The Cosmic Microwave Background (CMB) radiation offers a unique window into the early Universe, facilitating precise examinations of fundamental cosmological theories. However, the quest for detecting B-modes in the CMB, predicted by theoretical models of inflation, faces substantial challenges in terms of calibration and foreground modeling. The COSMOCal (COsmic Survey of Millimeter wavelengths Objects for CMB experiments Calibration) project aims at enhancing the accuracy of the absolute calibration of the polarization angle $\psi$ of current and future CMB experiments. The concept includes the build of a very well known artificial source emitting in the frequency range [20-350] GHz that would act as an absolute calibrator for several polarization facilities on Earth. A feasibility study to place the artificial source in geostationary orbit, in the far field for all the telescopes on Earth, is ongoing. In the meanwhile ongoing hardware work is dedicated to build a prototype to test the technology, the precision and the stability of the polarization recovering in the 1 mm band (220-300 GHz). High-resolution experiments as the NIKA2 camera at the IRAM 30m telescope will be deployed for such use. Once carefully calibrated ($\Delta\psi$ < 0.1 degrees) it will be used to observe astrophysical sources such as the Crab nebula, which is the best candidate in the sky for the absolute calibration of CMB experiments.

Transferring the nanocrystals (NCs) from the laboratory environment toward practical applications has raised new challenges. In the case of NCs for display and lightning, the focus was on reduced Auger recombination and maintaining luminescence at high temperatures. When it comes to infrared sensing, narrow band gap materials are required and HgTe appears as the most spectrally tunable platform. Its low-temperature synthesis reduces the growth energy cost yet also favors sintering. As a result, once coupled to a read-out circuit, the Joule effect aggregates the particles leading to a poorly defined optical edge and dramatically large dark current. Here, we demonstrate that CdS shells bring the expected thermal stability (no redshift upon annealing, reduced tendency to form amalgams and preservation of photoconduction after an atomic layer deposition process). The peculiar electronic structure of these confined particles is unveiled using k.p self-consistent simulations showing a significant exciton biding energy at around 200 meV. After shelling, the material displays a p-type behavior that favors the generation of photoconductive gain. The latter is then used to increase the external quantum

It's fascinating to witness the significant progress achieved in leveraging colloidal nanocrystals as a viable platform for infrared optoelectronics. Their adaptability as a spin-coatable resist with infrared photoactive properties has spurred developments that transcend mere material advancements and delve deeply into advanced device design. A standout accomplishment in the infrared domain is the development of infrared cameras utilizing nanocrystal thin films as their active layers. This marks a paradigm shift in infrared imaging, challenging the long-held focus on high-quality monocrystalline thin films. The emergence of nanocrystal films, despite being highly polycrystalline, enables the fabrication of cost-effective sensors that are beginning to rival established technologies like InGaAs, especially in the short-wave infrared.Among potential materials, HgTe 1 stands out as the most versatile platform, capable of spanning the entire infrared spectrum from visible wavelengths for the most confined forms to THz 2 frequencies for bulk-like particles. In this presentation, I will begin by reviewing recent advancements in transitioning HgTe nanocrystal films from single-pixel sensors to high-quality imagers 34 .However, achieving such imagers marks just the beginning of the journey. One key challenge revolves around the interaction between light and matter. The polycrystalline nature, while enabling cost-effective sensors, does come with a trade-off – reduced mobility compared to bulk films, limiting the efficiency of charge collection. Therefore, introducing processes to focus light on a film thickness within which transport remains efficient becomes critical. In the latter part of the presentation, I will demonstrate how the incorporation of nanophotonic structures can introduce new functionalities such as actively reconfigurable spectral responses 5 and the extension of the device's spectral response into the mid-infrared range.The broad spectral tunability of HgTe nanocrystals also positions them favorably for thermal imaging. However, in this spectral range, the entire device architecture needs a reevaluation compared to visible wavelengths. Notably, the transparent conductive oxide layers typically used as electrodes exhibit weak transmission characteristics, necessitating alternative designs for transparent and conductive electrodes. Here, I will illustrate how the utilization of exalted transmission effects can enhance the design of high-performance mid-infrared sensors. 6 Schematic illustrating transformation of nanocrystal solution into an infrared focal plane array and finally exemple of image obtained with the imager

Context. The cosmic microwave background (CMB), a remnant of the Big Bang, provides unparalleled insights into the primordial universe, its energy content, and the origin of cosmic structures. The success of forthcoming terrestrial and space experiments hinges on meticulously calibrated data. Specifically, the ability to achieve an absolute calibration of the polarization angles with a precision of <0 degrees. 1 is crucial to identify the signatures of primordial gravitational waves and cosmic birefringence within the CMB polarization. Aims. We introduce the COSmological Microwave Observations Calibrator project, designed to deploy a polarized source in space for calibrating microwave frequency observations. The project aims to integrate microwave polarization observations from small and large telescopes, ground-based and in space, into a unified scale, enhancing the effectiveness of each observatory and allowing robust combination of data. Methods. To demonstrate the feasibility and confirm the observational approach of our project, we developed a prototype instrument that operates in the atmospheric window centered at 260 GHz, specifically tailored for use with the NIKA2 camera at the IRAM 30 m telescope. Results. We present the instrument components and their laboratory characterization. The results of tests performed with the fully assembled prototype using a Kinetic Inductance Detectors-based instrument, similar concept of NIKA2, are also reported. Conclusions. This study paves the way for an observing campaign using the IRAM 30 m telescope and contributes to the development of a space-based instrument.

