Since the introduction of the original ideas by Wiener and further development by Bennet, Brassard, Salvail, Smolin and others in the 1980’s, Quantum Cryptography has being making steady progress towards practical applications.
Currently some banks and government departments are using Quantum technology based on the transmission of single photons over fiber-optic links to transmit unconditionally secure cryptographic keys. However current technology allows for transmission only over relatively short distances at limited transmission rates.
One of the main drawbacks of quantum encryption is the difficulty of generating and transmitting individual photons without a loss of information because of interactions between photons and the medium.
An article describing Quantum Key Distribution can be found here.
I have compiled a list of companies (not exhaustive) that offer hardware based on different aspects of quantum cryptography. Without any claim of performance and in no particular order they are:
IBM, Hewlett-Packard and NEC also have extensive research projects on quantum cryptography. (NEC have announced delays in the marketing of its products).
There is a tremendous amount of research effort and money being spent on this technology as the prize for a practical technology that allows unconditional secure key generation will be huge.