Ciphers, quanta and computers

In early 1935, Albert Einstein, together with Boris Podolsky and Nathan Rosen, published a classic paper which questioned the completeness of quantum mechanical description of reality and, in a tacit way, introduced quantum entanglement. After playing a significant role in the development of the foundations of quantum mechanics, entanglement has been recently rediscovered as a new physical resource with potential commercial applications. In particular it can be used to construct new methods of secure communication and new methods of breaking ciphers. I will outline the evolution of the concept from its origin till today and describe some of its current applications in quantum cryptography and quantum computation.