A team of US researchers have developed an ultra-sensitive micorwave sensor, or bolometer, using graphene.
The group from Harvard University, The Institute of Photonic Sciences, Massachusetts Institute of Technology, Pohang University of Science and Technology and Raytheon BBN Technologies, was partly funded by the US Army. The sensitivity of the bolometer can be used to improve thermal imaging designs, radio communications, and lidar and radar systems.
"The microwave bolometer developed under this project is so sensitive that it is capable of detecting a single microwave photon," said Dr. Joe Qiu, program manager for solid-state electronics and electromagnetics at the Army Research Office, an element of the U.S. Army Combat Capabilities Development Command's Army Research Laboratory. "This technology will potentially enable new capabilities for applications such as quantum sensing and radar.”
The graphene bolometer measures the temperature rise in superconducting Josephson junction while maintaining a high microwave radiation coupling by using graphene in the antenna. The electrons in the 2D layer of graphene are in a very special band structure in which the valence and conduction bands meet at only one point, known as Dirac point.
"The density of states vanishes there so that when the electrons receive the photon energy, the temperature rise is high while the heat leakage is small," said Dr. Kin Chung Fong at Raytheon BBN Technologies.
The increased sensitivity of bolometer detector can be used to improve the performance of systems detecting electromagnetic signal such as radar, night vision, Lidar and communication. It could also enable new applications such as quantum information science, thermal imaging as well as the search of dark matter.
The part of the research conducted at MIT included work from the Institute for Soldier Nanotechnologies. The US Army established the institute in 2002 as an interdisciplinary research centre.