Quantum computing gets closer with European QAP project

QAP (Qubit Applications integrated project) involves 35 European scientific and companies – and the organisation says that unbreakable cryptography, hitherto impossible simulations for complex problems and super-fast networks are just some of the promised outputs. "We are not looking to create a quantum computer directly," explains Professor Ian Walmsley, QAP co-coordinator. "Other people are working on that, and it will take a long time. We are, however, looking at some of the problems facing real-world quantum applications that we could deploy now." He refers, for example to storage of information encoded on a photon. "By focusing on these problems, we can perhaps create important new products that could be developed in the short and medium term." Chief among them is quantum cryptography. "Quantum computing, when it arrives, could make all current cryptographic technology obsolete. Quantum cryptography over short distances was demonstrated in a previous project. The problem is, it only works over a short distance," says Walmsley. Quantum cryptography relies on entanglement, he explains – a concept where two or more particles can exhibit correlation that would be impossible to explain unless they belonged to the same entity. Called quantum key distribution (QKD), the beauty is that it is immune to eavesdropping because the very act of observing an object changes the object observed. This encryption would be guaranteed by the laws of physics. Maintaining entanglement over long distances – so essential to QKD, but also communications and networks – is the most immediate and compelling QAP application, but there are others. QAP's work to develop quantum networks is progressing well, says Walmsley. One team has already developed a reliable way to calibrate and test detectors, for example. "This is important because it will be essential to develop reliable methods to test results if work on quantum networks is to progress," comments Walmsley.