Optimal model for fewer-qubit CNOT gates with Rydberg atoms

Fewer-qubit quantum logic gate, serving as a basic unit for constructing universal multiqubit gates, has been widely applied in quantum computing and quantum information. However, traditional constructions for fewer-qubit gates often utilize a multi-pulse protocol which inevitably suffers from serious intrinsic errors during the gate execution. In this article, we report an optimal model about universal two- and three-qubit CNOT gates mediated by excitation to Rydberg states with easily-accessible van der Waals interactions. This gate depends on a global optimization to implement amplitude and phase modulated pulses via genetic algorithm, which can facilitate the gate operation with fewer optical pulses. Compared to conventional multi-pulse piecewise schemes, our gate can be realized by simultaneous excitation of atoms to the Rydberg states, saving the time for multi-pulse switching at different spatial locations. Our numerical simulations show that a single-pulse two(three)-qubit CNOT gate is possibly achieved with a fidelity of 99.23$\%$(90.39$\%$) for two qubits separated by 7.10 $\mu$m when the fluctuation of Rydberg interactions is excluded. Our work is promising for achieving fast and convenient multiqubit quantum computing in the study of neutral-atom quantum technology.