+---------------+
|   End User    |
+---------------+
      ^
      | Local Secure Interface
      | (e.g., the same physical hardware
      |  or a local secure network)    
      V                
+-----------------+     /--------\     +-----------------+         
|                 |--->( Quantum  )--->|                 |
|                 |    ( Internet )    |                 |
|     Quantum     |     \--------/     |    Quantum      |
|     Node A      |                    |     Node B      |
|                 |     /--------\     |                 |
|                 |    ( Classical)    |                 |
|                 |<-->( Internet )<-->|                 |
+-----------------+     \--------/     +-----------------+