Subnatural Linewidth Superradiant Lasing with Cold ^{88}Sr Atoms

Area of Science:

• Atomic physics
• Quantum optics
• Laser technology

Background:

• Superradiant lasers utilize collective atomic effects for enhanced coherence.
• They operate in the bad-cavity regime, storing phase information in atomic spin states.
• Potential for significantly narrower linewidths compared to conventional lasers.

Purpose of the Study:

• Investigate superradiant lasing properties in ultracold strontium-88 atoms within an optical cavity.
• Extend superradiant emission duration and achieve steady-state parameters.
• Explore linewidth reduction capabilities for potential continuous superradiant laser emulation.

Main Methods:

• Utilized an ensemble of ultracold ^{88}Sr atoms.
• Employed an optical cavity setup to confine the atomic medium.
• Fine-tuned repumping rates to achieve steady-state lasing parameters.
• Measured the lasing linewidth on the ^{3}P_{1}→^{1}S_{0} intercombination line.

Main Results:

• Extended superradiant emission to several milliseconds.
• Observed steady parameters enabling emulation of continuous superradiant laser performance.
• Achieved a lasing linewidth of 820 Hz over 1.1 ms of operation.
• Demonstrated linewidth reduction nearly an order of magnitude below the natural linewidth.

Conclusions:

• Superradiant lasers in ultracold atoms offer a pathway to ultra-narrow linewidths.
• Steady-state operation is achievable by controlling repumping rates.
• This work paves the way for advanced applications requiring highly coherent light sources.