25 Jan
                
                    2021
                
            
            
                25 Jan
                
                '21
                
            
            
            
        
    
                11:53 p.m.
            
        Phys.org: Long-distance and secure quantum key distribution (QKD) over a free-space channel. https://phys.org/news/2021-01-long-distance-quantum-key-qkd-free-space.html