K. V. Kozenko | Searcharxiv

arXiv2026

Numerically optimized amplitude-robust controlled-Z gate for ultracold neutral atoms with individual addressing capability

We numerically optimized a scheme for a neutral atom Rydberg blockade symmetric controlled-Z (CZ) gate to increase its robustness to variations in the Rabi frequency. This gate scheme uses analytically defined phase profiles of the laser pulse and demonstrates increased robustness to variations in the Rabi frequency almost by an order of magnitude compared to previous proposals. We demonstrate the applicability of our gate protocol to individual addressing in Rydberg excitation, taking into account the asymmetry of Rabi frequencies for two atoms that are individually excited by tightly focused laser beams. This allows for reducing the effects of residual thermal motion of trapped atoms and beam pointing instability on gate fidelities. We investigated the performance of our gate protocol for single-photon and two-photon Rydberg excitation schemes and showed its advantages for individual addressing at finite temperatures of trapped atoms.

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arXiv2025

Symmetric $C_Z$ gate for ultracold neutral atoms based on counterdiabatic driving at Rydberg excitation

We designed a scheme for a neutral atom Rydberg blockade $C_Z$ gate based on the double sequence of adiabatic pulses applied symmetrically to both atoms and using counterdiabatic driving for Rydberg excitation. This provides a substantial reduction in the quantum gate operation time compared to previously proposed double adiabatic schemes, and makes our scheme competitive with modern time-optimal protocols for high-fidelity entangling gates with neutral atoms. Our approach creates a bridge between fully adiabatic and time-optimal gate schemes. The use of adiabatic passage reduces the sensitivity of gate fidelity to variations in laser intensity, while counterdiabatic driving provides short gate times. The intensity and phase profiles of the laser pulse acting on the atoms are described analytically depending only on the gate duration. We demonstrated the applicability of this scheme for single-photon and two-photon schemes of Rydberg excitation in rubidium and cesium atoms, and, for the first time, discussed the implementation of a $C_Z$ gate using three-photon excitation of rubidium atoms. In contrast to many modern $C_Z$ gate protocols, our scheme does not generate intrinsic single-qubit phase shifts, although they still appear in two-photon configuration. We also designed a numerically optimized amplitude-robust gate with an analytically defined phase profile of the laser pulse and compared its performance with the counteradiabatic gate scheme.

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