Timing is everything, also for quantum computers

Timing is everything, also for quantum computers

Technology News |
By Wisse Hettinga

New research from a consortium of quantum physicists shows that imperfect timekeeping places a fundamental limit to quantum computers and their applications

The team, led by Trinity College Dublin’s Dr. Mark Mitchison, claims that even tiny timing errors add up to place a significant impact on any large-scale algorithm, posing another problem that must eventually be solved if quantum computers are to fulfill the lofty aspirations that society has for them.

The paper is published in the journal Physical Review Letters.

It is difficult to imagine modern life without clocks to help organize our daily schedules; with a digital clock in every person’s smartphone or watch, we take precise timekeeping for granted—although that doesn’t stop people from being late.

And for quantum computers, precise timing is even more essential, as they exploit the bizarre behavior of tiny particles—such as atoms, electrons, and photons—to process information.

“Mathematically speaking, changing a quantum state in a quantum computer corresponds to a rotation in an abstract high-dimensional space,” says Jake Xuereb from the Atomic Institute at the Vienna University of Technology, the first author of the paper. “In order to achieve the desired state in the end, the rotation must be applied for a very specific period of time—otherwise you turn the state either too little or too far.”

Given that real clocks are never perfect, the team investigated the impact of imperfect timing on quantum algorithms.

“A quantum algorithm is like an app that runs on a quantum computer,” explains Trinity’s Dr. Mitchison. “It was already known that timing errors could disrupt individual quantum logic gates, which are the building blocks of quantum algorithms. Our work extends this to full quantum algorithms, showing exactly how precise the clock must be to achieve a given computational accuracy.”

Learn more about the research on Quantum Timing at


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