The Nobel Prize in Physics 2005


The Nobel Prize in Physics 2005
  crypto   Guaranteed secure cryptography

One practical application of quantum optics is the possibility to exchange cryptographic keys without fear of their being broken – which is the bottleneck of all cryptography. These keys are used to encipher a message between a transmitter and a receiver. A cipher can be made unbreakable if the key is random and equally long as the message, the so-called Vernam cipher.


Quantum cryptography makes it possible to exchange keys entirely securely by transmitting faint light – single photons. Their security is guaranteed because, if anyone should try to eavesdrop the transmission by measuring the light, it will be affected and altered in accordance with the laws of quantum optics. This can be checked afterwards, so the transmitter and the receiver can easily see whether the key they have exchanged can be relied on.

To cite this section
MLA style: The Nobel Prize in Physics 2005. Nobel Media AB 2019. Mon. 18 Feb 2019. <>

Back to top Back To Top Takes users back to the top of the page

Explore prizes and laureates

Look for popular awards and laureates in different fields, and discover the history of the Nobel Prize.