TY - JOUR T1 - Reply to Comment on "Space-Time Crystals of Trapped Ions Y1 - 2012 A1 - Tongcang Li A1 - Zhe-Xuan Gong A1 - Zhang-qi Yin A1 - H. T. Quan A1 - Xiaobo Yin A1 - Peng Zhang A1 - L. -M. Duan A1 - Xiang Zhang AB - This is a reply to the comment from Patrick Bruno (arXiv:1211.4792) on our paper (Phys. Rev. Lett. 109, 163001 (2012)). UR - http://arxiv.org/abs/1212.6959v2 U5 - http://dx.doi.org/10.1103/PhysRevLett.109.163001 ER - TY - JOUR T1 - Space-Time Crystals of Trapped Ions JF - Physical Review Letters Y1 - 2012 A1 - Tongcang Li A1 - Gong, Zhe-Xuan A1 - Yin, Zhang-Qi A1 - Quan, H. T. A1 - Yin, Xiaobo A1 - Zhang, Peng A1 - Duan, L.-M. A1 - Zhang, Xiang AB - Spontaneous symmetry breaking can lead to the formation of time crystals, as well as spatial crystals. Here we propose a space-time crystal of trapped ions and a method to realize it experimentally by confining ions in a ring-shaped trapping potential with a static magnetic field. The ions spontaneously form a spatial ring crystal due to Coulomb repulsion. This ion crystal can rotate persistently at the lowest quantum energy state in magnetic fields with fractional fluxes. The persistent rotation of trapped ions produces the temporal order, leading to the formation of a space-time crystal. We show that these space-time crystals are robust for direct experimental observation. We also study the effects of finite temperatures on the persistent rotation. The proposed space-time crystals of trapped ions provide a new dimension for exploring many-body physics and emerging properties of matter. VL - 109 U4 - 163001 UR - http://link.aps.org/doi/10.1103/PhysRevLett.109.163001 CP - 16 U5 - 10.1103/PhysRevLett.109.163001 ER -