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Updated: Aug 14, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Cosmic 21 cm delensing of microwave background polarization and the minimum detectable energy scale of inflation
Kris Sigurdson1, Asantha Cooray
1California Institute of Technology, Mail Code 130-33, Pasadena, California 91125, USA. ksigurds@tapir.caltech.edu
Abstract:
We propose a new method for removing gravitational lensing from maps of cosmic microwave background (CMB) polarization anisotropies. Using observations of anisotropies or structures in the cosmic 21 cm radiation, emitted or absorbed by neutral hydrogen atoms at redshifts 10 to 200, the CMB can be delensed. We find this method could allow CMB experiments to have increased sensitivity to a background of inflationary gravitational waves (IGWs) compared to methods relying on the CMB alone and may constrain models of inflation which were heretofore considered to have undetectable IGW amplitudes.
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