This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers from Jülich, Aachen and Cologne have performed a quantum operation on a qubit in just 6.8 nanoseconds—with more than 99.98% accuracy. Such operations typically take several tens of nanoseconds in superconducting quantum computers.
The paper was published in Nature Communications. 6.8 nanoseconds—that's how long it takes light to travel a distance of around two meters (6.6 feet) in a vacuum. In this tiny fraction of a second, researchers at the Peter Grünberg Institute for Functional Quantum Systems (PGI-13) and Quantum Control (PGI-8) at Forschungszentrum Jülich have succeeded in performing elementary computing operations on a quantum bit, or qubit for short. Switching speed is a critical factor in quantum computing.
This is because qubits are sensitive and retain their quantum states for only a limited time. The faster individual operations can be performed, the more can fit into this time window. This is important for complex algorithms and for resource-intensive error correction.
However, the shorter the microwave pulses used to switch qubits, the stronger they must be. This increases the risk of unwanted excitation. This is because superconducting qubits possess more than the two energy states used for computation.
If they are excited too strongly, they can unintentionally transition to higher energy levels. To put it simply, you can think of it like an elevator in a tall building, meant to carry its load only between the ground floor and the first floor. Raise the load too briskly and it can overshoot.
The team found that strong, rapid microwave pulses can not only push information one floor beyond its intended destination but also set it two or three floors higher through so-called multiphoton transitions—an effect that had previously been overlooked. Such multiphoton transitions in qubits are particularly treacherous: They can persist across multiple computational steps and impair quantum error correction. In close collaboration between the experimental group of Yuan Gao and Professor Rami Barends (PGI-13) and the theoretical group of José da Costa Jesus, Dr.
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