Overcoming Stark-shift constraints in phase-controlled Rydberg two-qubit gates
Phys. Rev. A 114, 032618 – Published 22 September, 2026
DOI: https://doi.org/10.1103/qn5y-77d4
Abstract
We investigate the effect of nonresonant two-photon excitation on the design of Rydberg two-qubit phase gates for nonindependently addressed qubits. We show that Stark shifts due to nonresonant intermediate states introduce additional phases, constraining the set of entangling gates that can be realized via two-photon transitions in the strong-Rydberg-blockade limit. For the two controlled- z (cz) gates distinguished by the sign of the trace of their matrix representations, we demonstrate high-fidelity implementations using a three-pulse sequence, without additional single-qubit operations to correct the two-qubit phase, by controlling the absolute phases and field amplitudes of the pulses applied to each qubit. Based on these insights, we introduce robust control schemes tailored to each cz gate, yielding high-fidelity protocols with pulse sequences containing either an even or an odd number of pulses.
