Macquarie University researchers have fully mapped how noise spreads through quantum computers over time to show that glitches link together across different moments, creating a form of ‘memory’ that undermines calculations.
A team of Australian and international scientists has, for the first time, created a full picture of how errors unfold over time inside a quantum computer — a breakthrough that could help make future quantum machines far more reliable.
The researchers, led by Macquarie University’s Dr Christina Giarmatzi, found that the tiny errors that plague quantum computers don’t just appear randomly. Instead, they can linger, evolve and even link together across different moments in time.
The breakthrough opens the door to more advanced ways of modelling, predicting and correcting errors in quantum devices, not just in superconducting chips but also in systems such as trapped ions and spin qubits.
Previous attempts to map the behaviour of quantum systems over time all hit the same roadblock: after measuring a quantum system mid-experiment, scientists couldn’t freely set it up again for the next step, because the setting-up depends on whether the result of the measurement was 0 or 1.
The new method solves this by adding a clever twist, assuming that 50 per cent of the time, the result was 1, and the remaining time, the result was 0. Then, the researchers used software to work backwards with the data, to figure out what state it was in.
The team has made its experimental data and code openly available, and the full study is published in Quantum.