Individually addressed entangling gates in a two-dimensional ion crystal.

Area of Science:

• Quantum Information Processing
• Atomic Physics
• Condensed Matter Physics

Background:

• Two-dimensional (2D) ion crystals offer a scalable platform for quantum information processing.
• Challenges remain in achieving high-fidelity, individually addressed two-qubit gates due to ion micromotion and 2D addressing difficulties.

Purpose of the Study:

• To demonstrate high-fidelity two-qubit entangling gates between any ion pairs in a 2D ion crystal.
• To address the technical challenges of individual ion addressing and micromotion in 2D ion crystals for quantum computing.

Main Methods:

• Utilized symmetrically placed crossed acousto-optic deflectors (AODs) to drive Raman transitions for precise ion addressing.
• Developed a gate sequence involving alternating single-ion addressing to avoid crosstalk from multiple laser beams.
• Investigated the impact of ion micromotion on gate fidelity and proposed compensation methods.

Main Results:

• Achieved an addressing crosstalk error below 0.1% using crossed AODs.
• Demonstrated two-qubit entangling gates compatible with any single-ion addressing technique.
• Showed that the effect of ion micromotion on gate fidelity can be compensated by recalibrating laser intensity.

Conclusions:

• Successfully demonstrated a method for high-fidelity two-qubit entangling gates in 2D ion crystals.
• Overcame key challenges in individual ion addressing and micromotion, crucial for scalable quantum computing.
• This work advances the development of ion trap quantum computers with hundreds to thousands of qubits.