Monopoles Constructed by Cold Atoms

Edwin Norbeck

Zixian Zhou, Zhi-Guo Lü, Hang Zheng

We construct an artificial U(1) gauge field in the cold atom system to form a monopole along with vortices. It is supposed that the cold atoms are confined on a spherical surface, and two sets of identical laser beams in the opposite propagating directions shine on two sides of the sphere. Arbitrary Chern number CN, proportional to the quantized magnetic flux, can be obtained by selecting proper laser modes. This construction meets the condition of Chern's theorem, so that the vortices of the atom wave function will emerge on the sphere, whose winding number equals CN. It is found that a geometric symmetry is broken spontaneously for odd CN, which corresponds to a topology-induced quantum phase transition. In particular for CN=1, the ground state of the cold atoms are double-degenerate and can be applied to make a stable qubit. Since the ground-state degeneracy is protected by topology-induced symmetry breaking against dissipation, the proposed topological structure has vast potential in quantum storage.

Jelena Stajic

Quantum Simulation Topological properties of physical systems are reflected in so-called Chern numbers: A nonzero Chern number typically means that a system is topologically nontrivial. Sugawa et al. engineered a cold atom system with a nonzero second Chern number, in contrast to condensed matter physics, where only the first Chern number is usually invoked. The exotic topology relates to the emergence of a type of magnetic monopole called the Yang monopole (known from theoretical high-energy physics) in a five-dimensional space of internal degrees of freedom in a rubidium Bose-Einstein condensate. The results illustrate the potential of cold atoms physics to simulate high-energy phenomena. Science , this issue p. [1429][1] [1]: /lookup/doi/10.1126/science.aam9031

W. E. Baylis

J. Denschlag

Yuxin Hu, Christian Miniatura, David Wilkowski +1 more

We propose to generate an artificial non-Abelian U(3) gauge field by using a two-tripod scheme, namely, two tripod configurations sharing a common ground-state level and driven by resonant one-photon transitions. Using an appropriate combination of four Laguerre-Gauss and two Hermite-Gauss laser beams, we are able to produce a U(3) monopole and a U(3) spin-orbit coupling for both alkali-metal and alkaline-earth-metal atoms. This two-tripod scheme could open the way to the study of interacting spinor condensates subjected to U(3) monopoles.