Optimal control for Rydberg multi-qubit operations

Abstract

Quantum computing algorithms can be decomposed into a universal set of elementary one- and two-qubit gates. Different physical implementations of quantum computing, however, employ interactions that permit direct conditional dynamics on multiple qubits in a single step. In this work, we leverage quantum optimal control techniques to design single continuous laser pulses that implement multi-qubit controlled-phase and -swap (Fredkin) gates on Rydberg atom quantum processors. The identification of robust multi-qubit operations leads to reduced operation time and less decoherence, and the control field provides continuous protection of the atoms from environmental noise. Notably, we find that the controlled-SWAP (Fredkin) gate, implemented using this approach, achieves 99.88% fidelity while accounting for imperfections such as spontaneous emission, laser fluctuations, and Doppler dephasing.