Researchers from Chalmers University of Technology have demonstrated a detector made from graphene that could revolutionize the sensors used in next-generation space telescopes. The findings were recently published in the scientific journal Nature Astronomy .
Beyond superconductors, there are few materials that can meet the requirements needed to make ultra-sensitive and fast terahertz (THz) detectors for astronomy. Chalmers researchers have shown that engineered graphene adds a new material paradigm for THz heterodyne detection.
“Graphene might be the only known material that remains an excellent conductor of electricity / heat even when having, effectively, no electrons. We have reached a near zero-electron scenario in graphene, also called Dirac point, by assembling electron-accepting molecules on its surface. Our results show that graphene is an exceptionally good material for THz heterodyne detection when doped to the Dirac point, ”says Samuel Lara-Avila, assistant professor at the Quantum Device Physics Laboratory and lead author of the paper.
Another crucial aspect for the THz graphene detector is the extremely low power needed for the local oscillator to achieve a reliable detection of faint THz signals, Few orders of magnitude lower than superconductors require. This could enable quantum-limited THz coherent detector arrays, hence opening the door to 3D imaging of the universe.
Elvire De Beck, astronomer at the Department of Space, Earth and Environment, who did not take part in the research, explained the possible implications for practical astronomy:
“This graphene-based technology has enormous potential for future space missions that aim at eg unveiling how water, carbon, oxygen and life itself came to earth. A lightweight, power efficient 3D imager that is quantum-limited at terahertz frequencies is crucial for such ambitious tasks. But, at the moment, THz 3D imagers are simply not available. ”
Sergey Kubatkin, professor at the Quantum Device Physics Laboratory and co-author of the paper, explained:
“ The core of the THz detector is the system of graphene and molecular assemblies. This is in itself a novel composite 2D material that deserves deeper investigation from a fundamental point of view, as it displays a whole new charge / heat transport regime governed by quantum-mechanical effects. ”
References : “Towards quantum-limited coherent detection of terahertz waves in charge-neutral graphene” by S. Lara-Avila, A. Danilov, D. Golubev, H. He, K. H. Kim, R. Yakimova, F. Lombardi, T. Bauch , S. Cherednichenko and S. Kubatkin, 5 August 2019, Nature Astronomy .
DOI: 10.1038 / s41550-019-0843-7