Proposal for a continuous wave laser with linewidth well below the standard quantum limit.

Area of Science:

• Quantum Optics
• Superconducting Circuits
• Laser Physics

Background:

• Lasers are essential scientific tools due to their high coherence.
• Conventional lasers are limited by quantum noise, affecting their linewidth.
• The standard quantum limit defines a fundamental noise threshold.

Purpose of the Study:

• To propose and analyze a novel superconducting microwave laser design.
• To overcome the standard quantum limit for laser linewidth.
• To reduce noise by engineering photon coupling in the laser cavity.

Main Methods:

• Theoretical analysis of a superconducting circuit.
• Design incorporating Josephson junctions, capacitors, and inductors.
• Engineering of low-noise couplers for the gain medium, cavity, and output port.

Main Results:

• Demonstrated a method to eliminate most noise from photons entering/leaving the laser cavity.
• Proposed a design that can reduce laser linewidth below the standard quantum limit.
• Achieved a linewidth reduction factor equal to the number of photons in the cavity.

Conclusions:

• Quantum engineering techniques can surpass conventional limits in quantum systems.
• The proposed superconducting microwave laser offers enhanced performance.
• This work highlights the potential of superconducting quantum information for classical systems.