Researchers from the Institute for Quantum Computing (IQC) and the Department of Applied Mathematics at the University of Waterloo have developed a universal method to manipulate quantum systems while minimizing their exposure to noise. Unlike related control methods that are designed for a particular physical setting, this new method is universal and can be applied regardless of the type of experimental set-up.
Performing a quantum computation or simulation involves quantum control – the ability to steer or manipulate a quantum system in a desired manner. Often, however, the process of controlling a quantum system exposes it to noise from its external environment, causing it to lose its quantum nature. The team of researchers found a novel method to steer a system while protecting it from noise, by steering it indirectly through an auxiliary quantum system called an actuator.
“We steer a system S, but instead of acting on it directly – for example, by addressing it with a laser – we act on an auxiliary system A, the actuator, which is coupled to S,” explained David Layden, a Master’s student in Applied Mathematics (Quantum Information). S is affected through its coupling with A, yet still remains protected from outside noise and therefore maintains its quantum behaviour. “The system S is steered indirectly. It’s as though we give it frequent gentle nudges with the actuator,” said Layden.
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