Extended Data Fig. 4: Optical coherence of Er3+:CaWO4.
From: Indistinguishable telecom band photons from a single Er ion in the solid state
a Timing sequence for an optical Hahn echo experiment. The ion is initialized into \(\left|{\uparrow }_{g}\right\rangle \) state using 10 pairs of optical πB and microwave πMWe pulses. b An optical Hahn echo measurement (green) reveals an optical coherence of T2,o = 10.2 μs. Applying XY32 dynamical decoupling sequence (orange) extends the optical coherence to the radiative limit (blue dashed line) T2,o = 18 μs, at a field where the optical T1,o = 9.1(3) μs. c Timing sequence for an optical XYN experiment. d Dephasing rate scaling with the number of refocusing pulses of XY dynamical decoupling sequences (red) compared to the lifetime limit (blue).
