Ultracold atoms in periodically modulated optical potentials: A quantum metamaterial to explore nonequilibrium dynamics and tosimulate relativistic effect

• Applicants: Professor Sergey Denisov, Ph.D.; Professor Dr. Martin Weitz
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 231556095

• Final Report Year: 2018

Final Report Abstract

We demonstrated that, by using periodic modulations and the technique of Fourier synthesis of optical potentials, a plethora of new effects characteristic to quantum nonequilibrium and relativistic physics can be explored. With a dilute atomic rubidium Bose-Einstein condensate in a variable optical lattice potential, the phenomenon of relativistic Veselago lensing was experimentally demonstrated for the first time in matter waves. In other work with the cold atom system, a topologically protected edge state between two regions of different topological order was spatially resolved. In the course of the project, we also realized, with ultracold rubidium atoms in a timemodulated optical lattice potential, a quantum rocking ratchet. Both the existence and the possibility to control quantum Floquet resonances could be experimentally demonstrated. The presence of these resonances in the transport characteristics of ac-driven quantum ratchets, as well as a universal bifurcation scenario they undergo upon increase of the modulation amplitude, were predicted by the Augsburg team in a theoretical paper. We found very good agreement of our experimental results with the predictions of the theoretical model. Tuneable band structures of optical potentials and the possibility to create a quasi-cone dispersion with a controllable gap, by bringing low energy bands into avoiding crossing, potentially allows to realize another paradigmatic model, the quantum Rabi Hamiltonian. We demonstrated (so far in theory) that, by changing the quasi-momentum of the atoms, the system can be tuned into the deep strong coupling regime, an issue hardly attainable with other systems.

Publications

• Vesleago lensing with ultracold atoms in an optical lattice, Nature Comm. 5, 3327 (2014)
  M. Leder, C. Grossert, and M. Weitz
  
• Experimental control of transport resonances in a coherent quantum rocking ratchet, Nature Comm. 7, 10440 (2016)
  C. Grossert, M. Leder, S. Denisov, P. Hänggi, and M. Weitz
  
• Phase dependent loading of Bloch bands and quantum simulation of relativistic wave equation predictions with ultracold atoms in variably shaped optical lattice potentials, J. Mod. Opt. 63, 1805 (2016)
  C. Grossert, M. Leder, and M. Weitz
  
• Real-space imaging of a topological protected edge state with ultracold atoms in an amplitudechirped optical lattice, Nature Comm. 7, 13112 (2016)
  M. Leder, C. Grossert, L. Sitta, M. Genske, A. Rosch, and M. Weitz
  
• Asymptotic Floquet states of open quantum systems: The role of interactions, New J. Phys. 19, 083011 (2017)
  M. Hartmann, D. Poletti, M. Ivanchenko, S. Denisov, P. Hänggi
  
• Quantum Rabi model in the Brillouin zone with ultracold atoms, Phys. Rev. A 95, 013827(2017)
  S. Felicetti, E. Rico, C. Sabin, T. Ockenfels, J. Koch, M. Leder, C. Grossert, M. Weitz, and E. Solano
  
• Quantum resonant activation, Phys. Rev. E 95, 042104 (2017)
  L. Magazzu, P. Hänggi, B. Spagnolo, and D. Valenti
  
• Role of work in matter exchange between finite quantum systems, New J. Phys. 19, 093006 (2017)
  E. Jeon, P. Talkner, J. Yi, Y. K. Kim