Abstract-Development of Aluminum LEKIDs for Balloon-Borne Far-IR Spectroscopy

S. Hailey-Dunsheath, A. C. M. Barlis, J. E. Aguirre, C. M. Bradford, J. G. Redford, T. S. Billings, H. G. LeDuc, C. M. McKenney, M. I. Hollister, 

https://arxiv.org/abs/1803.02470v1

We are developing lumped-element kinetic inductance detectors (LEKIDs) designed to achieve background-limited sensitivity for far-infrared (FIR) spectroscopy on a stratospheric balloon. The Spectroscopic Terahertz Airborne Receiver for Far-InfraRed Exploration (STARFIRE) will study the evolution of dusty galaxies with observations of the [CII] 158 μm and other atomic fine-structure transitions at z=0.5−1.5, both through direct observations of individual luminous infrared galaxies, and in blind surveys using the technique of line intensity mapping. The spectrometer will require large format (∼1800 detectors) arrays of dual-polarization sensitive detectors with NEPs of 1×10−17 W Hz−1/2. The low-volume LEKIDs are fabricated with a single layer of aluminum (20 nm thick) deposited on a crystalline silicon wafer, with resonance frequencies of 100−250 MHz. The inductor is a single meander with a linewidth of 0.4 μm, patterned in a grid to absorb optical power in both polarizations. The meander is coupled to a circular waveguide, fed by a conical feedhorn. Initial testing of a small array prototype has demonstrated good yield, and a median NEP of 4×10−18 W Hz−1/2.

Abstract-Single photon detection of 1.5 THz radiation with the quantum capacitance detector

P. M. Echternach, B. J. Pepper, T. Reck,  C. M. Bradford

https://www.nature.com/articles/s41550-017-0294-y

Far-infrared spectroscopy can reveal secrets of galaxy evolution and heavy-element enrichment throughout cosmic time, prompting astronomers worldwide to design cryogenic space telescopes for far-infrared spectroscopy. The most challenging aspect is a far-infrared detector that is both exquisitely sensitive (limited by the zodiacal-light noise in a narrow wavelength band, λ/Δλ ~1,000) and array-able to tens of thousands of pixels. We present the quantum capacitance detector, a superconducting device adapted from quantum computing applications in which photon-produced free electrons in a superconductor tunnel into a small capacitive island embedded in a resonant circuit. The quantum capacitance detector has an optically measured noise equivalent power below 10−20 W Hz−1/2 at 1.5 THz, making it the most sensitive far-infrared detector ever demonstrated. We further demonstrate individual far-infrared photon counting, confirming the excellent sensitivity and suitability for cryogenic space astrophysics.