May 8, 2015
      
                  
        
  Author(s)
  Yue Y. Zhao,   Jonathan E. Wyrick,   Donat F. Natterer,   Joaquin R. Nieva,   Cyprian  Lewandowski,   Kenji  Watanabe,    Takashi  Taniguchi,   Leonid  Levitov,   Nikolai B. Zhitenev,   Joseph A. Stroscio
 
       
            
    
    
        Designing high-finesse resonant cavities for electronic waves is hampered by the short coherence lengths in solids. Previous approaches, e.g. the seminal nanometer-sized quantum corrals, depend on careful positioning of adatoms at clean surfaces. Here we