诺斯洛普·格鲁曼公司

Direct spectroscopy is very promising approach to characterizing the atmospheres of nearby rocky exoplanets. Non-common path aberrations (NCPA) are differential aberrations between the science optical path and the adaptive optics optical path. The NCPA leak through the coronagraph and create speckles that mimic exoplanet signals. This limits the sensitivity of high-contrast imaging instruments at close angular separations - exactly the separations where we want to search for rocky exoplanets with current and future telescopes and instruments. We aim to actively remove the NCPA on-sky during observations by using focal plane wavefront sensing and control with the newly upgraded MagAO-X instrument. MagAO-X is equipped with a unique second-stage Adaptive Optics (AO) system. The second-stage AO system contains a dedicated deformable mirror (DM) for coronagraphic focal plane wavefront control. This DM is placed after the science and AO beam-splitter and is therefore not seen by the main AO loop. The DM has been recently upgraded from an ALPAO-97 to a Boston Micromachine Kilo-DM. The new Kilo-DM enables focal plane wavefront control with the implicit Electric Field Conjugation (iEFC) algorithm. We developed the necessary procedures to run iEFC with MagAO-X on-sky. We demonstrated the successful removal of NCPA on-sky with an iEFC interaction matrix that was calibrated on the MagAO-X internal source. This demonstrates the repeatability between our off-sky and on-sky alignment. The iEFC algorithm was tested on HR4796A and Alpha Centauri in 0.5" seeing conditions. We saw a reduction of the NCPA by a factor of 2 to 20. This on-sky validation confirms the robustness and efficiency of iEFC under realistic observing conditions, paving the way for its integration into next-generation AO systems for the Extremely Large Telescope and Giant Magellan Telescope.

The next generation of Extremely Large Telescopes (ELTs) and the Habitable Worlds Observatory (HWO) require active speckle suppression to directly image exo-Earths. Focal plane wavefront sensing and control allows us to detect and remove time-varying speckles through measurements of the electric field. Wavefront sensing approaches include pairwise probing (PWP) and the self-coherent camera (SCC). However, the PWP technique is time-consuming, requiring at least 4 images and reducing the speed at which aberrations can be eliminated. The classical SCC modifies a standard coronagraph design, creating a reference electric field that interferes with speckles in the final focal plane, forming Fizeau fringes. However, this design only works over small spectral bandwidths and requires significantly oversized optics, limiting its effectiveness. We demonstrate a new SCC variant, the Spatially-Clipped SCC (SCSCC). The SCSCC utilizes a pinhole placed close to the Lyot stop, reducing the overall beam footprint and boosting the sensor's spectral bandwidth by factors of 3, respectively. A beamsplitter and knife edge downstream of the Lyot stop splits the light into 2 channels: fringed and unfringed, enabling wavefront sensing with a single exposure. Time-varying speckles are frozen in place, making them easy to remove. We present the SCSCC optical design combined with the photon resolving Hamamatsu Orca-Quest 2 camera. Furthermore, we demonstrate high speed wavefront control with the SCSCC, minimizing speckle intensity by 2x within a 5-11 lambda/D dark hole region on the Comprehensive Adaptive Optics and Coronagraph Test Instrument (CACTI) at the University of Arizona. These lab tests are in preparation for an on-sky demonstration of the SCSCC with the MagAO-X instrument. Our results make the SCSCC a valuable wavefront sensor for upcoming missions, including the Giant Magellan Telescope and HWO.

Incoming starlight is refracted as it enters Earth's atmosphere from the vacuum of space. The wavelength-dependence of atmospheric refraction causes elongation of the broadband PSF of ground-based telescopes, especially in the visible spectrum. The result is degraded image quality alongside reduced coronagraph light-blocking efficiency, both of which limit high-contrast observations. An atmospheric dispersion corrector (ADC) is a dispersive optic used to compensate for this effect. Current methods for dispersion compensation use analytical models to anticipate dispersion strength based on parameters such as site altitude and telescope zenith angle; however, dispersion strength is also dictated by a number of factors that cannot be measured, including instantaneous humidity, temperature, and pressure along the line of sight to the star. This leads to constant over- or under-correction of the true atmospheric dispersion by the ADC. In this work, we use the Magellan extreme adaptive optics system MagAO-X at Las Campanas Observatory to measure and correct residual atmospheric dispersion in real-time. The amount of residual dispersion is encoded in the orientation of satellite spots generated by using MagAO-X's deformable mirror as a diffraction grating. We have used these real-time measurements as feedback for closed-loop control of the ADCs on-sky at visible and NIR wavelengths, reducing residual atmospheric dispersion down to sub-mas/μm levels. Active atmospheric dispersion correction on MagAO-X is a precursor to high-contrast imaging with Extreme AO for the upcoming Extremely Large Telescopes, where high-precision dispersion compensation will be required to image exoplanets in reflected light.

A lingering technical challenge for pyramid wavefront sensors (PyWFS) is their change in response between calibration and correction residuals, a quantity known as optical gain (OG). Given the prevalent use of PyWFSs in current and planned high contrast adaptive optics (AO), understanding and reliably measuring OG for realtime control unlocks advanced correction and post processing techniques. The OG quantity as an unknown inhibits a system's ability to stably correct non common path errors, reconstructing wavefronts, and PSF reconstruction. This work compares kinds of optical gain measurement techniques on MagAO-X, a visible light extreme AO instrument on the 6.5m Magellan Clay telescope. We present a set of on-sky measurements of OG across three techniques: 1) An on-sky calibration that acquires OG per spatial mode, 2) realtime measurements of the instantaneous Strehl Ratio (SR) on the pyramid tip, and 3) realtime measurement of known, high-frequency probe signal on the WFS itself. We compare these on-sky results with performance diagnostics to asses how faithfully OG is returned. We conclude with future steps for active control of OG on MagAO-X.

We measure the effect of ionizing radiation on superconducting qubits with a timing resolution of 1 μs using microwave kinetic inductance detectors (MKIDs) fabricated on the same substrate. We observe no correlation between two-level system (TLS) scrambling events and ionizing radiation events detected with the MKIDs, suggesting TLS scrambling events may not arise from ionizing radiation and instead the previously reported apparent correlation may be due to events without sufficient energy to trigger our MKIDs. We characterize the fast-time system recovery of transmons following a radiation event, where we observe the recovery of the enhanced qubit relaxation and excitation to be well-described by an exponential recovery to the baseline quasiparticle density, with a characteristic time of 13±1 μs, and a peak quasiparticle density at the junction per deposited energy of 240/μm^3/MeV. The fast recovery is consistent with literature reported values for Nb-based devices with direct injection of 2Δ_Al phonons, demonstrating the recovery is strongly dependent on the proximity of niobium to the junction.