Researchers lay foundations for larger quantum computers

Quantum information technologies use quantum bits – or qubits – as the elementary unit of information. More complex than classical bits, these qubits aid the construction of extremely powerful computers that can perform calculations faster than traditional computers.

Data is shuttled back and forth constantly within computers via different processors. However, quantum states are very sensitive and cannot be transmitted easily. Now, researchers at the Federal Institute of Technology in Zurich (ETH) have succeeded in transmitting quantum information between two qubits roughly a metre apart. To complete the transfer, the physicists used a coaxial cable.

“The important point of our method is that the transmission of the quantum state is deterministic, which means that it works at the push of a button,” explained Philipp Kurpiers, a PhD student at the ETH, in a statement.

In some earlier experiments, he added, a transfer of quantum states could already be realized, but that transmission was probabilistic: sometimes it worked and sometimes it didn’t.

“Our transmission rate for quantum states is among the highest ever realized, and at 80% our transmission fidelity is very good in the first realization of the protocol,” commented ETH professor Andreas Wallraff.

The researchers now want to develop the technology further, with the aim of trying to use two qubits each as transmitter and receiver – a process useful for larger computers. In future, quantum computers will consist of a more qubits than in current models. With a few hundred qubits, there is the issue of how to connect them most effectively in order to exploit the advantages of a quantum computer in the best possible way.