(EurekaAlert) Real-life applications like magnetometry or quantum gyroscope typically involve precise measurement on multiple parameters. How to achieve the ultimate precision limits simultaneously is a long sought-after grail in the field.
It is widely believed that the ultimate precision limits for all parameters cannot be achieved simultaneously, since generators of different parameters are generally non-commuting, which induces the trade-offs among the precisions.
Yet such trade-offs are escaped from by the group of Prof. LI Chuanfeng and Prof. XIANG Guoyong from Key Laboratory of Quantum Information at University of Science and Technology of China of the Chinese Academy of Sciences and their collaborator Prof. YUAN Haidong from Chinese University of Hongkong.
They counteracted the trade-offs and achieved the precision limit for the estimation of all three parameters in SU(2) operators simultaneously with 13.27 dB improvement over the shot-noise limit, which has been published in journal Science Advances.

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