In the long run the problem could also be solved by quantum repeating stations. Unfortunately they would require much more sophisticated quantum computation than the raw cryptography does. They will come along eventually, perhaps in a decade or two.

Another thing that will come along — probably after more than a decade or two — is quantum cryptanalysis, where you would use a quantum computer to decrypt existing codes. Quantum decryption machines would render existing cryptographic systems obsolete.

EDGE: Ten years from now will I have any quantum-computer technology on my desk?

DEUTSCH: I guess not. But who knows? I've been surprised repeatedly by how well the experimentalists have been able to implement theoretical concepts in quantum computing. But apart from quantum cryptography I'd be amazed if anything technologically useful comes out in ten years, 20 years, even longer. But I've been amazed before.