Text this: Quantum memory process with a four-level atomic ensemble

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