Demonstration of an ac Josephson junction laser

Area of Science:

• Superconducting electronics
• Quantum optics
• Solid-state physics

Background:

• Superconducting devices offer high speeds and low energy loss, making them promising for computing.
• Demonstrating coherence, such as lasing, is crucial for advancing superconducting technologies.
• The ac Josephson effect is a fundamental property of superconductors with potential for photon generation.

Purpose of the Study:

• To demonstrate a superconducting laser utilizing the ac Josephson effect.
• To achieve efficient on-chip generation of coherent microwave photons at low temperatures.
• To explore the integration of Josephson junction-based lasers with quantum devices.

Main Methods:

• Fabricated a Josephson junction strongly coupled to a superconducting cavity.
• Applied a DC voltage bias across the Josephson junction to generate microwave photons.
• Utilized circuit nonlinearity for down-conversion of Josephson frequencies to the cavity's fundamental mode.

Main Results:

• Successfully demonstrated lasing using a Josephson junction and superconducting cavity.
• Achieved efficient down-conversion of higher-order Josephson frequencies to the cavity's fundamental mode.
• Showcased the potential for on-chip generation of coherent microwave photons.

Conclusions:

• Superconducting lasers based on the ac Josephson effect are feasible.
• This technology enables efficient, low-temperature microwave photon generation for quantum applications.
• The simple design facilitates integration with other quantum electronic devices.