Fig. 3: Full quantum state tomography and coherence time of the atomic qubit.
From: Deterministic spin-photon entanglement from a trapped ion in a fiber Fabry–Perot cavity
a Absolute values of the density matrix ρ obtained from a full quantum state tomography followed by a maximum likelihood estimation as described in methods. Errors are denoted with gray bars. b The experimental data show the visibility of a Ramsey like sequence for different evolution times between the two π/2 pulses. The visibility for each evolution time is determined by scanning the relative phase between the pulses (inset). Blue circles: The Zeeman qubit \(\left|{g}^{\pm }\right\rangle\) exhibits a coherence time of (496 ± 42) μs. Yellow triangles: The hyperfine qubit \(\left|{g}^{+}\right\rangle /\left|0\right\rangle\) exhibits a coherence time of (1022 ± 121) μs. The times are extracted from fits (solid lines) with the function \(\exp \left(-\left(t/\tau \right)\right)\). Error bars show the standard error.
