Fig. 2: Pulse sequences.
From: Improved bounds on Lorentz violation from composite pulse Ramsey spectroscopy in a trapped ion
a The applied composite rf pulse sequence is a more robust version of a spin-echoed Ramsey scheme. A Ramsey sequence of Trf = 1236.27 ms starts and ends with a π/2-pulse. A 2.15 ms-long modulation sequence of 10 π-pulses with phases ϕi (i = 1. . . 10), each spaced by 2tw = 200 μs, is repeated N = 575 times to cancel dephasing due to ambient magnetic field noise. The phases ϕi are chosen such (see text) that the sequence is robust against pulse errors. b Every n = 50 measurements, a 4-point servo sequence (E3 servo) of 40 s is applied to follow the E3 center frequency, after which the rf sequence is compiled for 2.5 s. The measurement sequence consists of two 50 ms-long E3 pulses (E3), the rf pulse sequence (rf) of 1236.27 ms, four detection pulses (D) of 2.5 ms and a sequence at the end of 20 ms for state preparation (R) for the next measurement run. During post-selection, the data points are considered valid if the ion was in the desired state during the first three detection pulses.
