Implementation of two-qubit Rydberg operations on neutral Rb-87 atoms in systems with different intermediate states

This work presents an experimental setup for implementing two-qubit operations on neutral atoms (${}^{87}$Rb) with the possibility of using two different Rydberg excitation schemes. One of them uses 5P${}_{1\mathrm{/}2}$ as the intermediate level and applies the second-stage beam locally to the addressed atoms. The second scheme uses the 6P${}_{3\mathrm{/}2}$ level; in this scheme, the particles to be entangled are moved to a separate zone through which both Rydberg beams pass. The advantages and limitations of both schemes are analyzed. Based on numerical modeling performed with a Julia package developed by the authors, it is demonstrated that the spatial configuration has a greater effect on quantum-operation fidelity than the choice of intermediate level. An experimental implementation of the scheme using the 6P${}_{3\mathrm{/}2}$ level is demonstrated, making it possible to achieve a two-qubit operation fidelity of 94%.