Last year, two quantum cryptographic systems were shown to be vulnerable to hacks which neither system registered. For years, quantum cryptographers have promised completely secure systems. However a year ago, a group led by Hoi-Kwong Lo at the University of Toronto in Ontario, Canada showed a vulnerability in quantum systems. It was a complete hack, but it still left some noticeable errors after the fact. Another hack led by Vadim Makarov at the Norwegian University of Science and Technology in Trondheim rendered a system incapable of recognizing a breach in security. With this second hack, the security of quantum systems became truly questionable. More recently, the team of this second project have introduced another method to exploit vulnerabilities in quantum systems.
To some extent, the research weakens the perception of security which quantum cryptography has always promised. However, the increasingly successful field of quantum hacking should not reduce confidence in the security of quantum systems. There are always vulnerabilities in any system, but quantum systems are still a viable choice for state of the art security. This research actually helps strengthen the security of such systems by exposing existing vulnerabilities. Once the vulnerabilities are out in the open, they can be dealt with accordingly.