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.

Far from equilibrium dynamics of a Rydberg spin system

The dynamics of strongly-interacting quantum systems constitutes one of the most challenging problems in modern science, touching basic concepts of statistical physics, thermodynamics and quantum physics. These systems are particularly intriguing since disorder gives rise to a variety of collective phenomena like anomalously slow dynamics, the breakdown of thermalization and the emergence of novel glassy phases of matter. As a model system we use a frozen gas of Rydberg atoms where the spin is encoded in two electronically excited states. This system is ideally suited for exploring the dynamics of isolated quantum systems due to the huge dipolar interaction between Rydberg atoms. Using coherent laser beams and arbitrary pulse sequences of microwave radiation, we experimentally implement novel tools for quantum engineering and diagnostics.

Transport of Rydberg excitations

We study the transport of Rydberg excitations in a cold atomic cloud. A single excitation to an impurity Rydberg state couples via resonant dipole-dipole interactions to the background atoms, which are dressed with another Rydberg state via electromagnetically induced transparency. The transparent background is therefore rendered absorptive around the impurity. This allows direct optical detection of transport dynamics. The imaging process presents a tunable degree of decoherence, which enables the study of different transport regimes.

Nonlinear photon interactions in a Rydberg-EIT medium

Making photons interact lies at the heart of modern quantum optics and has applications for example in all-optical quantum information processing. Coupling light to an interacting gas of Rydberg atoms under conditions of electromagnetically induced transparency (EIT) provides a strong optical nonlinearity, which allows for photonic interactions on the single photon level. This rapidly evolving field of Rydberg-EIT paves the way for applications such as photon transistors and fosters investigations of many-body physics with interacting photons as well as exotic states of light.
Our group recently predicted a two-body, two-photon resonance that enhances the optical nonlinearity in the regime of low optical depth per blockade radius and allows to alter the absorptive and dispersive properties of the Rydberg gas.

Engineering Rydberg-spin hamiltonians

Rydberg atoms constitute an ideal platform to perform quantum simulations of Heisenberg-spin systems. By mapping the spin degree of freedom to two atomic states, involving at least one high-lying Rydberg state, Ising-, XX- and XXZ-models can be realized. Depending on the specific form of the underlying Hamiltonian, interesting phases of matter can be observed that are yet not fully understood.
However, Rydberg quantum simulators (as well as simulators on other platforms) are usually only suited to study a specific class of Hamiltonians and it is often quite demanding or even impossible to change the implemented Hamiltonian in a controlled way.
One approach to overcome this fundamental limitation is to engineer terms in a given interaction Hamiltonian by means of global control pulses. Traditionally, these techniques have been developed in nuclear magnetic resonance (NMR) in order to filter interactions and single particle dephasing. Nowadays, the use of pulse sequences have been extended to not only cancel terms, but to modify them in a desired way. Our goal is to study relaxation dynamics in a disordered spin system under general XYZ- Hamiltonians using microwave pulse sequences.

Latest news and research results

Download the latest poster from the Rydberg group [pdf]

Nonlinear optical response in Rydberg-EIT medium: paper published in Phys. Rev. A 06.12.2019
Annika Tebben

This month, our paper on a "Blockade-induced resonant enhancement of the optical nonlinearity in a Rydberg medium" got published in Phys. Rev. A! We predict the enhancement of the nonlinear optical response of the Rydberg gas as a consequence of a two-photon process that resonantly couples electronic states of a pair of atoms dressed by a strong control field. Moreover, we propose a realistic experimental scenario to observe the resonance by performing transmission measurements

A. Tebben et al., Blockade-induced resonant enhancement of the optical nonlinearity in a Rydberg medium, Phys. Rev. A 100, 063812, (2019), or see our full list of publications
Dr. Clément Hainaut is now an Alexander von Humboldt Fellow 28.02.2019
Annika Tebben

Congratulations to Clément Hainaut who was awarded an Alexander von Humboldt Fellowship! Clément joined the Rydberg team as a postdoc for investigating relaxation dynamics of Rydberg spin systems as well as nonlinear photon interactions in a Rydberg EIT medium!

