Graphene-based Josephson junction microwave bolometer

Area of Science:

• Physics
• Materials Science
• Quantum Technology

Background:

• Sensitive microwave detectors are crucial for radio astronomy, dark-matter axion searches, and quantum information science.
• Conventional bolometers face limitations in photon coupling and material stability due to their large surface-to-volume ratio.
• Nanofabrication of smaller devices is the typical approach to enhance bolometer sensitivity.

Purpose of the Study:

• To present an ultra-thin bolometric sensor based on monolayer graphene.
• To overcome the limitations of conventional bolometers by utilizing graphene's unique thermal and electronic properties.
• To achieve unprecedented sensitivity in microwave detection.

Main Methods:

• Developed a superconductor-graphene-superconductor Josephson junction bolometer.
• Embedded the Josephson junction in a microwave resonator with 7.9 GHz resonance frequency and >99% coupling efficiency.
• Utilized graphene's low electronic specific heat and thermal conductivity.

Main Results:

• Achieved a noise-equivalent power of 7 × 10⁻¹⁹ W/√Hz.
• Demonstrated an energy resolution equivalent to a single 32 GHz photon.
• Reached the fundamental limit of sensitivity imposed by thermal fluctuations at 0.19 K.

Conclusions:

• Monolayer graphene enables the development of ultra-sensitive bolometric sensors.
• The superconductor-graphene-superconductor Josephson junction bolometer represents a significant advancement in detector technology.
• Two-dimensional materials hold promise for creating bolometers at the thermodynamic limit.