AQP Seminar: Ultrasensitive bolometry with Josephson junctions

Aalto Quantum Physics -seminaari (Nanotalo). Puhuja: Dr. Jean-Philippe Girard (Department of Applied Physics, Aalto University)

Sensitive microwave detection is highly desirable for circuit quantum electrodynamics (cQED) and astrophysical applications. More practicals domains would also benefit from such improvements, such as gas detection, homeland security, THz imaging or medical applications.
In this talk, we investigate the performance of bolometers based on Josephson junctions. 
A bolometer is a device composed of an absorber and a thermometer. The absorber converts an incident electromagnetic signal into a temperature rise of the material and the thermometer (here based on Josephson junctions) enables to quantify the amplitude of this heating. Due to its unusual thermal properties, graphene is a promising material for the absorber. We have experimentally studied a graphene-based bolometer. Our preliminary results suggest a noise equivalent power of NEP = 20 zW/ rtHz with a thermal time constant of 800 ns and a calorimetric energy resolution of h*22 GHz.
We will also introduce a bolometer supplemented by a dc heater line, which enables traceable power absorption measurements.