EXoplanet SpectrosCopy using 0-nOise Photon Energy resolving Detectors

forthcoming

The question: ‘are we alone in the universe?’, is a central question in astronomy. It has become even more relevant due to the discovery of exoplanets within the habitable zone around their star. The presence of life could be determined from biomarkers in the spectrum of a planet’s atmosphere. However, an Earth-like planet around a Sun-like star is very faint, after suppressing the starlight. A crucial technology is therefore a noiseless, photon-counting detector, which resolves the energy of each photon. For NASA’s new flagship mission Habitable Worlds Observatory (HWO), detectors have been identified as a large technology-gap with high impact, a gap that should be closed before 2030. Established semiconductor detectors have too high noise, and no energy-resolution. I propose to close this technology gap using energy-resolving microwave kinetic inductance detectors (MKIDs), for visible to near-infrared wavelengths. A single photon generates thousands of excitations in the detector, which gives a direct measure of the photon energy. MKIDs have zero dark current and read noise, and a theoretical intrinsic resolving power of R>150. This enables the detection of biomarkers within each pixel. My group has recently realised three breakthroughs. We have measured R=70 at 402 nm, developed an antireflection coating and a fabrication method that improves yield. I will use these key ingredients to realise a 32 kpixel MKID instrument which meets the HWO specs: R>140 at 1 μm wavelength, an absorption efficiency >90%, and negligible dark counts, with >95% pixel yield. With this proposal, I will enable noiseless exoplanet spectroscopy in space and on ground, and raise the TRL level to ~TRL5 by 2030, in line with the current HWO schedule. A European detector contribution could close a major technology gap of HWO. MKIDs will play a key role for high-contrast imaging on the new extremely large telescope (E-ELT) as wavefront sensor and focal plane detector.