Abstract

The Yb⁺ ion is known to have (i) a ground- state hyperfine resonance (¹⁷¹Yb^{+ 2}S₁/₂ F= 0↔1) that is precisely detectable by microwave-optical double resonance (Fig. 1 ), and (ii) at least two di pole-forbidden lines (E2 ²S₁/₂ → ²D₅/₂ - 1/2 822nm, and E3 ²S₁/₂ —> ²F₇/₂ - 467nm) suitable for the control of a diode-laser-based optical frequency standard [1-3]. We have prepared a single ¹⁷¹Yb⁺ ion in a Paul trap, cooled it down to the Lamb-Dicke regime by irradiation with 369-nm frequency-doubled light of a cw dye laser and detected its resonance scattering. Optical pumping into the ²D₃/₂ level was undone by simultaneous excitation with either 2.4-μm light of a colour centre laser [3] or with a 609-nm dye-laser light. Microwave π/2 pulse pairs ( 12.6 GHz, separation τ), sandwiched between the pulses of the resonance light and their frequency being stepped across the hyperfine resonance m_p = 0 → 0, generated Ramsey fringes. The observed minimum width of a fringe is 12 Hz (τ = 40ms), Fig. 2.

© 1996 Optical Society of America