Double-EIT Ground-State Cooling of Stationary Two-Dimensional Ion Lattices

We theoretically and experimentally study the electromagnetically-induced-transparency (EIT) cooling of two-dimensional ion lattices in a Paul trap. We realize the EIT ground-state cooling with ¹⁷¹Yb⁺ ions with hyperfine-energy levels different from other ions with a simple Λ-scheme that has already been used. We observe a cooling rate n ˙ = 3 ×10⁴ quanta/s and a cooling limit n = 0 . 06 +/- 0 . 059 for a single ion. The measured cooling rate and limit are consistent with theoretical predictions. We apply the double-EIT cooling on two-dimensional (2D) lattices with up to 12 ions and observe an average phonon number n = 0 . 54 +/- 0 . 12 for the center of mass mode. Different from the 2D crystal in the Penning trap, cooling rates of multiple ions are similar to that of a single ion. The ground-state cooling of a 2D lattice with a large number of ¹⁷¹Yb⁺ ions will advance the field of the quantum simulation of 2D systems. Our method can be also extended to the other hyperfine qubits.

This work was supported by the National Key Research and Development Program of China under Grants No. 2016YFA0301900 and No. 2016YFA0301901 and the National Natural Science Foundation of China Grants No. 11374178, No. 11574002, and No. 11974200.