Annika Tebben receives Otto-Haxel-Prize for her Master thesis 27.10.2018
Annika Tebben

During her Master thesis Annika Tebben investigated the nonlinear optical response of an interacting Rydberg gas under conditions of electromagnetically induced transparency. In collaboration with the group of Thomas Pohl (Aarhus) she found a method to resonantly enhance the associated nonlinear susceptibility. For her outstanding work Annika was awarded the Otto-Haxel-Prize of the department of physics and astronomy of Heidelberg University. Congratulations!

Publications by the Rydberg project

2020Charles Möhl, Nicholas L.R. Spong, Yuechun Jiao, Chloe So, Teodora Ilieva, Matthias Weidemüller, Charles S. Adams, Photon correlation transients in a weakly blockaded Rydberg ensemble, J. Phys. B: At. Mol. Opt. Phys. 53, 084004 (2020)

Miguel Ferreira Cao, Vladislav Gavryusev, Titus Franz, Renato Ferracini Alves, Adrien Signoles, Gerhard Zürn, Matthias Weidemüller, Depletion imaging of Rydberg atoms in cold atomic gases, J. Phys. B: At. Mol. Opt. Phys. 53, 084005 (2020)

A. Signoles, T. Franz, R. Ferracini Alves, M. Gärttner, S. Whitlock, G. Zürn, M. Weidemüller, Observation of glassy dynamics in a disordered quantum spin system, Phys. Rev. X, in press (arXiv:1909.11959) (2020)

2019 Tebben, Annika, Hainaut, Clément, Walther, Valentin, Zhang, Yong-Chang, Zürn, Gerhard, Pohl, Thomas, Weidemüller, Matthias, Blockade-induced resonant enhancement of the optical nonlinearity in a Rydberg medium, Phys. Rev. A 100, 063812 (2019)

S. Whitlock, H. Wildhagen, H. Weimer, M. Weidemüller, Diffusive to non-ergodic dipolar transport in a dissipative atomic medium, Phys. Rev. Lett. 123, 213606 (2019)

2018 Orioli, A. Pineiro, Signoles, A., Wildhagen, H., Günter, G., Berges, J., Whitlock, S., Weidemüller, M., Relaxation of an Isolated Dipolar-Interacting Rydberg Quantum Spin System, Phys. Rev. Lett. 120, 063601 (2018)

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. a Günter, S. Whitlock, M. Weidemüller, Spontaneous avalanche ionization of a strongly blockaded Rydberg a 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. a Hofmann, S. Whitlock, M. Weidemüller, Interaction enhanced imaging of individual atoms embedded in dense a atomic gases, Phys. Rev. Lett 108, 013002 (2012) [pdf]

2011 S Sevincli, C Ates, T Pohl, H Schempp, C S Hofmann, a G Günter, T Amthor, M Weidemüller, J D Pritchard a, D Maxwell, A Gauguet, K J Weatherill, M P A Jones, a C S Adams, Quantum interference in interacting three-level Rydberg gases: coherent a 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 a photo diode, Review of Scientific Instruments 82, 093111 (2011)

2010 H. Schempp, G. Günter, C.S. Hofmann, C. Giese, S.D. a Saliba, B. D. DePaola, T. Amthor, M. Weidemüller, a 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 a 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 a, L. Cederbaum, M. Weidemüller, Autoionization of an ultracold Rydberg gas through resonant dipole a 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 a blockade in a mesoscopic frozen Rydberg gas, New J. Phys. 10, 045026 (2008)

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

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

Markus Reetz-Lamour, Thomas Amthor, Johannes Deiglmayr, a Sebastian Westermann, Kilian Singer, André Luiz de Oliveira a, 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 a 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 a 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, a M. Tscherneck, M. Weidemüller, Spectroscopy of an ultracold Rydberg gas and signatures of Rydberg-Rydberg a interactions, J. Phys. B 38, S321 (2005)

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

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