The Cosmic Microwave Background (CMB) radiation offers a unique window into the early Universe, facilitating precise examinations of fundamental cosmological theories. However, the quest for detecting B-modes in the CMB, predicted by theoretical models of inflation, faces substantial challenges in terms of calibration and foreground modeling. The COSMOCal (COsmic Survey of Millimeter wavelengths Objects for CMB experiments Calibration) project aims at enhancing the accuracy of the absolute calibration of the polarization angle ψ of current and future CMB experiments. The concept includes the build of a very well known artificial source emitting in the frequency range [20-350] GHz that would act as an absolute calibrator for several polarization facilities on Earth. A feasibility study to place the artificial source in geostationary orbit, in the far field for all the telescopes on Earth, is ongoing. In the meanwhile ongoing hardware work is dedicated to build a prototype to test the technology, the precision and the stability of the polarization recovering in the 1 mm band (220-300 GHz). High-resolution experiments as the NIKA2 camera at the IRAM 30m telescope will be deployed for such use. Once carefully calibrated (Δψ < 0.1◦) it will be used to observe astrophysical sources such as the Crab nebula, which is the best candidate in the sky for the absolute calibration of CMB experiments.

This paper presents a new infrared imaging system, SIRIS (Short InfraRed Imaging System) that was entirely developed in LPENS of ENS Paris. It is designed around a hybrid CMOS InGaAs FPA from NIT (New Imaging Technologies). This detector was originally intended for industrial high dynamic applications, however through innovative controls and new readout methods, it became fully exploitable for low noise scientific applications. The SIRIS camera is aimed at cutting-edge applications, like astronomy ones, that can take advantage of all of its improved characteristics to gain in signal to noise ratio, dynamic, resolution and optimization of acquisition times. We took advantage of the availability of the 1 m telescope at the Pic du Midi Observatory to test the camera and develop it for astronomical applications with demanding requirements in terms of both detection and dynamic range. This system, with its specific SWIR sensor, will be presented, illustrated through its recent observational results.

Thanks to their remarkable spectral tunability across the entire infrared range, HgTe nanocrystals present a unique platform for designing infrared optoelectronic devices. While in recent years most of the significant advances in this domain have been made on devices at the single-pixel level, there is a growing trend toward exploring the potential of this material for imaging applications. However, until recently, focal plane arrays based on HgTe colloidal nanocrystals have been limited to the photoconductive mode, which is inherently associated with a large dark current. In this work, we demonstrate a diode stack compatible with a readout integrated circuit whose back-end processing has been optimized to ensure compatibility with a complete diode stack deposition. The diode design is also optimized to generate a Fabry–Pérot cavity in which 50% of the light is effectively absorbed at the band edge. Finally, taking benefit from the full video graphics array format, high-resolution images are taken.

GRANDMA is a world-wide collaboration with the primary scientific goal of studying gravitational-wave sources, discovering their electromagnetic counterparts and characterizing their emission. GRANDMA involves astronomers, astrophysicists, gravitational-wave physicists, and theorists. GRANDMA is now a truly global network of telescopes, with (so far) 30 telescopes in both hemispheres. It incorporates a citizen science programme (Kilonova-Catcher) which constitutes an opportunity to spread the interest in time-domain astronomy. The telescope network is an heterogeneous set of already-existing observing facilities that operate coordinated as a single observatory. Within the network there are wide-field imagers that can observe large areas of the sky to search for optical counterparts, narrow-field instruments that do targeted searches within a predefined list of host-galaxy candidates, and larger telescopes that are devoted to characterization and follow-up of the identified counterparts. Here we present an overview of GRANDMA after the third observing run of the LIGO/VIRGO gravitational-wave observatories in 2019-2020 and its ongoing preparation for the forthcoming fourth observational campaign (O4). Additionally, we review the potential of GRANDMA for the discovery and follow-up of other types of astronomical transients.

