Fig. 9: Inter-ququart CZ gate performance.
From: An architecture for two-qubit encoding in neutral ytterbium-171 atoms
a Accrued phases φ for all two-ququart basis states in units of π as a function of Δ/Ω for η = 0.989, corresponding to the weighting values shown in Table 1, and overall Rydberg energy shift 2 GHz. Lines are colored by the number of 1's in the “o” positions of both atoms' ququart bitstrings—0 (purple), 1 (blue), and 2 (orange), giving distinct accruals φ0, φ1, and φ2, respectively. The dot-dash patterns of each of the lines correspond to their associated states' two-ququart bitstrings. The CZ gate protocol from ref. 47 is implemented for 2φ1 − π = φ2 (red points). b CZ gate infidelities as a function of η ∈ [−1, 1], parameterizing the uniformity of the Rydberg interaction between the various states of the 59 3S1 manifold. The lines of different opacities show the gate infidelity for varied overall energy shift from 30 GHz (most opaque) to 50 MHz (least opaque), with equal logarithmic spacing. The condition used in (a) is shown in red. Note that the authors of ref. 33 estimate their shift to be of size ≈26 GHz.
