Before quantum computers become as commonplace as PCs, it's plausible that advanced computing services could be rented out on remote quantum servers. The only problem is that sensitive data can be intercepted in transit or read by the owner of the server, compromising security. In 2009, scientists theorized in an IEEE paper that the problem could be solved without having any quantum capabilities on the client side, giving classical computer systems access to quantum computing power. Now those scientists have collaborated with researchers at the University of Vienna on an experiment that puts that theory into practice.
The system works by having the client encode data in quantum bits (qubits), which can't be read without changing them and being detected by the sender. No other quantum resources are required of the client. The qubits are then sent to the quantum server along with instructions for processing the information. After computation, the results are sent back to the client to be interpreted. Even if the server or some third party was able to read the information, it would make no sense because they are blind to the initial state of the qubits. In essence, the data is encrypted, processed, and returned without ever being decrypted.