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Quantum technologies, such as quantum computers, quantum sensing devices and quantum memory, have often been found to outperform traditional electronics in speed and performance, and could thus soon help humans to tackle a variety of problems more efficiently. Despite their huge potential, most quantum systems are inherently susceptible to errors and noise, which poses a serious challenge to implementing and using them in real-world settings.

To enable the large-scale implementation of quantum technologies, researchers have been trying to develop techniques that could make them more resilient to noise and less prone to errors. While some of these methods, such as quantum error correction and fault tolerance, have proved to be useful and are now cornerstones of quantum information science, the factors that limit the performance of quantum systems in real-world applications are still poorly understood.

Researchers at University of Cambridge in the U.K. and Perimeter Institute for Theoretical Physics in Canada have recently tried to gain a theoretical understanding of the limitations of techniques for "purifying" noisy quantum resources. In a paper published in Physical Review Letters, they mathematically proved the existence of a series of universal limits on the accuracy and efficiency of methods to purify different types of quantum resources associated with practical applications, which play a key role in the functioning of quantum technologies.

"The ideas and techniques discussed in our paper originate from the general 'one-shot quantum resource theory,' which we outlined in one of our earlier PRL papers," Zi-Wen Liu, one of the researchers who carried out the study, told Phys.org. "The key idea is to analyze an information-theoretic quantity called the quantum hypothesis testing relative entropy, which is shown to induce universal limitations on noisy-state to pure-state transformations."