Realization of the motion ground state EIT cooling and entanglement between deal-type qubits

• These days, Barium is emerging as a strong candidate for trapped ion systems due to its favorable laser wavelength, potential for high laser intensity, and the availability of metastable qubits in the D5/2 state.
  
  
  
  We initially proposed an efficient method for cooling the phonon motion mode to near zero using Electromagnetically Induced Transparency (EIT) cooling, and we successfully implemented this technique on our ion chain. [1]
  
  
  
  These days, scientists are also paying more attention to dual-type schemes due to their potential to reduce the qubit-switching depth of quantum circuits and facilitate sympathetic cooling. We have identified a clock state on the D5/2 level in an appropriate magnetic field to create a dual-type qubit in the Barium-137 platform. By applying an individual 532 nm laser beam, we successfully implemented a direct MS gate between the dual-type qubit and achieved the same fidelity as the single-type MS gate. [2]
  
  
  
  [1]Chuanxin Huang, et.al Electromagnetically Induced Transparency Cooling of High-Nuclear-Spin Ions PhysRevLett.133(2024).113204
  
  
  
  [2] Chenxi Wang, et.al Experimental Realization of Direct Entangling Gates between Dual-Type Qubits Phys.Rev.Lett. 134 (2025) 1, 010601