an ultracold Rydberg gas, Nature Comm. 7, 13449 (2016)

V. Gavryusev, A. Signoles, M. Ferreira-Cao, G. Zürn, C. S. Hofmann, G. Günter, H. Schempp, M. Robert-de-Saint-Vincent, S. Whitlock, M. Weidemüller, Density matrix reconstruction of three-level atoms via Rydberg electromagnetically induced transparency, Journal of Physics B: Atomic, Molecular and Optical Physics 49, 164002 (2016) [pdf]

V. Gavryusev, M. Ferreira-Cao, A. Kekic, G. Zürn, A. Signoles, Interaction Enhanced Imaging of Rydberg P states, The European Physical Journal Special Topics 225, 2863-2889 (2016) [pdf]

2015 H. Schempp, G. Günter, S. Wüster, M. Weidemüller, S. Whitlock, Correlated Exciton Transport in Rydberg-Dressed-Atom Spin Chains, Phys. Rev. Lett. 115, 093002 (2015) [pdf]

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, Full Counting Statistics of Laser Excited Rydberg Aggregates in a One-Dimensional Geometry, Phys. Rev. Lett. 112, 013002 (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, An experimental approach for investigating many-body phenomena in Rydberg-interacting quantum systems, Frontiers of Physics 9, 571-586 (2014)

2013 G. Günter, H. Schempp, M. Robert-de-Saint-Vincent, V. Gavryusev, S. Helmrich, C.S. Hofmann, S. Whitlock, M. Weidemüller, Observing the Dynamics of Dipole-Mediated Energy Transport by Interaction-Enhanced Imaging, Science 342, 954-956 (2013)

M. Robert-de-Saint-Vincent, C. S. Hofmann, H. Schempp, G. Günter, S. Whitlock, M. Weidemüller, Spontaneous avalanche ionization of a strongly blockaded Rydberg gas, Phys. Rev. Lett. 110, 045004 (2013) [pdf]

Matthias Weidemüller, Atomic Interactions at a Distance, Physics 6, 71 (2013) [pdf]

Matthias Weidemüller, Quantum physics: Spooky action gets collective, Nature 498, 438 (2013)

C. S. Hofmann, G. Günter, H. Schempp, M. Robert-de-Saint-Vincent, M. Gärttner, J. Evers, S. Whitlock, M. Weidemüller, Sub-Poissonian Statistics of Rydberg-Interacting Dark-State Polaritons, Phys. Rev. Lett. 110, 203601 (2013) [pdf]

2012 G. Günter, M. Robert-de-Saint-Vincent, H. Schempp, C. S. Hofmann, S. Whitlock, M. Weidemüller, Interaction enhanced imaging of individual atoms embedded in dense atomic gases, Phys. Rev. Lett 108, 013002 (2012) [pdf]

2011 S Sevincli, C Ates, T Pohl, H Schempp, C S Hofmann, G Günter, T Amthor, M Weidemüller, J D Pritchard, D Maxwell, A Gauguet, K J Weatherill, M P A Jones, C S Adams, Quantum interference in interacting three-level Rydberg gases: coherent population trapping and electromagnetically induced transparency, J. Phys. B: At. Mol. Opt. Phys. 44, 184018 (2011) [pdf]

T. Amthor, C. Hofmann, J. Knorz, M. Weidemüller, High-precision semiconductor wavelength sensor based on a double-layer photo diode, Review of Scientific Instruments 82, 093111 (2011)

2010 H. Schempp, G. Günter, C.S. Hofmann, C. Giese, S.D. Saliba, B. D. DePaola, T. Amthor, M. Weidemüller, S. Sevinçli, T. Pohl, Coherent population trapping with controlled interparticle interactions, Phys. Rev. Lett. 104, 173602 (2010)

Thomas Amthor, Christian Giese, Christoph S. Hofmann, Matthias Weidemüller, Evidence of Antiblockade in an Ultracold Rydberg Gas, Phys. Rev. Lett. 104, 013001 (2010)

2009 M. Weidemüller, Rydberg atoms - There can be only one, Nature Physics 5 (2009)

T. Amthor, J. Denskat, C. Giese, N. N. Bezuglov, A. Ekers, L. Cederbaum, M. Weidemüller, Autoionization of an ultracold Rydberg gas through resonant dipole coupling, Eur. Phys. J. D 53, 329 (2009)

T. Amthor, M. Reetz-Lamour, M. Weidemüller, Frozen Rydberg Gases, in: Cold Atoms and Molecules, Wiley VCH (2009)

2008 M. Reetz-Lamour, J. Deiglmayr, T. Amthor, M. Weidemüller, Rabi oscillations between ground and Rydberg states and van der Waals blockade in a mesoscopic frozen Rydberg gas, New J. Phys. 10, 045026 (2008)

2007 M. Reetz-Lamour, T. Amthor, S. Westermann, J. Denskat, A. L. de Oliveira, M. Weidemüller, Modeling few-body phenomena in an ultracold Rydberg gas, Nucl. Phys. A 790, 728c (2007)

Thomas Amthor, Markus Reetz-Lamour, Sebastian Westermann, Janne Denskat, Matthias Weidemüller, Mechanical effect of van der Waals interactions observed in real time in an ultracold Rydberg gas, Phys. Rev. Lett. 98, 023004 (2007)

2006 Johannes Deiglmayr, Markus Reetz-Lamour, Thomas Amthor, Sebastian Westermann, André Luiz de Oliveira, Matthias Weidemüller, Coherent excitation of Rydberg atoms in an ultracold gas, Opt. Comm. 264, 293 (2006)

Markus Reetz-Lamour, Thomas Amthor, Johannes Deiglmayr, Sebastian Westermann, Kilian Singer, André Luiz de Oliveira, Luis Gustavo Marcassa, Matthias Weidemüller, Prospects of ultracold Rydberg gases for quantum information processing, Fortschr. Phys. 54, 776 (2006)

V. A. Nascimento, M. Reetz-Lamour, L. L. Caliri, A. L. de Oliveira, L. G. Marcassa, Motion in an ultralong-range potential in cold-Rydberg-atom collisions, Phys. Rev. A 73, 034703 (2006)

2005 K. Singer, J. Stajonevic, M. Weidemüller, R. Côté, Long-range interactions between alkali Rydberg atom pairs correlated to the ns-ns, np-np and nd-nd asymptotes, J. Phys. B 38, S295 (2005)

K. Singer, M. Reetz-Lamour, T. Amthor, S. Fölling, M. Tscherneck, M. Weidemüller, Spectroscopy of an ultracold Rydberg gas and signatures of Rydberg-Rydberg interactions, J. Phys. B 38, S321 (2005)

M. Weidemüller, K. Singer, M. Reetz-Lamour, T. Amthor, L.G. Marcassa, Ultralong-Range Interactions and Blockade of Excitation in a Cold Rydberg Gas, in: Atomic Physics XIX, pp. 157-163 (2005)

M. Weidemüller, M. Reetz-Lamour, T. Amthor, J. Deiglmayr, K. Singer, L.G. Marcassa, Interactions in an Ultracold Gas of Rydberg Atoms, in: Laser Spectroscopy XVII, pp. 264-274 (2005)

2004 K. Singer, M. Reetz-Lamour, T. Amthor, L. G. Marcassa, M. Weidemüller, Spectral Broadening and Suppression of Excitation Induced by Ultralong-Range Interactions in a Cold Gas of Rydberg Atoms, Phys. Rev. Lett. 93, 163001 (2004)