Spectroscopic characterization of the quantum linear-zigzag transition in trapped ions

Ion trap system

The ion trap is a linear radio-frequency (rf) Paul trap¹⁴ consisting of four rods and two endcap needles with an ion-to-rod distance of R = 0.66 mm and two needle endcaps with a tip-to-tip separation of 2.5 mm (Fig. 1a). The trap operates at a radio frequency Ω_rf/2π = 16.9 MHz, rf voltage amplitude V_rf = 770 V, and endcap voltage V_ec = 67 − 155 V depending on ion number. The trap has typical secular frequencies ν_ℓ = ω_ℓ/2π of 864 kHz and 844 kHz along the transverse x and y principal axes and 303 kHz along the axial z axis for five ions…