Breaking the Entangling Gate Speed Limit for Trapped-Ion Qubits Using a Phase-Stable Standing Wave

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Computing

Background:

• Conventional laser-driven entangling operations for trapped-ion qubits lack optical phase control, limiting independent tuning of carrier and motional coupling.
• This limitation imposes a speed limit on Mølmer-Sørensen gates, a crucial component in quantum information processing.

Purpose of the Study:

• To overcome the limitations of conventional laser-driven entangling operations.
• To achieve independent tuning of carrier and motional coupling in trapped-ion qubits.
• To enhance the speed and precision of quantum gates.

Main Methods:

• Utilized a λ=674 nm standing wave laser field with precisely controlled ion position (≈λ/100) for ^{88}Sr^{+} ions.
• Suppressed off-resonant carrier coupling by a factor of 18.
• Coherently enhanced spin-motion coupling.

Main Results:

• Demonstrated suppression of carrier coupling, surpassing the speed limit imposed by conventional methods.
• Achieved a significantly reduced gate duration of 15 microseconds.
• Identified available laser power as the current limitation for further speed enhancement.

Conclusions:

• The developed standing wave technique enables faster and more controlled entangling operations for trapped-ion qubits.
• This advancement is critical for improving the efficiency of quantum information processing.
• Future work can focus on increasing laser power to further reduce gate times.