Quantum key distribution (QKD) 1,2 provides the only intrinsically unconditional secure method for communication based on principle of quantum mechanics. Compared with fiber-based demonstrations 3-5 , free-space links could provide the most appealing solution for much larger distance. Despite of significant efforts 6-13 , so far all realizations rely on stationary sites. Justifications are therefore extremely crucial for applications via a typical Low Earth Orbit Satellite (LEOS). To achieve direct and full-scale verifications, we demonstrate here three independent experiments with a decoy-state QKD system overcoming all the demanding conditions. The system is operated in a moving platform through a turntable, a floating platform through a hot-air balloon, and a huge loss channel, respectively, for substantiating performances under rapid motion, attitude change, vibration, random movement of satellites and in high-loss regime. The experiments cover expanded ranges for all the leading parameters of LEOS. Our results pave the way towards ground-satellite QKD and global quantum communication network.

properties, low cost, facile preparation and high defect tolerance. [1] Remarkable progress has been made, especially in terms of widespread applications spanning from solar cells, photodetectors, photocatalysts, and solid-state lasers to light-emitting diodes (LEDs). [2] In more recent years, owing to the exceptional luminescence properties, such as high brightness, color tunability, and intense absorption coefficient, lead halide perovskites have found promising potential applications as color converter for next-generation solid-state lightings and backlight displays. [3] Unfortunately, the intrinsic nature of poor stability and toxicity of lead halide perovskites are some serious issues to be tackled if the materials are to be used on a large scale. The chemical instability will severely restrict the lifespan of devices, and the accumulation of lead will cause serious environmental problems and fatal threat to human health. [4] Extensive efforts have been devoted to overcome the thorny challenges on the way to practical applications. To completely eliminate the potential danger of lead leakage, the simplest and practicable way is to replace it in the B site of ABX 3 with nontoxic isovalent metal ions. [5] As reasonable candidates, Ge 2+ and Sn 2+ ions are the first to come to mind for the substitution of Pb 2+ due to the same electronic configuration of ns 2 np 0 Lead halide perovskites have emerged as superstar semiconductors owing to their superior optoelectronic properties. However, the issues of chemical and thermodynamic instability and toxicity are yet to be resolved. Here, the non-and Bi 3+-doped all-inorganic lead-free perovskite derivatives are reported. Most remarkable is the successful extending of excitation of Cs 2 ZrCl 6 to match with the commercial near ultraviolet light-emitting diode chips via deliberate Bi 3+ aliovalent doping. The blue emission, contrary to self-trapped exciton (STE) emissions amply reported previously, originates from Bi 3+ ionoluminescence with a high photoluminescence quantum efficiency of 50%. The competition for harvesting electrons between STEs and Bi 3+ is studied in detail by steady-and transient-state fluorescence spectroscopy in combination with theoretical calculations. Surface grafting endows Cs 2 ZrCl 6 :Bi 3+ with a robust water-resistant core-shell-like structure and abiding emission. Surprisingly, the emission intensity even increases to 115.94% of the initial level after immersing in water for 2 h. The as-obtained phosphor enables the fabrication of a white light-emitting diode (w-LED), achieving CCT = 4179 K and Ra = 81.9. This work not only promotes the step toward development of leadfree, stable, and high-efficiency perovskite derivatives for the next-generation warm w-LEDs, but also reveals the structure-PL relationship.

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Persistent‐luminescence phosphors (PLPs) have a wide variety of applications in the fields of photonics and biophotonics due to their ultralong afterglow lifetime. However, the existing PLPs are charged and recharged with short‐wavelength high‐energy photons or inconvenient and potentially risky X‐ray beams. To date, deep tissue penetrable NIR light has mainly been used for photostimulated afterglow emission, which continues to decay and weaken after each cycle, Herein, a new paradigm of trap energy upconversion‐like near‐infrared (NIR) to near‐infrared light rejuvenateable persistent luminescence in bismuth‐doped calcium stannate phosphors and nanoparticles is reported. In contrast to the existing PLPs and persistent‐luminescence nanoparticles, the materials enable the occurrence of a reversed transition of the carriers from a deep‐level energy trap to a shallow‐level trap upon excitation by low‐energy NIR photons. Thus these new materials can be charged circularly via deep‐tissue penetrable NIR photons, which is unable to be done for existing PLPs, and emit afterglow signals. This conceptual work will lay the foundation to design new categories of NIR‐absorptive–NIR‐emissive PLPs and nanoparticles featuring physically harmless and deep tissue penetrable NIR light renewability and sets the stage for numerous biological applications, which have been limited by current materials.

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