Article
Extended Data Fig. 1 | Conceptual view of the arrangement used for
high-resolution spectroscopy of HD+ using TICTES. The spectroscopy wave
(1.3 THz) crosses the ion cluster perpendicular to its long axis, enabling
spectroscopy in the Lamb–Dicke regime. The ion cluster comprises atomic Be+
ions (blue dots) and HD+ molecular ions (red dots). The indicated laser beams
implement the Doppler cooling of Be+ ions (313 nm), rotational cooling of HD+
(2.7 μm and 5.48 μm) and detection by REMPD (266 nm and 1.4 μm). The
magnetic field B lifts the degeneracy of Zeeman sublevels during terahertz
spectroscopy. The polarizer and the half-wave plate enable adjustment of the
polarization and intensity of the terahertz radiation.