Scalable narrow linewidth high power laser for barium ion optical qubits

Area of Science:

• Quantum Information Science
• Laser Physics
• Atomic, Molecular, and Optical Physics

Background:

• Laser linewidth is critical for high-fidelity ion trap quantum processors and optical clocks.
• Scaling quantum computing requires higher laser power with ultra-narrow linewidths.
• Fiber amplifiers offer a promising approach to meet these demands.

Purpose of the Study:

• To evaluate thulium-doped fiber amplifiers (TDFAs) for barium ion qubit manipulation.
• To assess if TDFAs introduce significant linewidth broadening in seed lasers.
• To demonstrate high-fidelity quantum gates with minimal intensity noise.

Main Methods:

• Utilized a delayed self-heterodyne method with Voigt fitting for linewidth measurement.
• Employed quadrupole spectroscopy with trapped barium ions for corroboration.
• Measured linewidth independently using two distinct techniques.

Main Results:

• TDFAs were shown to not significantly broaden the linewidth of seed lasers.
• Achieved linewidth values of 160 ± 15 Hz (Voigt fitting) and 156 ± 16 Hz (quadrupole spectroscopy).
• Demonstrated high-fidelity gates with minimal intensity noise introduction.

Conclusions:

• TDFAs are effective for high-power, narrow-linewidth laser generation in ion trap quantum computing.
• Measurement techniques confirm the reliability of linewidth preservation.
• Findings advance laser linewidth control for quantum technologies and extend tunable laser availability.