Fig. 4: Entanglement fidelity degradation due to atomic motion.
From: High-fidelity remote entanglement of trapped atoms mediated by time-bin photons
As the time-bin period τ is tuned away from being commensurate with trapped ion motion (in all three directions of motion for both ions), entanglement fidelity decreases. As predicted in Eq. (4), the loss of fidelity due to asynchronous timing depends on the thermal occupation number of each of the six modes of motion, with the value τ = 6048 ns nearly eliminating this error (see Table 1). Points are measured fidelity values from parity scans, and the dashed line represents a rescaled version of Eq. (4) ("Doppler fit" in the above plot). We note this data run was not optimized to give the best fidelities and is separate from the main result we present in this paper. The solid lines show the theoretical fidelity limitation from motion with our system’s beam geometry ("Doppler unoptimized") and with optimal Doppler cooling geometry ("Doppler optimized") [see Supplementary Information]. The blue solid line ("ZPC") is for zero-point cooling.
