Optimal Control for Rydberg multi-qubit operations

TL;DR

This paper uses quantum optimal control to design continuous laser pulses for multi-qubit gates on Rydberg atoms, achieving high fidelity and robustness, which simplifies quantum operations and reduces decoherence.

Contribution

It introduces a method to implement multi-qubit gates directly with optimized laser pulses, improving efficiency and robustness over traditional gate decomposition.

Findings

Achieved 99.74% fidelity for Fredkin gate under realistic noise conditions.

Reduced operation time and decoherence through optimal control techniques.

Provided continuous protection of atoms from environmental noise.

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, -NOT 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 99.74\% fidelity while accounting for imperfections such as spontaneous emission, laser fluctuations, and Doppler dephasing.