I will present recent results of our group in the rapidly developing field of synthetic magnetic fields for atoms and photons, in cold atomic gases and photonic structures, respectively. The results can be categorized in three closely related groups.
(i) It will be shown that a Hamiltonian with Weyl points can be realized for ultracold atoms using laser-assisted tunneling in three-dimensional optical lattices [1]. Weyl points are synthetic magnetic monopoles that exhibit a robust, three-dimensional linear dispersion, identical to the energy-momentum relation for relativistic Weyl fermions, which are not yet discovered in particle physics. Weyl semimetals are a promising new avenue in condensed matter physics due to their unusual properties such as 'Fermi arc' surface states. However, experiments on Weyl points are highly elusive. We show that this elusive goal is well-within experimental reach with an extension of techniques recently used in ultracold gases.
(ii) We present a grating assisted tunneling scheme for tunable synthetic magnetic fields in photonic lattices. The synthetic fields emerge from the nontrivial phases of the resulting tunneling matrix elements. We propose implementation of the Harper-Hofstadter Hamiltonian in these photonic lattices, and demonstrate its realization by using the so-colled conical diffraction [2].
(iii) Finally, we present a novel theoretical proposal [3], and the experimental demonstration [4], of synthetic magnetic fields that were for the first time achieved in classical cold atomic gases. The scheme utilizes radiation pressure forces and the Doppler effect. The experiment was implemented in the 87Rb Magneto-Optical Trap [4].


REFERENCES
1. Tena Dubcek, Colin J. Kennedy, Ling Lu, Wolfgang Ketterle, Marin Soljacic, Hrvoje Buljan, Weyl points in three-dimensional optical lattices: Synthetic magnetic monopoles in momentum space, Phys. Rev. Lett. 114, 225301 (2015).
2. Tena Dubcek, et al., submitted
3. T. Dubcek, N. Santic, D. Jukic, D. Aumiler, T. Ban, and H. Buljan, Synthetic Lorentz force in classical atomic gases via Doppler effect and radiation pressure, Phys. Rev. A 89, 063415 (2014).
4. Neven Santic, Tena Dubcek, Damir Aumiler, Hrvoje Buljan, Ticijana Ban, Experimental Demonstration of a Synthetic Lorentz Force by Using Radiation Pressure, Scientific Reports 5, 13485 (2015).