Text this

Number:

Provider:

CAPTCHA:

           _    _               _____    _    _   
    ___   | || | ||   ____     |  ___|| | \  / || 
   /   || | || | ||  |    \\   | ||__   |  \/  || 
  | [] || | \\_/ ||  | [] ||   | ||__   | .  . || 
   \__ ||  \____//   |  __//   |_____|| |_|\/|_|| 
    -|_||   `---`    |_|`-`    `-----`  `-`  `-`  
     `-`             `-`

Please enter what you see:

Text this: Non-Hermitian topological systems with eigenvalues that are always real