We report on the on-ground stray light calibration of the hyperspectral Environmental Mapping and Analysis Program (EnMAP) satellite mission, which was successfully launched into space on April 1, 2022. EnMAP's optical payload consists of a visible and near-infrared (VNIR) (420-1000 nm) and a short wavelength infrared (SWIR) (900-2450 nm) imaging spectrometer. Using a custom-built light source and a collimator, we determined the diffuse stray light by measuring the point spread functions (PSFs) at 12 spatial and 15 (11 VNIR, 4 SWIR) spectral positions with a dynamic range between eight and nine orders of magnitude. Additionally, we measured the out-of-field stray light in along-track direction over an angular range of +/- 0.2 degrees, resulting in an along-track response function (AltRF) for each spectrometer unit with a dynamic range of similar to 10(7) . To reduce memory usage and computational time, we use a binned stray light extraction matrix to correct the diffuse stray light. The along-track out-of-field stray light of individual frames is corrected by subtracting preceding and following frames that are weighted with the AltRF. Finally, we show with simulations the impact of both types of stray light on a test scene and evaluate the performance of the presented correction methods in the same manner.

Imaging spectroscopy has been a recognized and established remote sensing technology since the 1980s, mainly using airborne and field-based platforms to identify and quantify key bio- and geo-chemical surface and atmospheric compounds, based on characteristic spectral reflectance features in the visible-near infrared (VNIR) and short-wave infrared (SWIR). Spaceborne missions, a leap in technology, were sparse, starting with the CHRIS/PROBA and EO1/Hyperion missions in the early 2000s, and providing spectroscopy data with limited spectral coverage and/or low data quality in the SWIR. Since 2019, several countries and agencies have successfully launched a number of spaceborne imaging spectroscopy systems into orbit or deployed them on the International Space Station (ISS) such as DESIS, PRISMA, HISUI, GF-5, EnMAP and EMIT. Among these recent missions, the German Environmental Mapping and Analysis Program (EnMAP) stands for its long-term development, sophisticated design with on-board calibration, high data quality requirements, and extensive accompanying science program. EnMAP was launched in April 2022 and, following a successful commissioning phase, started its operational activities in November 2022. The EnMAP mission encompasses global coverage from 80 degrees N to 80 degrees S through on-demand data acquisitions. Data are free and open access with 30 m spatial resolution, a high spectral resolution with a spectral sampling distance of 6.5 nm and 10 nm in the VNIR and SWIR regions respectively, and a high signal-to-noise ratio. In this paper, we aim to present the mission's current status, coverage, science capabilities and performance two years after launch. We show the potential of EnMAP for space-based imaging spectroscopy to operate in various environments, including high and low light levels, dense forests, Antarctic glaciers, and arid agricultural areas. EnMAP enables various applications in fields such as agriculture and forestry, soil compositional, raw materials, and methane mapping, as well as water quality assessment, and snow and ice properties. The results show that EnMAP's performance exceeds the mission requirements, and highlights the significant potential for contribution to scientific exploitation in various geo- and biochemical sciences. EnMAP is also expected to serve as a key tool for the development and testing of data processing algorithms for upcoming global operational missions.

We present the measurement results of the pre-flight characterization and calibration of the EnMAP HyperSpectral Imager (HSI) and draw conclusions on the performance of the instrument itself as well as the optical ground support equipment (OGSE) deployed.The HSI is capable of measuring the solar irradiance reflected from the Earth's surface as a continuous spectrum in the spectral range of 420 nm to 2450 nm, with an average spectral sampling of 6.5nm (VNIR) and 10nm (SWIR).The EnMAP swath of 30 km is sampled with 30 m in along and across track direction.The on-ground characterization was performed in air comprising a spectral, geometric, radiometric, polarimetric, and stray light characterization.For spectral calibration, a monochromator setup was used to characterize the spectral response function of the instrument yielding a wavelength and spectral resolution calibration including spectral smile.Geometric calibration was performed using a knife edge in the focal plane of a collimator allowing to determine the line of sight of each pixel.Additionally, the keystone and MTF performance of the instrument was confirmed.A large integrating sphere was used for radiometric characterization of the instrument.This provides an on-ground baseline calibration of radiometric coefficients and response non-uniformity to be updated in orbit.Additionally, the noise performance of the instrument was validated.A polarizer was used to measure polarization sensitivity of the instrument which was found to be in excellent agreement with expectations.Finally a stray light characterization of the instrument was conducted.

EnMAP (Environmental Mapping and Analysis Program) is a high-resolution imaging spectroscopy remote sensing mission that was successfully launched on April 1st, 2022. Equipped with a prism-based dual-spectrometer, EnMAP performs observations in the spectral range between 418.2nm and 2445.5nm with 224 bands and a high radiometric and spectral accuracy and stability. EnMAP products, with a ground instantaneous field-of-view of 30m×30m at a swath width of 30km, allow for the qualitative and quantitative analysis of surface variables from frequently and consistently acquired observations on a global scale. This article presents the EnMAP mission and details the activities and results of the Launch and Early Orbit and Commissioning Phases until November 1st, 2022. The mission capabilities and expected performances for the operational Routine Phase are provided for existing and future EnMAP users.

