Neutral atomic Bose condensates and degenerate Fermi gases have been used to realize important many-body phenomena in their most simple and essential forms1,2,3, without many of the complexities usually associated with material systems. However, the charge neutrality of these systems presents an apparent limitation—a wide range of intriguing phenomena arise from the Lorentz force for charged particles in a magnetic field, such as the fractional quantum Hall effect in two-dimensional electron systems4,5. The limitation can be circumvented by exploiting the equivalence of the Lorentz force and the Coriolis force to create synthetic magnetic fields in rotating neutral systems. This was demonstrated by the appearance of quantized vortices in pioneering experiments6,7,8,9 on rotating quantum gases, a hallmark of superfluids or superconductors in a magnetic field. However, because of technical issues limiting the maximum rotation velocity, the metastable nature of the rotating state and the difficulty of applying stable rotating optical lattices, rotational approaches are not able to reach the large fields required for quantum Hall physics10,11,12. Here we experimentally realize an optically synthesized magnetic field for ultracold neutral atoms, which is evident from the appearance of vortices in our Bose–Einstein condensate. Our approach uses a spatially dependent optical coupling between internal states of the atoms, yielding a Berry’s phase13 sufficient to create large synthetic magnetic fields, and is not subject to the limitations of rotating systems. With a suitable lattice configuration, it should be possible to reach the quantum Hall regime, potentially enabling studies of topological quantum computation.
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We thank W. D. Phillips for discussions. This work was partially supported by ONR, ARO with funds from the DARPA OLE programme, and the NSF through the JQI Physics Frontier Center. R.L.C. acknowledges the NIST/NRC postdoctoral programme and K.J.-G. thanks CONACYT.
Author Contributions All authors contributed to writing of the manuscript. Y.-J.L. led the data collection effort (with assistance from R.L.C. and K.J.-G.). I.B.S. and J.V.P. designed the original apparatus, which was largely constructed by I.B.S., and Y.-J.L. implemented the specific changes required for the present experiment. I.B.S. conceived the experiment and performed numerical and analytic calculations. This work was supervised by I.B.S. with consultations from J.V.P.
About this article
International Journal of Theoretical Physics (2018)