Model Predicts 99.8% Fidelity for Dual-Species Rydberg Gates by Suppressing Two-Photon Crosstalk

The arXiv preprint develops a master-equation model that explicitly includes off-resonant excitation pathways between the two rubidium isotopes during two-photon Rydberg excitation. By choosing appropriate intermediate-state detunings and intensity ratios, the authors demonstrate that crosstalk-induced phase errors and population leakage can be canceled to first order without requiring additional laser fields or species-selective optics.

This approach directly addresses a key scalability barrier in neutral-atom arrays, where dual-species operation is pursued for mid-circuit readout and sympathetic cooling. Prior single-species gate studies achieved comparable fidelities only after extensive calibration; the new design tolerates realistic intensity imbalances up to 5% while maintaining the target error budget.

The work remains purely numerical. Experimental validation on an 85Rb/87Rb array with single-atom resolution would be required to confirm the predicted robustness against laser phase noise and atomic-motion effects. If realized, the scheme could accelerate fault-tolerant neutral-atom processors by enabling higher-fidelity entangling operations between data and ancilla qubits.