Qubits, the carriers of quantum information, are prone to errors induced by undesired environmental interactions. These errors accumulate during a quantum computation and correcting them is thus a key requirement for a reliable use of quantum computers.
Similar to conventional computers, the quantum computer requires a functioning system to correct errors, ABA — Invest in Austria reports, noting that researchers at the University of Innsbruck in collaboration with colleagues from RWTH Aachen and the University of Bologna presented a method in the scientific journal Nature that allows quantum computers to keep operating even if they lose some qubits on the way.
The researchers had to develop two key techniques to protect their quantum computer from the loss of qubits. The first challenge was to detect the loss of a qubit in the first place: “Measuring the qubit directly was not an option as this would destroy the quantum information that is stored in it“, explains Philipp Schindler from the University of Innsbruck. “We managed to overcome this problem by developing a technique where we used an additional ion to probe whether the qubit in question was still there or not, without disturbing it“, explains Martin Ringbauer.
The second challenge was to adapt the rest of the computation in real time in case the qubit was indeed lost. This adaptation is crucial to unscramble the quantum information after a loss and maintain protection of the remaining qubits. Thomas Monz, who leads the Innsbruck team, emphasizes that “all the building blocks developed in this work are readily applicable to other quantum computer architectures and other leading quantum error correction protocols.”