As numerous companies continue their push to get us to entrust our data to the cloud, there are many still justifiably concerned about the security of cloud computing-based services. Now an international team of scientists have demonstrated that perfectly secure cloud computing is possible by combining the power of quantum computing with the security of quantum cryptography. They carried out what they claim is the first demonstration of "blind quantum computing," in which a quantum computation was carried out with the input, computation, and output all remaining unknown to the computer, and therefore, also any eavesdroppers.

While it is expected that quantum computers will play an important role in future information processing, some believe that - like today's supercomputers - they will be limited to a few specialized facilities around the world. While this brings to mind the quote most often attributed to IBM chairman Thomas Watson in 1943, "I think there is a world market for maybe five computers," given the inherent difficulties in building quantum devices, there's every chance such a scenario will eventuate - at least in the near term.

The international research team working at the Vienna Center for Quantum Science and Technology (VCQ) at the University of Vienna and the Institute for Quantum Optics and Quantum Information (IQOQI) says that quantum physics will enable remote users of such facilities to send and receive private data, safe in the knowledge that it is protected from prying eyes.

The researchers describe the process like this: "The user prepares qubits - the fundamental units of quantum computers - in a state known only to himself and sends these qubits to the quantum computer. The quantum computer entangles the qubits according to a standard scheme.

"The actual computation is measurement-based: the processing of quantum information is implemented by simple measurements on qubits. The user tailors measurement instructions to the particular state of each qubit and sends them to the quantum server.

"Finally, the results of the computation are sent back to the user who can interpret and utilize the results of the computation. Even if the quantum computer or an eavesdropper tries to read the qubits, they gain no useful information, without knowing the initial state; they are 'blind.'"

The researchers made what they believe is the first experimental demonstration of this blind quantum computing process by encoding the data using photons. These are well suited to the task as quantum computation operations can be carried out on them and they can be transmitted quickly over long distances.

"Quantum physics solves one of the key challenges in distributed computing. It can preserve data privacy when users interact with remote computing centers," says Stefanie Barz, lead author of the study, which appears in the journal Science.