The Environmental Mapping and Analysis Program (EnMAP) is a German space borne science mission that aims to characterize the Earth’s environment on a global scale. The single payload of the satellite is the Hyperspectral Imager (HSI). It is capable of measuring the solar irradiance reflected from the Earth’s surface as a continuous spectrum in the spectral range of 420nm to 2450nm, with an average spectral sampling of 6.5nm (VNIR) and 10nm (SWIR). The EnMAP swath of 30km is sampled with 30m in along and across track direction. In these proceedings, we first give a brief overview the instrument design. We then explain the calibration strategy, which is a combination of on-ground and in-flight calibration measures. The on-ground calibration is presented in more detail. It aims to create a complete baseline calibration of the EnMAP instrument comprising a radiometric, spectral, geometric, polarimetric and straylight characterization. In orbit, a diffuser is used for absolute radiometric calibration via sun viewing. On-board calibration light sources ensure radiometric stability in between sun-viewings and spectral stability over the mission lifetime. Finally, we share first characterization data which are prototypical of the final instrument calibration.

An all-optical transistor is a device in which a gate light pulse switches the transmission of a target light pulse with a gain above unity. The gain quantifies the change of the transmitted target photon number per incoming gate photon. We study the quantum limit of one incoming gate photon and observe a gain of 20. The gate pulse is stored as a Rydberg excitation in an ultracold gas. The transmission of the subsequent target pulse is suppressed by Rydberg blockade which is enhanced by a Förster resonance. The detected target photons reveal in a single shot with a fidelity above 0.86 whether a Rydberg excitation was created during the gate pulse. The gain offers the possibility to distribute the transistor output to the inputs of many transistors, thus making complex computational tasks possible.

A computer based entirely on optical components could perform some tasks much faster than existing computers, which rely on electronic components whose speed is limited by heat generation. However, a fundamental limitation to making the components for an all-optical processor is that photons do not interact: unlike electrons that interact strongly and therefore can easily be used to manipulate other electrons, interactions between photons are generally too weak for one or several photons to be able to block or redirect others. However, recent experiments have shown that highly excited atomic states could mediate the necessary coupling between photons [1–3]. Experimentalists have used these states to make a single-photon source [2], a single-photon phase shifter [3], and now, as reported by two independent research groups in Physical Review Letters, a single-photon transistor [4, 5]. Gerhard Rempe and his colleagues at the Max Planck Institute of Quantum Optics and Sebastian Hofferberth and his colleagues at University of Stuttgart, both in Germany, have succeeded in making the first single-photon transistors with high gain—a measure of efficiency—which is a key step to their being used to build more complex optical circuits.

AbstractDurchdringen sich zwei Lichtstrahlen, so beeinflussen diese sich gegenseitige normalerweise nicht. Dennoch ist es kürzlich sowohl unserer Gruppe am Max‐Planck‐Institut für Quantenoptik in Garching als auch einer Gruppe in Stuttgart gelungen, einen Lichtstrahl mit nur einem einzigen Photon zu schalten. Damit wurde das optische Analogon eines Transistors realisiert.

All-optical switching is a technique in which a gate light pulse changes the transmission of a target light pulse without the detour via electronic signal processing. We take this to the quantum regime, where the incoming gate light pulse contains only one photon on average. The gate pulse is stored as a Rydberg excitation in an ultracold atomic gas using electromagnetically induced transparency. Rydberg blockade suppresses the transmission of the subsequent target pulse. Finally, the stored gate photon can be retrieved. A retrieved photon heralds successful storage. The corresponding postselected subensemble shows an extinction of 0.05. The single-photon switch offers many interesting perspectives ranging from quantum communication to quantum information processing.

An all-optical transistor is a device in which a gate light pulse switches the transmission of a target light pulse with a gain above unity. The gain quantifies the change of the transmitted target photon number per incoming gate photon. We study the quantum limit of one incoming gate photon and observe a gain of 20. The gate pulse is stored as a Rydberg excitation in an ultracold gas. The transmission of the subsequent target pulse is suppressed by Rydberg blockade, which is enhanced by a Förster resonance. The detected target photons reveal in a single shot with a fidelity above 0.86 whether a Rydberg excitation was created during the gate pulse. The gain offers the possibility to distribute the transistor output to the inputs of many transistors, thus making complex computational tasks possible.

A classical logic gate connecting input and output light pulses is demonstrated. The gate operation is based on three steps: First, two incoming light pulses are stored in a Bose-Einstein condensate, second, atomic four-wave mixing generates a new matter wave, and third, the light pulses are retrieved. In the presence of the new matter wave, the retrieval generates a new optical wave. The latter will only be generated if both input light pulses are applied, thus realizing an AND gate. Finally, we show that the gate operation is phase coherent, an essential prerequisite for a quantum logic gate.

A scheme based on electromagnetically induced transparency is used to store light in a Bose-Einstein condensate. In this process, a photonic polarization qubit is stored in atomic Zeeman states. The performance of the storage process is characterized and optimized. The average process fidelity is 1.000 +/- 0.004. For long storage times, temporal fluctuations of the magnetic field reduce this value, yielding a lifetime of the fidelity of (1.1 +/- 0.2) ms. The write-read efficiency of the pulse energy can reach 0.53 +/- 0.05.