Rydberg-Mediated Entanglement in a Two-Dimensional Neutral Atom Qubit Array.

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Computing

Background:

• Scalable quantum computing requires high-fidelity entanglement between multiple qubits.
• Rydberg blockade is a key mechanism for achieving two-qubit gates in neutral atom systems.
• Previous experiments faced challenges in maintaining high fidelity in large qubit arrays.

Purpose of the Study:

• To demonstrate high-fidelity two-qubit Rydberg blockade and entanglement in a large two-dimensional atomic qubit array.
• To improve Bell state fidelity beyond previous experimental records.
• To identify dominant error sources affecting gate fidelity.

Main Methods:

• Utilized a 121-site two-dimensional array of atomic qubits defined by blue detuned light lines.
• Implemented improved experimental techniques to enhance Rydberg blockade and entanglement.
• Employed quantum process matrices for detailed error analysis.

Main Results:

• Achieved a high observed Bell state fidelity of F_{Bell}=0.86(2).
• Inferred corrected fidelities of F_{Bell}^{-SPAM}=0.88 (post-SPAM correction) and F_{Bell}^{C_{Z}}=0.89 (post-single-qubit gate correction).
• Identified finite atom temperature and laser noise as primary contributors to gate infidelity.

Conclusions:

• Demonstrated a significant advancement in high-fidelity entanglement generation within a large-scale atomic qubit array.
• The inferred fidelity of the Rydberg-mediated C_{Z} gate is 0.89.
• Finite atom temperature and laser noise are critical factors to address for further improvements in quantum gate performance.