HgTe nanocrystals, thanks to quantum confinement, present a broadly tunable band gap all over the infrared spectral range. In addition, significant efforts have been dedicated to the design of infrared sensors with an absorbing layer made of nanocrystals. However, most efforts have been focused on single pixel sensors. Nanocrystals offer an appealing alternative to epitaxially grown semiconductors for infrared imaging by reducing the material growth cost and easing the coupling to the readout circuit. Here we propose a strategy to design an infrared focal plane array from a single fabrication step. The focal plane array (FPA) relies on a specifically designed readout circuit enabling in plane electric field application and operation in photoconductive mode. We demonstrate a VGA format focal plane array with a 15 μm pixel pitch presenting an external quantum efficiency of 4-5% (15% internal quantum efficiency) for a cut-off around 1.8 μm and operation using Peltier cooling only. The FPA is compatible with 200 fps imaging full frame and imaging up to 340 fps is demonstrated by driving a reduced area of the FPA. In the last part of the paper, we discuss the cost of such sensors and show that the latter is only driven by labor costs while we estimate the cost of the NC film to be in the 10-20 € range.

After the use of nanocrystals as light downconverters, infrared sensing appears to be one of the first market applications where they can be used while being both electrically and optically active. Over recent years, tremendous progress has been achieved, leading to an apparent rise in the technological-readiness level (TRL). So far, the efforts have been focused on PbS nanocrystals for operation in the near-infrared. Here, we focus on HgTe since its narrower band gap offers more flexibility to explore the extended short-wave and midwave infrared. We report a photoconductive strategy for the design of short-wave infrared focal plane arrays with enhanced image quality. An important aspect often swept under the rug at an early stage is the material stability. It appears that HgTe remains mostly unaffected by oxidation under air operation. The evaporation of Hg, a potentially dramatic aging process, only occurs at temperatures far beyond the focal plane array's standard working temperature. The main bottleneck appears to be the particle sintering resulting from joule heating of focal plane arrays. This suggests that a cooling system is required, whose first role is to prevent the material from sintering even before targeting dark current reduction.

Spectroscopy in the visible and near-infrared has been the main tool for characterising the surface properties of asteroids for decades. For a given target, the two wavelength regimes are usually acquired by different telescopes/instruments, separated by years. They are seldom obtained simultaneously. However, it is not straightforward to combine datasets from different sources because of the spectral reddening linked with phase angle. We present the first-light result of SOVAG (Spectrographe pour l’Observations dans le Visible et infrarouge proche d’Astéroïdes Géocroiseurs), a new concept of spectrograph for observing both wavelength ranges at the same time. It is compact in design and portable. We developed a prototype of this instrument between 2016 and 2018. In July 2018, we mounted SOVAG on the 1 m-telescope in Pic du Midi observatory (for which it was designed) and conducted its on-sky first light experiment. We present a spectrum of (4) Vesta which demonstrates the reliability of observations and the accuracy of the calibration. Ongoing development will allow us to push observation-limits toward fainter objects.

This paper presents a new method based on Non Destructive Readout (NDRO) to improve multi-exposure High Dynamic Range (HDR) Imaging. A sequence of Low-Dynamic Range (LDR) images can then be acquired during a single exposure. The concept enables the latency between LDR images to be removed as well as the intrinsic ghost artifacts observed using state-of-art HDR systems based on multi-exposures. The method has been applied to improve the performances of HDR sensor based on logarithmic pixels. Using the NDRO method, a Short Wave InfraRed (SWIR) camera has been designed to produce HDR IR videos. A real-time HDR video stream generation is achieved based on GPU implantation.

Making a system state follow a prescribed trajectory despite fluctuations and errors commonly consists of monitoring an observable (temperature, blood-glucose level, etc.) and reacting on its controllers (heater power, insulin amount, etc.). In the quantum domain, there is a change of paradigm in feedback, since measurements modify the state of the system, most dramatically when the trajectory goes through superpositions of measurement eigenstates. Here, we demonstrate the stabilization of an arbitrary trajectory of a superconducting qubit by measurement-based feedback. The protocol benefits from the long coherence time (T2 > 10 s) of the 3D transmon qubit, the high efficiency (82%) of the phasepreserving Josephson amplifier, and fast electronics that ensure less than 500 ns total delay. At discrete time intervals, the state of the qubit is measured and corrected in case an error is detected. For Rabi oscillations, where the discrete measurements occur when the qubit is supposed to be in the measurement pointer states, we demonstrate an average fidelity of 85% to the targeted trajectory. For Ramsey oscillations, which do not go through pointer states, the average fidelity reaches 76%. Incidentally, we demonstrate a fast reset protocol that allows us to cool a 3D transmon qubit down to 0:6% in the excited state.

At LPA, we study, among other things, the physical properties of Semiconductor Nanostructures. Many of these properties are in the optical domain. Until 2002 we only used monochromator systems with Avalanche Photodiodes (APD) and a spectrometer. The Performance of this kind of detector system is no longer efficient and so we began the development of CCD camera. As soon as the first system was installed, we were able to observe physical effects in these Nanostructures, as predicted by theory.